Ecto Schema Store

This library is used to create customizable data stores for individual ecto schemas.

With the following schema:

defmodule Person do
  use EctoTest.Web, :model

  schema "people" do
    field :name, :string
    field :email, :string

    timestamps
  end

  def changeset(model, params) do
    model
    |> cast(params, [:name, :email])
  end
end

You can create a store with the following:

defmodule PersonStore do
  use EctoSchemaStore, schema: Person, repo: MyApp.Repo
end

Querying

The following functions are provided in a store for retrieving data.

• all - Fetch all records
• one - Return a single record
• refresh - Reloads an existing record from the database.
• preload_assocs - Preload record associations. Same as Repo.preload. Providing :all will cause all associations to be preloaded.
• count_records - Count the number of records returned by the provided filters.
• exists? - Returns true if any records exists for the provided filters.
• destructure - Return the model as generic Elixir maps without the Ecto content

Sample Queries:

# Get all records in a table.
PersonStore.all

# Get all records fields that match the provided value.
PersonStore.all %{name: "Bob"}
PersonStore.all %{name: "Bob", email: "bob@nowhere.test"}
PersonStore.all name: "Bob", email: "bob@nowhere.test"

# Return a single record.
PersonStore.one %{name: "Bob"}
PersonStore.one name: "Bob"

# Return a specific record by id.
PersonStore.one 12

# Refresh
record = PersonStore.one 12
record = PersonStore.refresh record

# Preload after query
PersonStore.preload_assocs record, :field_name
PersonStore.preload_assocs record, :all
PersonStore.preload_assocs record, [:field_name_1, :field_name_2]

# Destructure
record = Person.destructure Person.one 12

Options:

• preload - An atom or list of atoms with the model association keys to preload. Providing :all will cause all associations to be preloaded.
• destructure - Return the models as generic Elixir maps without the Ecto content. Defaults: false

# Get all records in a table.
PersonStore.all %{}, preload: :field_name

# Get all records fields that match the provided value.
PersonStore.all %{name: "Bob"}, preload: [:field_name_1, :field_name_2]

# Return a single record.
PersonStore.one %{name: "Bob"}, preload: :all

# Return a specific record by id.
PersonStore.one 12, preload: :all, destructure: true

Filter Operators

Stores support a special syntax for changing the comparison operator in the passed filter map or keyword list.

Operators:

• {:==, value} - The field equals this value. This is the default operator when the value is not nil.
• {:!=, value} - The field does not equal the value.
• {:==, nil} - The field is nil or null in the database. This is the default operator when the value is nil.
• {:!=, nil} - The field is not nil or null in the database.
• {:<, value} - The field is less than the value.
• {:<=, value} - The field is less than or equal the value.
• {:>, value} - The field is greater than the value.
• {:>=, value} - The field is greater than or equal the value.
• {:in, []} - the field is in the list of provided values.

PersonStore.all %{name: nil}
PersonStore.all %{name: {:==, nil}}
PersonStore.all name: {:!=, nil}
PersonStore.all name: {:!=, "Bob"}
PersonStore.all name: {:in, ["Bob"]}, email: "bob@nowhere.test"

Editing

The following functions are provided in a store for editing data.

• insert - Insert a record based upon supplied parameters map.
• insert_fields - Insert the record without using a changeset.
• insert! - Same as insert but throws an error instead of returning a tuple.
• insert_fields! - Same as insert_fields but throws an error instead of returning a tuple.
• update - Update a record based upon supplied parameters map.
• update_fields - Update the record without using a changeset.
• update! - Same as update but throws an error instead of returning a tuple.
• update_fields! - Same as update_fields but throws an error instead of returning a tuple.
• update_or_create - Updates a record if the provided query values are found. Otherwise creates the record.
• update_or_create! - Same as update_or_create but throws an error instead of returning a tuple.
• update_or_create_fields - Updates a record if the provided query values are found. Otherwise creates the record. Does not use a changeset.
• update_or_create_fields! - Same as update_or_create_fields but throws an error instead of returning a tuple.
• delete - Delete a record.
• delete! - Same as delete but throws an error instead of returning a tuple.

Sample Usage:

# Using Map
bob = PersonStore.insert! %{name: "Bob", email: "bob@nowhere.test"}
bob = PersonStore.update! bob, %{email: "bob2@nowhere.test"}
PersonStore.delete bob

# Using Keyword List
bob = PersonStore.insert! name: "Bob", email: "bob@nowhere.test"
bob = PersonStore.update! bob, email: "bob2@nowhere.test"

# Updates/deletes can also occur by id.
PersonStore.update! 12, %{email: "bob2@nowhere.test"}
PersonStore.delete 12

# Update or create
attributes_to_update = 
query = %{name: "Bob"}
PersonStore.update_or_create attributes_to_update, query
PersonStore.update_or_create! %{email: "new@nowhere.test"}, name: "Bob"

Changesets

The insert and update functions by default use a changeset on the provided schema name :changeset for inserting and updating. This can be overridden and a specific changeset name provided.

bob = PersonStore.insert! %{name: "Bob", email: "bob@nowhere.test"}, changeset: :insert_changeset
bob = PersonStore.insert! [name: "Bob", email: "bob@nowhere.test"], changeset: :insert_changeset
bob = PersonStore.update! bob, %{email: "bob2@nowhere.test"}, changeset: :update_changeset
bob = PersonStore.update! bob, [email: "bob2@nowhere.test"], changeset: :update_changeset
bob = PersonStore.update! bob, %{email: "bob2@nowhere.test"}, changeset: :my_other_custom_changeset

It is also possible to pass a function reference in as the changeset.

def my_changeset(model, params) do
  model
  |> cast(params, [:name, :email])
  |> validate_required([:name])
end

insert [name: "Bob"], changeset: &my_changeset/2

References

The internal references to the schema and the provided Ecto Repo are provided as convience functions.

• schema - returns the schema reference used internally by the store.
• repo - returns the Ecto Repo reference used internally by the store.

Custom Actions

Since a store is just an ordinary module, you can add your actions and build off private APIs to the store. For convience Ecto.Query is already fully imported into the module.

A store is provided the following custom internal API:

• build_query - Builds a Ecto.Query struct based upon the map params input.

defmodule PersonStore do
  use EctoSchemaStore, schema: Person, repo: MyApp.Repo

  def get_all_ordered_by_name do
    build_query
    |> order_by([:name])
    |> all
  end

  def find_by_email(email) do
    %{email: email}
    |> build_query
    |> order_by([:name])
    |> all
  end

  def get_all_ordered_by_name_using_ecto_directly do
    query = from p in schema,
            order_by: [p.name]
    
    repo.all query
  end
end

Schema Field Aliases

Sometimes field names get changed or the developer wishes to have an alias that represents another field. These work for both querying and editing schema models.

defmodule PersonStore do
  use EctoSchemaStore, schema: Person, repo: MyApp.Repo

  alias_fields email_address: :email
end

PersonStore.all %{email_address: "bob@nowhere.test"}
PersonStore.update! 12, %{email_address: "bob@nowhere.test"}

Filter or Params Map/Keyword List

Many of the API calls used by a store take a map of fields as input. Normal Ecto requires param maps to be either all atom or string keyed but not mixed. A schema store will convert every map provided into atom keys before aliasing and passing on to Ecto. This means you can provide a mixture of both. This will allow a developer to combine multiple maps together and not worry about what kind of keys were used.

However, if you provide the same value twice as both an atom and string key then only one will be used.

PersonStore.insert! %{"name" => "Bob", email: "bob2@nowhere.test"}

Lexical Atom Query

The store provides a function for taking a lexical query atom with a list of values and returning the results. Currently only supports _and_ clauses.

Functions:

• get_all_by - Return all results. Equivalent to using the all function.
• get_by - Return a single result. Equivalent to using the one function.

# Regular
PersonStore.all %{name: "Bob", email: "bob@nowhere.test"}
# Lexical Atom
PersonStore.get_all_by :name_and_email, ["Bob", "bob@nowhere.test"]

# Regular
PersonStore.one %{name: "Bob", email: "bob@nowhere.test"}
# Lexical Atom
PersonStore.get_by :name_and_email, ["Bob", "bob@nowhere.test"]

Edit Events

A store supports the concept of an event after an edit action is successful in the Ecto repo.

Events:

• :after_insert
• :after_update
• :after_delete

defmodule PersonStore do
  use EctoSchemaStore, schema: Person, repo: MyApp.Repo

  on(:after_delete, model) do
    IO.inspect "Delete #{schema} id: #{model.id}"
  end

  on([:after_insert, :after_update], model) do
    IO.inspect "Changed #{schema} id: #{model.id}"
  end
end