Filtery

Filtery help you to build the query using a syntax which is similar to Mongo This is super useful when you want to build filter from request params.

filter = %{
    status: "active",
    email: {:not, nil},
    role: ["admin", "moderator"]
}
Filtery.apply(User, filter)

Installation

Add filtery to your list of dependencies in mix.exs:

def deps do
  [
    {:filtery, "~> 0.2"}
  ]
end

Documentation is published here https://hexdocs.pm/filtery.

Table of Contents

Installation
I. Usage
II. Syntax
III. Supported operator
IV. Define your operators
V. Joining tables

I. Usage

Filtery help you to build the query using a similar syntax with MongoDB like this:

filter = %{
    status: "active",
    email: {:not, nil},
    role: ["admin", "moderator"]
}
Filtery.apply(User, filter)

The result is a query like this:

from(u in User, where: u.status == "active" and not is_nil(u.email) and u.role in ["admin", "moderator"])

II. Syntax

You can use <field>: <value> expressions to specify the equality condition and query operator expressions.

%{
  <field1>: <value1>,
  <field2>: { <operator>, <value> },
  ...
}

Notes: all operator belows are reserved keywords and cannot be used as field name

III. Supported operator

1. Comparition operator

`:eq`	Matches values that are equal to a specified value.
`:gt`	Matches values that are greater than a specified value.
`:gte`	Matches values that are greater than or equal to a specified value.
`:in`	Matches any of the values specified in an array.
`:lt`	Matches values that are less than a specified value.
`:lte`	Matches values that are less than or equal to a specified value.
`:ne`	Matches all values that are not equal to a specified value.
`:nin`	Matches none of the values specified in an array.

2. Logical operator

Name	Description
`:and`	Joins query clauses with a logical `AND` returns all documents that match the conditions of both clauses.
`:not`	Inverts the effect of a query expression and returns documents that do not match the query expression.

`:or`	Joins query clauses with a logical `OR` returns all documents that match the conditions of either clause.

`AND` operator

By default, if a map or keyword list is given, Filtery will join all field condition of that map using AND

Filtery.apply(User, %{status: "active", age: {:gt, 20}})

# same with
Filtery.apply(User, %{and:
                      %{status: "active", age: {:gt, 20}}
                      })

# same with
Filtery.apply(User, %{and:
                      [status: "active", age: {:gt, 20]}
                     })
                     
# same with
from(u in User, where: u.status == "active" and u.age > 20)

`OR` operator

The :or operator performs a logical OR operation on an array of two or more <expressions>

Filtery.apply(Product, %{or: %{
                           price: {:gt, 20},
                           category: "sport"
                         }})

`NOT` operator

Performs a logical NOT operation on the specified <operator-expression>

Syntax: %{ field: %{ not: <operator-expression> } }

Filtery.apply(Product, %{or: %{
                           price: {:gt, 20},
                           category: {:not: "sport"}
                         }})

Filtery.apply(Product, %{or: %{
                           price: {:not, {:gt, 20}},
                           category: "sport"
                         }})

3. Extra operator

Filtery provides some more useful operators to work with text and range.

Name	Description
`:between`	Matches values `>` lower bound and `<` upper bound
`:ibetween`	Matches values `>=` lower bound and `<=`upper bound
`like`, `contains`	Match values which contains specific value
`ilike`, `icontains`	Case insensitive version of `like`
`has`	For array type column, Matches array which has specific value

Syntax

between | ibetween
Syntax: field: {:between, [lower_value, upper_value]}

Check `NULL` and skip `nil` filter

By default is a value in the filter is nil, Filtery applies is_nil to check NULL value. You can tell Filtery to ignore all nil field by passing skip_nil: true to the options

Filtery.apply(query, filter, skip_nil: true)

In that case, if you want to check field which is NULL or NOT NULL you use :is_nil instead of nil when passing value to the filter:

Filter.apply(query, %{email: :is_nil}, skip_nil: true)

IV. Define your operators

You can extend Filtery and define your own operator. For example, here I define a new operatory equal

defmodule MyFiltery do
    use Filtery.Base
    
    def filter(column, {:equal, value}) do
    dynamic([q], field(q, ^column) == ^value)
    end
end

To support a filter, you must follow this spec

@spec filter(column::atom(), {operator::atom(), value::any()}) :: Ecto.Query.dynamic()

Within the body of filter/2 function using dynamic to compose your condtion and return a dynamic

V. Joining tables

Filtery defines a special operator ref to join table

Syntax: <field>: {:ref, <qualifier>, <filter on joined table>}

If qualifier is skipped, then :inner join is used by default.

query = Filtery.apply(Post, %{comments: {:ref, %{
                                    approved: true,
                                    content: {:like, "filtery"}
                                 }}})

And then you can use Name binding to do further query

query = where(query, [comments: c], c.published_at > ^xday_ago)

Qualifiers

By default Filtery join using :inner qualifier. You can use one of `:inner, :left, :right, :cross, :full, :inner_lateral or :left_lateral qualifier as defined by Ecto. ### You can filter with nested ref elixir Filtery.apply(Post, %{comments: {:ref, %{ approved: true, user: {:ref, %{ name: {:like, "Tom"} }} }}}) ### Important Notes on ref operator - Field name must be the association name in your schema because Filtery use assoc to build join query. In the above example, Post schema must define association has_many: :comments, Comment - Not allow 2 ref with same name because the name is used as alias :as in join query, so it can only use one.

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