Ecto v2.0.0-rc.5 Ecto.Repo behaviour

Defines a repository.

A repository maps to an underlying data store, controlled by the adapter. For example, Ecto ships with a Postgres adapter that stores data into a PostgreSQL database.

When used, the repository expects the :otp_app as option. The :otp_app should point to an OTP application that has the repository configuration. For example, the repository:

defmodule Repo do
  use Ecto.Repo, otp_app: :my_app
end

Could be configured with:

config :my_app, Repo,
  adapter: Ecto.Adapters.Postgres,
  database: "ecto_simple",
  username: "postgres",
  password: "postgres",
  hostname: "localhost"

Most of the configuration that goes into the config is specific to the adapter, so check Ecto.Adapters.Postgres documentation for more information. However, some configuration is shared across all adapters, they are:

  • :priv - the directory where to keep repository data, like migrations, schema and more. Defaults to “priv/YOUR_REPO”

  • :url - an URL that specifies storage information. Read below for more information

  • :loggers - a list of {mod, fun, args} tuples that are invoked by adapters for logging queries and other events. The given module and function will be called with a log entry (see Ecto.LogEntry) and the given arguments. The invoked function must return the Ecto.LogEntry as result. The default value is: [{Ecto.LogEntry, :log, []}], which will call Ecto.LogEntry.log/1 that will use Elixir’s Logger in :debug mode. You may pass any desired mod-fun-args triplet or [{Ecto.LogEntry, :log, [:info]}] if you want to keep the current behaviour but use another log level.

URLs

Repositories by default support URLs. For example, the configuration above could be rewritten to:

config :my_app, Repo,
  url: "ecto://postgres:postgres@localhost/ecto_simple"

The schema can be of any value. The path represents the database name while options are simply merged in.

URLs also support {:system, "KEY"} to be given, telling Ecto to load the configuration from the system environment instead:

config :my_app, Repo,
  url: {:system, "DATABASE_URL"}

Shared options

Almost all of the repository operations below accept the following options:

  • :timeout - The time in milliseconds to wait for the query call to finish, :infinity will wait indefinitely (default: 15000);
  • :pool_timeout - The time in milliseconds to wait for calls to the pool to finish, :infinity will wait indefinitely (default: 5000);
  • :log - When false, does not log the query

Such cases will be explicitly documented as well as any extra option.

Summary

Callbacks

Returns the adapter tied to the repository

A callback invoked by adapters that logs the given action

Calculate the given aggregate over the given field

Fetches all entries from the data store matching the given query

Returns the adapter configuration stored in the :otp_app environment

Deletes a struct using its primary key

Same as delete/2 but returns the struct or raises if the changeset is invalid

Deletes all entries matching the given query

Fetches a single struct from the data store where the primary key matches the given id

Similar to get/3 but raises Ecto.NoResultsError if no record was found

Fetches a single result from the query

Similar to get_by/3 but raises Ecto.NoResultsError if no record was found

Returns true if the current process is inside a transaction

Inserts a struct or a changeset

Same as insert/2 but returns the struct or raises if the changeset is invalid

Inserts all entries into the repository

Inserts or updates a changeset depending on whether the struct is persisted or not

Same as insert_or_update/2 but returns the struct or raises if the changeset is invalid

Fetches a single result from the query

Similar to one/2 but raises Ecto.NoResultsError if no record was found

Preloads all associations on the given struct or structs

Rolls back the current transaction

Starts any connection pooling or supervision and return {:ok, pid} or just :ok if nothing needs to be done

Shuts down the repository represented by the given pid

Runs the given function or Ecto.Multi inside a transaction

Updates a changeset using its primary key

Same as update/2 but returns the struct or raises if the changeset is invalid

Updates all entries matching the given query with the given values

Types

t :: module

Callbacks

__adapter__()

Specs

__adapter__ :: Ecto.Adapter.t

Returns the adapter tied to the repository.

__log__(arg0)

Specs

A callback invoked by adapters that logs the given action.

See Ecto.LogEntry for more information and Ecto.Repo module documentation on setting up your own loggers.

aggregate(arg0, aggregate, field, arg3)

Specs

aggregate(Ecto.Queryable.t, aggregate :: :avg | :count | :max | :min | :sum, field :: atom, Keyword.t) ::
  term |
  nil

Calculate the given aggregate over the given field.

If the query has a limit, offset or distinct set, it will be automatically wrapped in a subquery in order to return the proper result.

Any preload or select in the query will be ignored in favor of the column being aggregated.

The aggregation will fail if any group_by field is set.

Options

See the “Shared options” section at the module documentation.

Examples

# Returns the number of visits per blog post
Repo.aggregate(Post, :avg, :visits)

# Returns the average number of visits for the top 10
query = from Post, limit: 10
Repo.aggregate(query, :avg, :visits)
all(queryable, opts)

Specs

all(queryable :: Ecto.Query.t, opts :: Keyword.t) ::
  [Ecto.Schema.t] |
  no_return

Fetches all entries from the data store matching the given query.

May raise Ecto.QueryError if query validation fails.

Options

See the “Shared options” section at the module documentation.

Example

# Fetch all post titles
query = from p in Post,
     select: p.title
MyRepo.all(query)
config()

Specs

config :: Keyword.t

Returns the adapter configuration stored in the :otp_app environment.

delete(arg0, arg1)

Specs

delete(Ecto.Schema.t, Keyword.t) ::
  {:ok, Ecto.Schema.t} |
  {:error, Ecto.Changeset.t}

Deletes a struct using its primary key.

If the struct has no primary key, Ecto.NoPrimaryKeyFieldError will be raised.

It returns {:ok, struct} if the struct has been successfully deleted or {:error, changeset} if there was a validation or a known constraint error.

Options

See the “Shared options” section at the module documentation.

Example

post = MyRepo.get!(Post, 42)
case MyRepo.delete post do
  {:ok, struct}       -> # Deleted with success
  {:error, changeset} -> # Something went wrong
end
delete!(arg0, arg1)

Specs

delete!(Ecto.Schema.t, Keyword.t) ::
  Ecto.Schema.t |
  no_return

Same as delete/2 but returns the struct or raises if the changeset is invalid.

delete_all(queryable, options)

Specs

delete_all(queryable :: Ecto.Queryable.t, options :: Keyword.t) ::
  {integer, nil | [term]} |
  no_return

Deletes all entries matching the given query.

It returns a tuple containing the number of entries and any returned result as second element. If the database does not support RETURNING in DELETE statements or no return result was selected, the second element will be nil.

Options

  • :returning - selects which fields to return. When true, returns all fields in the given struct. May be a list of fields, where a struct is still returned but only with the given fields. Or false, where nothing is returned (the default). This option is not supported by all databases.

See the “Shared options” section at the module documentation for remaining options.

Examples

MyRepo.delete_all(Post)

from(p in Post, where: p.id < 10) |> MyRepo.delete_all
get(arg0, term, arg2)

Specs

get(Ecto.Queryable.t, term, Keyword.t) ::
  Ecto.Schema.t |
  nil |
  no_return

Fetches a single struct from the data store where the primary key matches the given id.

Returns nil if no result was found. If the struct in the queryable has no or more than one primary key, it will raise an argument error.

Options

See the “Shared options” section at the module documentation.

Example

MyRepo.get(Post, 42)
get!(arg0, term, arg2)

Specs

get!(Ecto.Queryable.t, term, Keyword.t) ::
  Ecto.Schema.t |
  nil |
  no_return

Similar to get/3 but raises Ecto.NoResultsError if no record was found.

Options

See the “Shared options” section at the module documentation.

Example

MyRepo.get!(Post, 42)
get_by(arg0, arg1, arg2)

Specs

get_by(Ecto.Queryable.t, Keyword.t | Map.t, Keyword.t) ::
  Ecto.Schema.t |
  nil |
  no_return

Fetches a single result from the query.

Returns nil if no result was found.

Options

See the “Shared options” section at the module documentation.

Example

MyRepo.get_by(Post, title: "My post")
get_by!(arg0, arg1, arg2)

Specs

get_by!(Ecto.Queryable.t, Keyword.t | Map.t, Keyword.t) ::
  Ecto.Schema.t |
  nil |
  no_return

Similar to get_by/3 but raises Ecto.NoResultsError if no record was found.

Options

See the “Shared options” section at the module documentation.

Example

MyRepo.get_by!(Post, title: "My post")
in_transaction?()

Specs

in_transaction? :: boolean

Returns true if the current process is inside a transaction.

Examples

MyRepo.in_transaction?
#=> false

MyRepo.transaction(fn ->
  MyRepo.in_transaction? #=> true
end)
insert(arg0, arg1)

Specs

Inserts a struct or a changeset.

In case a struct is given, the struct is converted into a changeset with all non-nil fields as part of the changeset.

In case a changeset is given, the changes in the changeset are merged with the struct fields, and all of them are sent to the database.

It returns {:ok, struct} if the struct has been successfully inserted or {:error, changeset} if there was a validation or a known constraint error.

Options

See the “Shared options” section at the module documentation.

Example

case MyRepo.insert %Post{title: "Ecto is great"} do
  {:ok, struct}       -> # Inserted with success
  {:error, changeset} -> # Something went wrong
end
insert!(arg0, arg1)

Specs

insert!(Ecto.Schema.t, Keyword.t) ::
  Ecto.Schema.t |
  no_return

Same as insert/2 but returns the struct or raises if the changeset is invalid.

insert_all(arg0, list, opts)

Specs

insert_all(binary | {binary | nil, binary} | Ecto.Schema.t, [map | Keyword.t], opts :: Keyword.t) ::
  {integer, nil | [term]} |
  no_return

Inserts all entries into the repository.

It expects a schema (MyApp.User) or a source ("users" or {"prefix", "users"}) as the first argument. The second argument is a list of entries to be inserted, either as keyword lists or as maps.

When a schema is given, the values given will be properly dumped before being sent to the database. If the schema contains an autogenerated ID field, it will be handled either at the adapter or the storage layer. However any other autogenerated value, like timestamps, won’t be autogenerated when using c:insert_all/3. This is by design as this function aims to be a more direct way to insert data into the database without the conveniences of c:insert/2. This is also consistent with c:update_all/3 that does not handle timestamps as well.

If a source is given, without a schema, the given fields are passed as is to the adapter.

Options

See the “Shared options” section at the module documentation.

insert_or_update(arg0, arg1)

Specs

insert_or_update(Ecto.Changeset.t, Keyword.t) ::
  {:ok, Ecto.Schema.t} |
  {:error, Ecto.Changeset.t}

Inserts or updates a changeset depending on whether the struct is persisted or not.

The distinction whether to insert or update will be made on the Ecto.Schema.Metadata field :state. The :state is automatically set by Ecto when loading or building a schema.

Please note that for this to work, you will have to load existing structs from the database. So even if the struct exists, this won’t work:

struct = %Post{id: 'existing_id', ...}
MyRepo.insert_or_update changeset
# => {:error, "id already exists"}

Options

See the “Shared options” section at the module documentation.

Example

result =
  case MyRepo.get(Post, id) do
    nil  -> %Post{id: id} # Post not found, we build one
    post -> post          # Post exists, let's use it
  end
  |> Post.changeset(changes)
  |> MyRepo.insert_or_update

case result do
  {:ok, struct}       -> # Inserted or updated with success
  {:error, changeset} -> # Something went wrong
end
insert_or_update!(arg0, arg1)

Specs

insert_or_update!(Ecto.Changeset.t, Keyword.t) ::
  Ecto.Schema.t |
  no_return

Same as insert_or_update/2 but returns the struct or raises if the changeset is invalid.

one(arg0, arg1)

Specs

one(Ecto.Queryable.t, Keyword.t) ::
  Ecto.Schema.t |
  nil |
  no_return

Fetches a single result from the query.

Returns nil if no result was found. Raises if more than one entry.

Options

See the “Shared options” section at the module documentation.

one!(arg0, arg1)

Specs

one!(Ecto.Queryable.t, Keyword.t) ::
  Ecto.Schema.t |
  no_return

Similar to one/2 but raises Ecto.NoResultsError if no record was found.

Raises if more than one entry.

Options

See the “Shared options” section at the module documentation.

preload(struct_or_structs, preloads, opts)

Specs

preload(struct_or_structs, preloads :: term, opts :: Keyword.t) :: struct_or_structs when struct_or_structs: [Ecto.Schema.t] | Ecto.Schema.t

Preloads all associations on the given struct or structs.

This is similar to Ecto.Query.preload/3 except it allows you to preload structs after they have been fetched from the database.

In case the association was already loaded, preload won’t attempt to reload it.

Options

Besides the “Shared options” section at the module documentation, it accepts:

  • :force - By default, Ecto won’t preload associations that are already loaded. By setting this option to true, any existing association will be discarded and reloaded.
  • :in_parallel - If the preloads must be done in parallel. It can only be performed when we have more than one preload and the repository is not in a transaction. Defaults to true.
  • :prefix - the prefix to fetch preloads from. By default, queries will use the same prefix as the one in the given collection. This option allows the prefix to be changed.

Examples

posts = Repo.preload posts, :comments
posts = Repo.preload posts, comments: :permalinks
posts = Repo.preload posts, comments: from(c in Comment, order_by: c.published_at)
rollback(any)

Specs

rollback(any) :: no_return

Rolls back the current transaction.

The transaction will return the value given as {:error, value}.

start_link()

Specs

start_link ::
  {:ok, pid} |
  {:error, {:already_started, pid}} |
  {:error, term}

Starts any connection pooling or supervision and return {:ok, pid} or just :ok if nothing needs to be done.

Returns {:error, {:already_started, pid}} if the repo is already started or {:error, term} in case anything else goes wrong.

stop(pid, timeout)

Specs

stop(pid, timeout) :: :ok

Shuts down the repository represented by the given pid.

transaction(arg0, arg1)

Specs

transaction((... -> any) | Ecto.Multi.t, Keyword.t) ::
  {:ok, any} |
  {:error, any} |
  {:error, atom, any, %{atom => any}}

Runs the given function or Ecto.Multi inside a transaction.

Use with function

If an unhandled error occurs the transaction will be rolled back and the error will bubble up from the transaction function. If no error occurred the transaction will be committed when the function returns. A transaction can be explicitly rolled back by calling rollback/1, this will immediately leave the function and return the value given to rollback as {:error, value}.

A successful transaction returns the value returned by the function wrapped in a tuple as {:ok, value}.

If transaction/2 is called inside another transaction, the function is simply executed, without wrapping the new transaction call in any way. If there is an error in the inner transaction and the error is rescued, or the inner transaction is rolled back, the whole outer transaction is marked as tainted, guaranteeing nothing will be committed.

Use with Ecto.Multi

Besides functions transaction can be used with an Ecto.Multi struct. Transaction will be started, all operations applied and in case of success committed returning {:ok, changes}. In case of any errors the transaction will be rolled back and {:error, failed_operation, failed_value, changes_so_far} will be returned.

You can read more about using transactions with Ecto.Multi as well as see some examples in the Ecto.Multi documentation.

Options

See the “Shared options” section at the module documentation.

Examples

MyRepo.transaction(fn ->
  MyRepo.update!(%{alice | balance: alice.balance - 10})
  MyRepo.update!(%{bob | balance: bob.balance + 10})
end)

# Roll back a transaction explicitly
MyRepo.transaction(fn ->
  p = MyRepo.insert!(%Post{})
  if not Editor.post_allowed?(p) do
    MyRepo.rollback(:posting_not_allowed)
  end
end)

# With Ecto.Multi
Ecto.Multi.new
|> Ecto.Multi.insert(%Post{})
|> MyRepo.transaction
update(arg0, arg1)

Specs

update(Ecto.Changeset.t, Keyword.t) ::
  {:ok, Ecto.Schema.t} |
  {:error, Ecto.Changeset.t}

Updates a changeset using its primary key.

A changeset is required as it is the only for mechanism for tracking dirty changes.

If the struct has no primary key, Ecto.NoPrimaryKeyFieldError will be raised.

It returns {:ok, struct} if the struct has been successfully updated or {:error, changeset} if there was a validation or a known constraint error.

Options

Besides the “Shared options” section at the module documentation, it accepts:

  • :force - By default, if there are no changes in the changeset, update!/2 is a no-op. By setting this option to true, update callbacks will always be executed, even if there are no changes (including timestamps).

Example

post = MyRepo.get!(Post, 42)
post = Ecto.Changeset.change post, title: "New title"
case MyRepo.update post do
  {:ok, struct}       -> # Updated with success
  {:error, changeset} -> # Something went wrong
end
update!(arg0, arg1)

Specs

update!(Ecto.Schema.t, Keyword.t) ::
  Ecto.Schema.t |
  no_return

Same as update/2 but returns the struct or raises if the changeset is invalid.

update_all(queryable, updates, opts)

Specs

update_all(queryable :: Ecto.Queryable.t, updates :: Keyword.t, opts :: Keyword.t) ::
  {integer, nil | [term]} |
  no_return

Updates all entries matching the given query with the given values.

It returns a tuple containing the number of entries and any returned result as second element. If the database does not support RETURNING in UPDATE statements or no return result was selected, the second element will be nil.

Keep in mind this update_all will not update autogenerated fields like the updated_at columns.

See Ecto.Query.update/3 for update operations that can be performed on fields.

Options

  • :returning - selects which fields to return. When true, returns all fields in the given struct. May be a list of fields, where a struct is still returned but only with the given fields. Or false, where nothing is returned (the default). This option is not supported by all databases.

See the “Shared options” section at the module documentation for remaining options.

Examples

MyRepo.update_all(Post, set: [title: "New title"])

MyRepo.update_all(Post, inc: [visits: 1])

from(p in Post, where: p.id < 10)
|> MyRepo.update_all(set: [title: "New title"])

from(p in Post, where: p.id < 10, update: [set: [title: "New title"]])
|> MyRepo.update_all([])