Defines a Node schema.

a Node Schema is used to map a Neo4j node into an Elixir struct.

node/2 is used to map a Neo4j node into an Elixir struct and vice versa. It allows you to have your application data decoipled from your persisted data and to manipulate them easily.

Example

defmodule User do
  use Seraph.Schema.Node

  node "User" do
    property :name, :string
    property :age, :integer, default: 0

    incoming_relationship "FOLLOWED", MyApp.Blog.User, :followers, through: MyApp.Blog.Relationships.Followed

    outgoing_relationship "WROTE", MyApp.Blog.Post, :posts, through: MyApp.Blog.Relationships.Wrote
  end
end

By default, a node schema will generate a identifier which is named uuid and of type Ecto.UUID. This is to avoid to rely on Neo4j's internal ids for identifier purpose. The property macro defines a property in the node schema. The incoming_relationship macro defines relationship going from another node schema to the current one. The outgoing_relationship macro defines relationship going from the current node schema to another one. Schemas are regular structs and can be created and manipulated directly using Elixir's struct API:

iex> user = %User{name: "jane"}
iex> %{user | age: 30}

However, most commonly, structs are cast, validated and manipulated with the Seraph.Changeset module.

Schema attributes

Supported attributes for configuring the defined node schema. They must be set after the use Seraph.Schema.Node call and before the node/2 definition.

These attributes are:

• @identifier configures the node schema identifier. It will be used at node's creation only. It expects a tuple {name, type, options}. No options are available for the moment.
• @merge_keys configure the node schema merge keys. These keys will be used when updating the node data. It expects a list of atoms. Note that the merge keys must be properties of the node schema. If they are not defined, the identifier will be used as merge key.

Types

The available types are:

Reflection

Any node schema module will generate the __schema__ function that can be used for runtime introspection of the schema:

• __schema__(:primary_label) - Returns the primary label as defined in node/2
• __schema__(:identifier) - Returns the identifier data
• __schema__(:merge_keys) - Returns the list of merge keys
• __schema__(:properties) - Returns the list of properties names
• __schema__(:relationships) - Returns the list of all relationships data
• __schema__(:relationship, relationship_type) - Returns data about the specified relationship type
• __schema__(:incoming_relationships) - Returns a list of all incoming relationship names
• __schema__(:outgoing_relationships) - Returns a list of all outgoing relationship names