View Source Exto (exto v0.3.0)

Configuration-driven Ecto Schemata.



Adds additional associations dynamically from app config.


Link to this macro


View Source (macro)

Adds additional associations dynamically from app config.

Reads config for the given OTP application, under the name of the current module. Each key maps to an Ecto.Schema function:

  • belongs_to
  • field
  • has_many
  • has_one
  • many_to_many

Each of these keys should map to a keyword list where the key is the name of the field or association and the value is one of:

  • A type
  • A tuple of type and options (keyword list)

Example Schema:

defmodule My.Schema do
  use Ecto.Schema
  import Exto, only: [flex_schema: 1]

  schema "my_table" do
    field :name, :string # just normal schema things
    flex_schema(:my_app) # boom! give me the stuff

Example configuration:

config :my_app, My.Schema,
  belongs_to: [
    foo: Foo,                   # belongs_to :foo, Foo
    bar: {Bar, type: :integer}, # belongs_to :bar, Bar, type: :integer
  field: [
    foo: :string,                # field :foo, :string
    bar: {:integer, default: 4}, # field :foo, :integer, default: 4
  has_one: [
    foo: Foo,                             # has_one :foo, Foo
    bar: {Bar, foreign_key: :the_bar_id}, # has_one :bar, Bar, foreign_key: :the_bar_id
  has_many: [
    foo: Foo,                             # has_many :foo, Foo
    bar: {Bar, foreign_key: :the_bar_id}, # has_many :bar, Bar, foreign_key: :the_bar_id
  many_to_many: [
    foo: Foo,                         # many_to_many :foo, Foo
    bar: {Bar, join_through: FooBar}, # many_to_many :bar, Bar, :join_through: FooBar

This one won't work very well because we define foo and bar 5 times each, but I think you get the point.

Reading of configuration is done during compile time. The relations will be baked in during compilation, thus:

  • Do not expect this to work in runtime config.
  • You will need to rebuild all dependencies which use this macro when you change their configuration.