View Source Flop (Flop v0.17.0)

Flop is a helper library for filtering, ordering and pagination with Ecto.

usage

Usage

The simplest way of using this library is just to use Flop.validate_and_run/3 and Flop.validate_and_run!/3. Both functions take a queryable and a parameter map, validate the parameters, run the query and return the query results and the meta information.

iex> Flop.Repo.insert_all(Flop.Pet, [
...>   %{name: "Harry", age: 4, species: "C. lupus"},
...>   %{name: "Maggie", age: 1, species: "O. cuniculus"},
...>   %{name: "Patty", age: 2, species: "C. aegagrus"}
...> ])
iex> params = %{order_by: ["name", "age"], page: 1, page_size: 2}
iex> {:ok, {results, meta}} =
...>   Flop.validate_and_run(
...>     Flop.Pet,
...>     params,
...>     repo: Flop.Repo
...>   )
iex> Enum.map(results, & &1.name)
["Harry", "Maggie"]
iex> meta.total_count
3
iex> meta.total_pages
2
iex> meta.has_next_page?
true

Under the hood, these functions just call Flop.validate/2 and Flop.run/3, which in turn calls Flop.all/3 and Flop.meta/3. If you need finer control about if and when to execute each step, you can call those functions directly.

See Flop.Meta for descriptions of the meta fields.

global-configuration

Global configuration

You can set some global options like the default Ecto repo via the application environment. All global options can be overridden by passing them directly to the functions or configuring the options for a schema module via Flop.Schema.

import Config

config :flop, repo: MyApp.Repo

See Flop.option/0 for a description of all available options.

config-modules

Config modules

Instead of setting global options in the application environment, you can also create a Flop config module. This is especially useful in an umbrella application, or if you have multiple Repos.

defmodule MyApp.Flop do
  use Flop, repo: MyApp.Repo, default_limit: 25
end

This will define wrapper functions around all Flop functions that take a query, Flop parameters and options:

So instead of using Flop.validate_and_run/3, you would call MyApp.Flop.validate_and_run/3.

If you have both a config module and a global application config, Flop will fall back to the application config if an option is not set.

See Flop.option/0 for a description of all available options.

schema-options

Schema options

You can set some options for a schema by deriving Flop.Schema. The options are evaluated at the validation step.

defmodule Pet do
  use Ecto.Schema

  @derive {Flop.Schema,
           filterable: [:name, :species],
           sortable: [:name, :age],
           default_limit: 20,
           max_limit: 100}

  schema "pets" do
    field :name, :string
    field :age, :integer
    field :species, :string
    field :social_security_number, :string
  end
end

You need to pass the schema to Flop.validate/2 or any function that includes the validation step with the :for option.

iex> params = %{"order_by" => ["name", "age"], "limit" => 5}
iex> {:ok, flop} = Flop.validate(params, for: Flop.Pet)
iex> flop.limit
5

iex> params = %{"order_by" => ["name", "age"], "limit" => 10_000}
iex> {:error, meta} = Flop.validate(params, for: Flop.Pet)
iex> [limit: [{msg, _}]] = meta.errors
iex> msg
"must be less than or equal to %{number}"

iex> params = %{"order_by" => ["name", "age"], "limit" => 10_000}
iex> {:error, %Flop.Meta{} = meta} =
...>   Flop.validate_and_run(
...>     Flop.Pet,
...>     params,
...>     for: Flop.Pet
...>   )
iex> [limit: [{msg, _}]] = meta.errors
iex> msg
"must be less than or equal to %{number}"

ordering

Ordering

To add an ordering clause to a query, you need to set the :order_by and optionally the :order_directions parameter. :order_by should be the list of fields, while :order_directions is a list of Flop.order_direction/0. :order_by and :order_directions are zipped when generating the ORDER BY clause. If no order directions are given, :asc is used as default.

iex> params = %{
...>   "order_by" => ["name", "age"],
...>   "order_directions" => ["asc", "desc"]
...> }
iex> {:ok, flop} = Flop.validate(params)
iex> flop.order_by
[:name, :age]
iex> flop.order_directions
[:asc, :desc]

Flop uses these two fields instead of a keyword list, so that the order instructions can be easily passed in a query string.

pagination

Pagination

For queries using OFFSET and LIMIT, you have the choice between page-based pagination parameters:

%{page: 5, page_size: 20}

and offset-based pagination parameters:

%{offset: 100, limit: 20}

For cursor-based pagination, you can either use :first/:after or :last/:before. You also need to pass the :order_by parameter or set a default order for the schema via Flop.Schema.

iex> Flop.Repo.insert_all(Flop.Pet, [
...>   %{name: "Harry", age: 4, species: "C. lupus"},
...>   %{name: "Maggie", age: 1, species: "O. cuniculus"},
...>   %{name: "Patty", age: 2, species: "C. aegagrus"}
...> ])
iex>
iex> # forward (first/after)
iex>
iex> params = %{first: 2, order_by: [:species, :name]}
iex> {:ok, {results, meta}} = Flop.validate_and_run(Flop.Pet, params)
iex> Enum.map(results, & &1.name)
["Patty", "Harry"]
iex> meta.has_next_page?
true
iex> end_cursor = meta.end_cursor
"g3QAAAACZAAEbmFtZW0AAAAFSGFycnlkAAdzcGVjaWVzbQAAAAhDLiBsdXB1cw=="
iex> params = %{first: 2, after: end_cursor, order_by: [:species, :name]}
iex> {:ok, {results, meta}} = Flop.validate_and_run(Flop.Pet, params)
iex> Enum.map(results, & &1.name)
["Maggie"]
iex> meta.has_next_page?
false
iex>
iex> # backward (last/before)
iex>
iex> params = %{last: 2, order_by: [:species, :name]}
iex> {:ok, {results, meta}} = Flop.validate_and_run(Flop.Pet, params)
iex> Enum.map(results, & &1.name)
["Harry", "Maggie"]
iex> meta.has_previous_page?
true
iex> start_cursor = meta.start_cursor
"g3QAAAACZAAEbmFtZW0AAAAFSGFycnlkAAdzcGVjaWVzbQAAAAhDLiBsdXB1cw=="
iex> params = %{last: 2, before: start_cursor, order_by: [:species, :name]}
iex> {:ok, {results, meta}} = Flop.validate_and_run(Flop.Pet, params)
iex> Enum.map(results, & &1.name)
["Patty"]
iex> meta.has_previous_page?
false

By default, it is assumed that the query result is a list of maps or structs. If your query returns a different data structure, you can pass the :cursor_value_func option to retrieve the cursor values. See Flop.option/0 and Flop.Cursor for more information.

You can restrict which pagination types are available. See Flop.option/0 for details.

filters

Filters

Filters can be passed as a list of maps. It is recommended to define the filterable fields for a schema using Flop.Schema.

iex> Flop.Repo.insert_all(Flop.Pet, [
...>   %{name: "Harry", age: 4, species: "C. lupus"},
...>   %{name: "Maggie", age: 1, species: "O. cuniculus"},
...>   %{name: "Patty", age: 2, species: "C. aegagrus"}
...> ])
iex>
iex> params = %{filters: [%{field: :name, op: :=~, value: "Mag"}]}
iex> {:ok, {results, meta}} = Flop.validate_and_run(Flop.Pet, params)
iex> meta.total_count
1
iex> [pet] = results
iex> pet.name
"Maggie"

See Flop.Filter.op/0 for a list of all available filter operators.

graphql-and-relay

GraphQL and Relay

The parameters used for cursor-based pagination follow the Relay specification, so you can just pass the arguments you get from the client on to Flop.

Flop.Relay can convert the query results returned by Flop.validate_and_run/3 into Edges and PageInfo formats required for Relay connections.

For example, if you have a context module like this:

defmodule MyApp.Flora
  import Ecto.query, warn: false

  alias MyApp.Flora.Plant

  def list_plants_by_continent(%Continent{} = continent, %{} = args) do
    Plant
    |> where(continent_id: ^continent.id)
    |> Flop.validate_and_run(args, for: Plant)
  end
end

Then your Absinthe resolver for the plants connection may look something like this:

def list_plants(args, %{source: %Continent{} = continent}) do
  with {:ok, result} <-
         Flora.list_plants_by_continent(continent, args) do
    {:ok, Flop.Relay.connection_from_result(result)}
  end
end

Link to this section Summary

Types

Options that can be passed to most of the functions or that can be set via the application environment.

Represents the supported order direction values.

Represents the pagination type.

t()

Represents the query parameters for filtering, ordering and pagination.

Functions

Applies the given Flop to the given queryable and returns all matchings entries.

Returns the names of the bindings that are required for the filters and order clauses of the given Flop.

Returns the total count of entries matching the filter conditions of the Flop.

Returns the current order direction for the given field.

Applies the filter parameter of a Flop.t/0 to an Ecto.Queryable.t/0.

Returns the option with the given key.

Converts a map of filter conditions into a list of Flop filter params.

Returns meta information for the given query and flop that can be used for building the pagination links.

Converts key/value filter parameters at the root of a map, converts them into a list of filter parameter maps and nests them under the :filters key.

Applies the order_by and order_directions parameters of a Flop.t/0 to an Ecto.Queryable.t/0.

Applies the pagination parameters of a Flop.t/0 to an Ecto.Queryable.t/0.

Updates the order_by and order_directions values of a Flop struct.

Adds clauses for filtering, ordering and pagination to a Ecto.Queryable.t/0.

Removes the after and before cursors from a Flop struct.

Removes all filters from a Flop struct.

Removes the order parameters from a Flop struct.

Applies the given Flop to the given queryable, retrieves the data and the meta data.

Takes a Flop.Meta struct and returns a Flop struct with updated cursor pagination params for going to either the previous or the next page.

Sets the offset value of a Flop struct while also removing/converting pagination parameters for other pagination types.

Sets the page value of a Flop struct while also removing/converting pagination parameters for other pagination types.

Takes a Flop.Meta struct and returns a Flop struct with updated cursor pagination params for going to the next page.

Sets the offset of a Flop struct to the next page depending on the limit.

Sets the page of a Flop struct to the next page.

Takes a Flop.Meta struct and returns a Flop struct with updated cursor pagination params for going to the previous page.

Sets the offset of a Flop struct to the page depending on the limit.

Sets the page of a Flop struct to the previous page, but not less than 1.

Same as Flop.validate/2, but raises an Ecto.InvalidChangesetError if the parameters are invalid.

Validates the given flop parameters and retrieves the data and meta data on success.

Link to this section Types

@type option() ::
  {:cursor_value_func, (any(), [atom()] -> map())}
  | {:default_limit, pos_integer()}
  | {:default_order,
     %{
       :order_by => [atom()],
       optional(:order_directions) => [order_direction()]
     }}
  | {:default_pagination_type, pagination_type()}
  | {:filtering, boolean()}
  | {:for, module()}
  | {:max_limit, pos_integer()}
  | {:order_query, Ecto.Queryable.t()}
  | {:ordering, boolean()}
  | {:pagination, boolean()}
  | {:pagination_types, [pagination_type()]}
  | {:repo, module()}
  | {:query_opts, Keyword.t()}

Options that can be passed to most of the functions or that can be set via the application environment.

  • :cursor_value_func - 2-arity function used to get the (unencoded) cursor value from a record. Only used with cursor-based pagination. The first argument is the record, the second argument is the list of fields used in the ORDER BY clause. Needs to return a map with the order fields as keys and the the record values of these fields as values. Defaults to Flop.Cursor.get_cursor_from_node/2.
  • :default_limit - Sets a global default limit for queries that is used if no default limit is set for a schema and no limit is set in the parameters. Can only be set in the application configuration.
  • :default_order - Sets the default order for a query if none is passed in the parameters or if ordering is disabled. Can be set in the schema or in the options passed to the query functions.
  • :default_pagination_type - The pagination type to use when setting default parameters and the pagination type cannot be determined from the parameters. Parameters for other pagination types can still be passed when setting this option. To restrict which pagination types can be used, set the :pagination_types option.
  • :filtering (boolean) - Can be set to false to silently ignore filter parameters.
  • :for - The schema module to be used for validation. Flop.Schema must be derived for the given module. This option is optional and can not be set globally. If it is not set, schema specific validation will be omitted. Used by the validation functions. It is also used to determine which fields are join and compound fields.
  • :max_limit - Sets a global maximum limit for queries that is used if no maximum limit is set for a schema. Can only be set in the application configuration.
  • :order_query - Allows you to set a separate base query for counting. Can only be passed as an option to one of the query functions. See Flop.validate_and_run/3 and Flop.count/3.
  • :pagination (boolean) - Can be set to false to silently ignore pagination parameters.
  • :pagination_types - Defines which pagination types are allowed. Parameters for other pagination types will not be cast. By default, all pagination types are allowed. See also Flop.pagination_type/0.
  • :query_opts - These options are passed to the Ecto.Repo query functions. See the Ecto documentation for Ecto.Repo.all/2, Ecto.Repo.aggregate/3, and the "Shared Options" section of Ecto.Repo.
  • :ordering (boolean) - Can be set to false to silently ignore order parameters. Default orders are still applied.
  • :repo - The Ecto Repo module to use for the database query. Used by all functions that execute a database query.

All options can be passed directly to the functions. Some of the options can be set on a schema level via Flop.Schema.

All options except :for, :default_order and :count_query can be set globally via the application environment.

import Config

config :flop,
  default_limit: 25,
  filtering: false,
  cursor_value_func: &MyApp.Repo.get_cursor_value/2,
  max_limit: 100,
  ordering: false,
  pagination_types: [:first, :last, :page],
  repo: MyApp.Repo,
  query_opts: [prefix: "some-prefix"]

The look up order is:

  1. option passed to function
  2. option set for schema using Flop.Schema (only :max_limit, :default_limit, :default_order and :pagination_types)
  3. option set in config module, if one is used (except :for, :default_order and :count_query; see section "Config modules" in the module documentation)
  4. option set in global config (except :for, :default_order and :count_query)
  5. default value (only :cursor_value_func)
@type order_direction() ::
  :asc
  | :asc_nulls_first
  | :asc_nulls_last
  | :desc
  | :desc_nulls_first
  | :desc_nulls_last

Represents the supported order direction values.

@type pagination_type() :: :offset | :page | :first | :last

Represents the pagination type.

  • :offset - pagination using the offset and limit parameters
  • :page - pagination using the page and page_size parameters
  • :first - cursor-based pagination using the first and after parameters
  • :last - cursor-based pagination using the last and before parameters
@type t() :: %Flop{
  after: String.t() | nil,
  before: String.t() | nil,
  filters: [Flop.Filter.t()] | nil,
  first: pos_integer() | nil,
  last: pos_integer() | nil,
  limit: pos_integer() | nil,
  offset: non_neg_integer() | nil,
  order_by: [atom() | String.t()] | nil,
  order_directions: [order_direction()] | nil,
  page: pos_integer() | nil,
  page_size: pos_integer() | nil
}

Represents the query parameters for filtering, ordering and pagination.

fields

Fields

  • after: Used for cursor-based pagination. Must be used with first or a default limit.
  • before: Used for cursor-based pagination. Must be used with last or a default limit.
  • limit, offset: Used for offset-based pagination.
  • first Used for cursor-based pagination. Can be used alone to begin pagination or with after
  • last Used for cursor-based pagination.
  • page, page_size: Used for offset-based pagination as an alternative to offset and limit.
  • order_by: List of fields to order by. Fields can be restricted by deriving Flop.Schema in your Ecto schema.
  • order_directions: List of order directions applied to the fields defined in order_by. If empty or the list is shorter than the order_by list, :asc will be used as a default for each missing order direction.
  • filters: List of filters, see Flop.Filter.t/0.

Link to this section Functions

Link to this function

all(q, flop, opts \\ [])

View Source (since 0.6.0)
@spec all(Ecto.Queryable.t(), t(), [option()]) :: [any()]

Applies the given Flop to the given queryable and returns all matchings entries.

iex> Flop.all(Flop.Pet, %Flop{}, repo: Flop.Repo)
[]

You can also configure a default repo in your config files:

config :flop, repo: MyApp.Repo

This allows you to omit the third argument:

iex> Flop.all(Flop.Pet, %Flop{})
[]

Note that when using cursor-based pagination, the applied limit will be first + 1 or last + 1. The extra record is removed by Flop.run/3, but not by this function.

This function does not validate the given Flop struct. Be sure to validate any user-generated parameters with validate/2 or validate!/2 before passing them to this function.

Link to this function

bindings(flop, module, opts \\ [])

View Source (since 0.16.0)

Returns the names of the bindings that are required for the filters and order clauses of the given Flop.

The second argument is the schema module that derives Flop.Schema.

For example, your schema module might define a join field called :owner_age.

@derive {
  Flop.Schema,
  filterable: [:name, :owner_age],
  sortable: [:name, :owner_age],
  join_fields: [owner_age: {:owner, :age}]
}

If you pass a Flop with a filter on the :owner_age field, the returned list will include the :owner binding.

iex> bindings(
...>   %Flop{
...>     filters: [%Flop.Filter{field: :owner_age, op: :==, value: 5}]
...>   },
...>   Flop.Pet
...> )
[:owner]

If on the other hand only normal fields or compound fields are used in the filter and order options, an empty list will be returned.

iex> bindings(
...>   %Flop{
...>     filters: [%Flop.Filter{field: :name, op: :==, value: "George"}]
...>   },
...>   Flop.Pet
...> )
[]

You can use this to dynamically build the join clauses needed for the query.

def list_pets(params) do
  with {:ok, flop} <- Flop.validate(params, for: Pet) do
    bindings = Flop.bindings(flop, Pet)

    Pet
    |> join_pet_assocs(bindings)
    |> Flop.run(flop, for: Pet)
  end
end

defp join_pet_assocs(q, bindings) when is_list(bindings) do
  Enum.reduce(bindings, q, fn
    :owner, acc ->
      join(acc, :left, [p], o in assoc(p, :owner), as: :owner)

    :toys, acc ->
      join(acc, :left, [p], t in assoc(p, :toys), as: :toys)
  end)
end

For more information about join fields, refer to the module documentation of Flop.Schema.

options

Options

  • :order - If false, only bindings needed for filtering are included. Defaults to true.
Link to this function

count(q, flop, opts \\ [])

View Source (since 0.6.0)
@spec count(Ecto.Queryable.t(), t(), [option()]) :: non_neg_integer()

Returns the total count of entries matching the filter conditions of the Flop.

The pagination and ordering option are disregarded.

iex> Flop.count(Flop.Pet, %Flop{}, repo: Flop.Repo)
0

You can also configure a default repo in your config files:

config :flop, repo: MyApp.Repo

This allows you to omit the third argument:

iex> Flop.count(Flop.Pet, %Flop{})
0

You can override the default query by passing the :count_query option. This doesn't make a lot of sense when you use count/3 directly, but allows you to optimize the count query when you use one of the run/3, validate_and_run/3 and validate_and_run!/3 functions.

query = join(Pet, :left, [p], o in assoc(p, :owner))
count_query = Pet
count(query, %Flop{}, count_query: count_query)

The filter parameters of the given Flop are applied to the custom count query.

This function does not validate the given Flop struct. Be sure to validate any user-generated parameters with validate/2 or validate!/2 before passing them to this function.

Link to this function

current_order(flop, field)

View Source (since 0.15.0)
@spec current_order(t(), atom()) :: order_direction() | nil

Returns the current order direction for the given field.

examples

Examples

iex> flop = %Flop{order_by: [:name, :age], order_directions: [:desc]}
iex> current_order(flop, :name)
:desc
iex> current_order(flop, :age)
:asc
iex> current_order(flop, :species)
nil
Link to this function

filter(q, flop, opt \\ [])

View Source
@spec filter(Ecto.Queryable.t(), t(), [option()]) :: Ecto.Queryable.t()

Applies the filter parameter of a Flop.t/0 to an Ecto.Queryable.t/0.

Used by Flop.query/2.

This function does not validate the given Flop struct. Be sure to validate any user-generated parameters with validate/2 or validate!/2 before passing them to this function.

Link to this function

get_option(key, opts, default \\ nil)

View Source (since 0.11.0)
@spec get_option(atom(), [option()], any()) :: any()

Returns the option with the given key.

The look-up order is:

  1. the keyword list passed as the second argument
  2. the schema module that derives Flop.Schema, if the passed list includes the :for option
  3. the application environment
  4. the default passed as the last argument
Link to this function

map_to_filter_params(map, opts \\ [])

View Source (since 0.14.0)
@spec map_to_filter_params(
  map(),
  keyword()
) :: [map()]

Converts a map of filter conditions into a list of Flop filter params.

The default operator is :==. nil values are excluded from the result.

iex> map_to_filter_params(%{name: "George", age: 8, species: nil})
[
  %{field: :age, op: :==, value: 8},
  %{field: :name, op: :==, value: "George"}
]

iex> map_to_filter_params(%{"name" => "George", "age" => 8, "cat" => true})
[
  %{"field" => "age", "op" => :==, "value" => 8},
  %{"field" => "cat", "op" => :==, "value" => true},
  %{"field" => "name", "op" => :==, "value" => "George"}
]

You can optionally pass a mapping from field names to operators as a map with atom keys.

iex> map_to_filter_params(
...>   %{name: "George", age: 8, species: nil},
...>   operators: %{name: :ilike_and}
...> )
[
  %{field: :age, op: :==, value: 8},
  %{field: :name, op: :ilike_and, value: "George"}
]

iex> map_to_filter_params(
...>   %{"name" => "George", "age" => 8, "cat" => true},
...>   operators: %{name: :ilike_and, age: :<=}
...> )
[
  %{"field" => "age", "op" => :<=, "value" => 8},
  %{"field" => "cat", "op" => :==, "value" => true},
  %{"field" => "name", "op" => :ilike_and, "value" => "George"}
]
Link to this function

meta(query_or_results, flop, opts \\ [])

View Source (since 0.6.0)
@spec meta(Ecto.Queryable.t() | [any()], t(), [option()]) :: Flop.Meta.t()

Returns meta information for the given query and flop that can be used for building the pagination links.

iex> Flop.meta(Flop.Pet, %Flop{limit: 10}, repo: Flop.Repo)
%Flop.Meta{
  current_offset: 0,
  current_page: 1,
  end_cursor: nil,
  flop: %Flop{limit: 10},
  has_next_page?: false,
  has_previous_page?: false,
  next_offset: nil,
  next_page: nil,
  page_size: 10,
  previous_offset: nil,
  previous_page: nil,
  start_cursor: nil,
  total_count: 0,
  total_pages: 0
}

The function returns both the current offset and the current page, regardless of the pagination type. If the offset lies in between pages, the current page number is rounded up. This means that it is possible that the values for current_page and next_page can be identical. This can only occur if you use offset/limit based pagination with arbitrary offsets, but in that case, you will use the previous_offset, current_offset and next_offset values to render the pagination links anyway, so this shouldn't be a problem.

Unless cursor-based pagination is used, this function will run a query to figure get the total count of matching records.

This function does not validate the given Flop struct. Be sure to validate any user-generated parameters with validate/2 or validate!/2 before passing them to this function.

Link to this function

nest_filters(args, fields, opts \\ [])

View Source (since 0.15.0)

Converts key/value filter parameters at the root of a map, converts them into a list of filter parameter maps and nests them under the :filters key.

The second argument is a list of fields as atoms.

The opts argument is passed to map_to_filter_params/2.

examples

Examples

iex> nest_filters(%{name: "Peter", page_size: 10}, [:name])
%{filters: [%{field: :name, op: :==, value: "Peter"}], page_size: 10}

iex> nest_filters(%{"name" => "Peter"}, [:name])
%{"filters" => [%{"field" => "name", "op" => :==, "value" =>  "Peter"}]}

iex> nest_filters(%{name: "Peter"}, [:name], operators: %{name: :!=})
%{filters: [%{field: :name, op: :!=, value: "Peter"}]}
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order_by(q, flop, opts \\ [])

View Source
@spec order_by(Ecto.Queryable.t(), t(), [option()]) :: Ecto.Queryable.t()

Applies the order_by and order_directions parameters of a Flop.t/0 to an Ecto.Queryable.t/0.

Used by Flop.query/2.

This function does not validate the given Flop struct. Be sure to validate any user-generated parameters with validate/2 or validate!/2 before passing them to this function.

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paginate(q, flop, opts \\ [])

View Source
@spec paginate(Ecto.Queryable.t(), t(), [option()]) :: Ecto.Queryable.t()

Applies the pagination parameters of a Flop.t/0 to an Ecto.Queryable.t/0.

The function supports both offset/limit based pagination and page/page_size based pagination.

If you validated the Flop.t/0 with Flop.validate/1 before, you can be sure that the given Flop.t/0 only has pagination parameters set for one pagination method. If you pass an unvalidated Flop.t/0 that has pagination parameters set for multiple pagination methods, this function will arbitrarily only apply one of the pagination methods.

Used by Flop.query/2.

This function does not validate the given Flop struct. Be sure to validate any user-generated parameters with validate/2 or validate!/2 before passing them to this function.

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push_order(flop, field)

View Source (since 0.10.0)
@spec push_order(t(), atom() | String.t()) :: t()

Updates the order_by and order_directions values of a Flop struct.

  • If the field is not in the current order_by value, it will be prepended to the list. The order direction for the field will be set to :asc.
  • If the field is already at the front of the order_by list, the order direction will be reversed.
  • If the field is already in the list, but not at the front, it will be moved to the front and the order direction will be set to :asc.

example

Example

iex> flop = push_order(%Flop{}, :name)
iex> flop.order_by
[:name]
iex> flop.order_directions
[:asc]
iex> flop = push_order(flop, :age)
iex> flop.order_by
[:age, :name]
iex> flop.order_directions
[:asc, :asc]
iex> flop = push_order(flop, :age)
iex> flop.order_by
[:age, :name]
iex> flop.order_directions
[:desc, :asc]
iex> flop = push_order(flop, :species)
iex> flop.order_by
[:species, :age, :name]
iex> flop.order_directions
[:asc, :desc, :asc]
iex> flop = push_order(flop, :age)
iex> flop.order_by
[:age, :species, :name]
iex> flop.order_directions
[:asc, :asc, :asc]

If a string is passed as the second argument, it will be converted to an atom using String.to_existing_atom/1. If the atom does not exist, the Flop struct will be returned unchanged.

iex> flop = push_order(%Flop{}, "name")
iex> flop.order_by
[:name]
iex> flop = push_order(%Flop{}, "this_atom_does_not_exist")
iex> flop.order_by
nil

Since the pagination cursor depends on the sort order, the :before and :after parameters are reset.

iex> push_order(%Flop{order_by: [:id], after: "ABC"}, :name)
%Flop{order_by: [:name, :id], order_directions: [:asc], after: nil}
iex> push_order(%Flop{order_by: [:id], before: "DEF"}, :name)
%Flop{order_by: [:name, :id], order_directions: [:asc], before: nil}
Link to this function

query(q, flop, opts \\ [])

View Source
@spec query(Ecto.Queryable.t(), t(), [option()]) :: Ecto.Queryable.t()

Adds clauses for filtering, ordering and pagination to a Ecto.Queryable.t/0.

The parameters are represented by the Flop.t/0 type. Any nil values will be ignored.

This function does not validate the given Flop struct. Be sure to validate any user-generated parameters with validate/2 or validate!/2 before passing them to this function.

examples

Examples

iex> flop = %Flop{limit: 10, offset: 19}
iex> Flop.query(Flop.Pet, flop)
#Ecto.Query<from p0 in Flop.Pet, limit: ^10, offset: ^19>

Or enhance an already defined query:

iex> require Ecto.Query
iex> flop = %Flop{limit: 10}
iex> Flop.Pet |> Ecto.Query.where(species: "dog") |> Flop.query(flop)
#Ecto.Query<from p0 in Flop.Pet, where: p0.species == "dog", limit: ^10>

Note that when using cursor-based pagination, the applied limit will be first + 1 or last + 1. The extra record is removed by Flop.run/3.

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reset_cursors(flop)

View Source (since 0.15.0)
@spec reset_cursors(t()) :: t()

Removes the after and before cursors from a Flop struct.

example

Example

iex> reset_cursors(%Flop{after: "A"})
%Flop{}

iex> reset_cursors(%Flop{before: "A"})
%Flop{}
Link to this function

reset_filters(flop)

View Source (since 0.15.0)
@spec reset_filters(t()) :: t()

Removes all filters from a Flop struct.

example

Example

iex> reset_filters(%Flop{filters: [
...>   %Flop.Filter{field: :name, value: "Jim"}
...> ]})
%Flop{filters: []}
Link to this function

reset_order(flop)

View Source (since 0.15.0)
@spec reset_order(t()) :: t()

Removes the order parameters from a Flop struct.

example

Example

iex> reset_order(%Flop{order_by: [:name], order_directions: [:asc]})
%Flop{order_by: nil, order_directions: nil}
Link to this function

run(q, flop, opts \\ [])

View Source (since 0.6.0)
@spec run(Ecto.Queryable.t(), t(), [option()]) :: {[any()], Flop.Meta.t()}

Applies the given Flop to the given queryable, retrieves the data and the meta data.

This function does not validate the given flop parameters. You can validate the parameters with Flop.validate/2 or Flop.validate!/2, or you can use Flop.validate_and_run/3 or Flop.validate_and_run!/3 instead of this function.

iex> {data, meta} = Flop.run(Flop.Pet, %Flop{})
iex> data == []
true
iex> match?(%Flop.Meta{}, meta)
true

See the documentation for Flop.validate_and_run/3 for supported options.

Link to this function

set_cursor(meta, atom)

View Source (since 0.15.0)
@spec set_cursor(Flop.Meta.t(), :previous | :next) :: t()

Takes a Flop.Meta struct and returns a Flop struct with updated cursor pagination params for going to either the previous or the next page.

See to_previous_cursor/1 and to_next_cursor/1 for details.

examples

Examples

iex> set_cursor(
...>   %Flop.Meta{
...>     flop: %Flop{first: 5, after: "a"},
...>     has_previous_page?: true, start_cursor: "b"
...>   },
...>   :previous
...> )
%Flop{last: 5, before: "b"}

iex> set_cursor(
...>   %Flop.Meta{
...>     flop: %Flop{first: 5, after: "a"},
...>     has_next_page?: true, end_cursor: "b"
...>   },
...>   :next
...> )
%Flop{first: 5, after: "b"}
Link to this function

set_offset(flop, offset)

View Source (since 0.15.0)
@spec set_offset(t(), non_neg_integer() | binary()) :: t()

Sets the offset value of a Flop struct while also removing/converting pagination parameters for other pagination types.

iex> set_offset(%Flop{limit: 10, offset: 10}, 20)
%Flop{offset: 20, limit: 10}

iex> set_offset(%Flop{page: 5, page_size: 10}, 20)
%Flop{limit: 10, offset: 20, page: nil, page_size: nil}

iex> set_offset(%Flop{limit: 10, offset: 10}, "20")
%Flop{offset: 20, limit: 10}

The offset will not be allowed to go below 0.

iex> set_offset(%Flop{}, -5)
%Flop{offset: 0}
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set_page(flop, page)

View Source (since 0.12.0)
@spec set_page(t(), pos_integer() | binary()) :: t()

Sets the page value of a Flop struct while also removing/converting pagination parameters for other pagination types.

iex> set_page(%Flop{page: 2, page_size: 10}, 6)
%Flop{page: 6, page_size: 10}

iex> set_page(%Flop{limit: 10, offset: 20}, 8)
%Flop{limit: nil, offset: nil, page: 8, page_size: 10}

iex> set_page(%Flop{page: 2, page_size: 10}, "6")
%Flop{page: 6, page_size: 10}

The page number will not be allowed to go below 1.

iex> set_page(%Flop{}, -5)
%Flop{page: 1}
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to_next_cursor(meta)

View Source (since 0.15.0)
@spec to_next_cursor(Flop.Meta.t()) :: t()

Takes a Flop.Meta struct and returns a Flop struct with updated cursor pagination params for going to the next page.

If there is no next page, the Flop struct is return unchanged.

examples

Examples

iex> to_next_cursor(
...>   %Flop.Meta{
...>     flop: %Flop{first: 5, after: "a"},
...>     has_next_page?: true, end_cursor: "b"
...>   }
...> )
%Flop{first: 5, after: "b"}

iex> to_next_cursor(
...>   %Flop.Meta{
...>     flop: %Flop{last: 5, before: "b"},
...>     has_next_page?: true, end_cursor: "a"
...>   }
...> )
%Flop{first: 5, after: "a"}

iex> to_next_cursor(
...>   %Flop.Meta{
...>     flop: %Flop{first: 5, after: "a"},
...>     has_next_page?: false, start_cursor: "b"
...>   }
...> )
%Flop{first: 5, after: "a"}
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to_next_offset(flop, total_count \\ nil)

View Source (since 0.15.0)
@spec to_next_offset(t(), non_neg_integer() | nil) :: t()

Sets the offset of a Flop struct to the next page depending on the limit.

If the total count is given as the second argument, the offset will not be increased if the last page has already been reached. You can get the total count from the Flop.Meta struct. If the Flop has an offset beyond the total count, the offset will be set to the last page.

examples

Examples

iex> to_next_offset(%Flop{offset: 10, limit: 5})
%Flop{offset: 15, limit: 5}

iex> to_next_offset(%Flop{offset: 15, limit: 5}, 21)
%Flop{offset: 20, limit: 5}

iex> to_next_offset(%Flop{offset: 15, limit: 5}, 20)
%Flop{offset: 15, limit: 5}

iex> to_next_offset(%Flop{offset: 28, limit: 5}, 22)
%Flop{offset: 20, limit: 5}

iex> to_next_offset(%Flop{offset: -5, limit: 20})
%Flop{offset: 0, limit: 20}
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to_next_page(flop, total_pages \\ nil)

View Source (since 0.15.0)
@spec to_next_page(t(), non_neg_integer() | nil) :: t()

Sets the page of a Flop struct to the next page.

If the total number of pages is given as the second argument, the page number will not be increased if the last page has already been reached. You can get the total number of pages from the Flop.Meta struct.

examples

Examples

iex> to_next_page(%Flop{page: 5})
%Flop{page: 6}

iex> to_next_page(%Flop{page: 5}, 6)
%Flop{page: 6}

iex> to_next_page(%Flop{page: 6}, 6)
%Flop{page: 6}

iex> to_next_page(%Flop{page: 7}, 6)
%Flop{page: 6}

iex> to_next_page(%Flop{page: -5})
%Flop{page: 1}
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to_previous_cursor(meta)

View Source (since 0.15.0)
@spec to_previous_cursor(Flop.Meta.t()) :: t()

Takes a Flop.Meta struct and returns a Flop struct with updated cursor pagination params for going to the previous page.

If there is no previous page, the Flop struct is return unchanged.

examples

Examples

iex> to_previous_cursor(
...>   %Flop.Meta{
...>     flop: %Flop{first: 5, after: "a"},
...>     has_previous_page?: true, start_cursor: "b"
...>   }
...> )
%Flop{last: 5, before: "b"}

iex> to_previous_cursor(
...>   %Flop.Meta{
...>     flop: %Flop{last: 5, before: "b"},
...>     has_previous_page?: true, start_cursor: "a"
...>   }
...> )
%Flop{last: 5, before: "a"}

iex> to_previous_cursor(
...>   %Flop.Meta{
...>     flop: %Flop{first: 5, after: "b"},
...>     has_previous_page?: false, start_cursor: "a"
...>   }
...> )
%Flop{first: 5, after: "b"}
Link to this function

to_previous_offset(flop)

View Source (since 0.15.0)
@spec to_previous_offset(t()) :: t()

Sets the offset of a Flop struct to the page depending on the limit.

examples

Examples

iex> to_previous_offset(%Flop{offset: 20, limit: 10})
%Flop{offset: 10, limit: 10}

iex> to_previous_offset(%Flop{offset: 5, limit: 10})
%Flop{offset: 0, limit: 10}

iex> to_previous_offset(%Flop{offset: 0, limit: 10})
%Flop{offset: 0, limit: 10}

iex> to_previous_offset(%Flop{offset: -2, limit: 10})
%Flop{offset: 0, limit: 10}
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to_previous_page(flop)

View Source (since 0.15.0)
@spec to_previous_page(t()) :: t()

Sets the page of a Flop struct to the previous page, but not less than 1.

examples

Examples

iex> to_previous_page(%Flop{page: 5})
%Flop{page: 4}

iex> to_previous_page(%Flop{page: 1})
%Flop{page: 1}

iex> to_previous_page(%Flop{page: -2})
%Flop{page: 1}
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validate!(flop_or_map, opts \\ [])

View Source (since 0.5.0)
@spec validate!(t() | map(), [option()]) :: t()

Same as Flop.validate/2, but raises an Ecto.InvalidChangesetError if the parameters are invalid.

Link to this function

validate(flop_or_map, opts \\ [])

View Source
@spec validate(t() | map(), [option()]) :: {:ok, t()} | {:error, Flop.Meta.t()}

Validates a Flop.t/0.

examples

Examples

iex> params = %{"limit" => 10, "offset" => 0, "texture" => "fluffy"}
iex> Flop.validate(params)
{:ok,
 %Flop{
   filters: [],
   limit: 10,
   offset: 0,
   order_by: nil,
   order_directions: nil,
   page: nil,
   page_size: nil
 }}

iex> flop = %Flop{offset: -1}
iex> {:error, %Flop.Meta{} = meta} = Flop.validate(flop)
iex> meta.errors
[
  offset: [
    {"must be greater than or equal to %{number}",
     [validation: :number, kind: :greater_than_or_equal_to, number: 0]}
  ]
]

It also makes sure that only one pagination method is used.

iex> params = %{limit: 10, offset: 0, page: 5, page_size: 10}
iex> {:error, %Flop.Meta{} = meta} = Flop.validate(params)
iex> meta.errors
[limit: [{"cannot combine multiple pagination types", []}]]

If you derived Flop.Schema in your Ecto schema to define the filterable and sortable fields, you can pass the module name to the function to validate that only allowed fields are used. The function will also apply any default values set for the schema.

iex> params = %{"order_by" => ["species"]}
iex> {:error, %Flop.Meta{} = meta} = Flop.validate(params, for: Flop.Pet)
iex> [order_by: [{msg, [_, {_, enum}]}]] = meta.errors
iex> msg
"has an invalid entry"
iex> enum
[:name, :age, :owner_name, :owner_age]

Note that currently, trying to use an existing field that is not allowed as seen above will result in the error message has an invalid entry, while trying to use a field name that does not exist in the schema (or more precisely: a field name that doesn't exist as an atom) will result in the error message is invalid. This might change in the future.

Link to this function

validate_and_run!(q, map_or_flop, opts \\ [])

View Source (since 0.6.0)
@spec validate_and_run!(Ecto.Queryable.t(), map() | t(), [option()]) ::
  {[any()], Flop.Meta.t()}

Same as Flop.validate_and_run/3, but raises on error.

Link to this function

validate_and_run(q, map_or_flop, opts \\ [])

View Source (since 0.6.0)
@spec validate_and_run(Ecto.Queryable.t(), map() | t(), [option()]) ::
  {:ok, {[any()], Flop.Meta.t()}} | {:error, Flop.Meta.t()}

Validates the given flop parameters and retrieves the data and meta data on success.

iex> {:ok, {[], %Flop.Meta{}}} =
...>   Flop.validate_and_run(Flop.Pet, %Flop{}, for: Flop.Pet)
iex> {:error, %Flop.Meta{} = meta} =
...>   Flop.validate_and_run(Flop.Pet, %Flop{limit: -1})
iex> meta.errors
[
  limit: [
    {"must be greater than %{number}",
     [validation: :number, kind: :greater_than, number: 0]}
  ]
]

options

Options

  • for: Passed to Flop.validate/2.
  • repo: The Ecto.Repo module. Required if no default repo is configured.
  • cursor_value_func: An arity-2 function to be used to retrieve an unencoded cursor value from a query result item and the order_by fields. Defaults to Flop.Cursor.get_cursor_from_node/2.
  • count_query: Lets you override the base query for counting, e.g. if you don't want to include unnecessary joins. The filter parameters are applied to the given query. See also Flop.count/3.