absinthe v1.2.5 Absinthe.Type.Field
Used to define a field.
Usually these are defined using Absinthe.Schema.Notation.field/4
See the t
type below for details and examples of how to define a field.
Summary
Types
A custom error may be a map
or a Keyword.t
, but must contain a :message
key
An error message is a human-readable string describing the error that occurred
An error value is a simple error message, a custom error, or a list of either/both of them
A resolver function
The result of a resolver
Any serializable value
The configuration for a field
Functions
Build an AST of the field map for inclusion in other types
Types
custom_error :: %{:message => error_message, optional(atom) => serializable} | Keyword.t
A custom error may be a map
or a Keyword.t
, but must contain a :message
key.
Note that the values that make up a custom error must be serializable.
An error message is a human-readable string describing the error that occurred.
An error value is a simple error message, a custom error, or a list of either/both of them.
A resolver function.
See the Absinthe.Type.Field.t
explanation of :resolve
for more information.
The result of a resolver.
Any serializable value.
t :: %{name: binary, description: binary | nil, type: Absinthe.Type.identifier_t, deprecation: Absinthe.Type.Deprecation.t | nil, default_value: any, args: %{optional(binary | atom) => Absinthe.Type.Argument.t} | nil, resolve: resolver_t | nil, __private__: Keyword.t, __reference__: Absinthe.Type.Reference.t}
The configuration for a field.
:name
- The name of the field, usually assigned automatically by theAbsinthe.Schema.Notation.field/1
.:description
- Description of a field, useful for introspection.:deprecation
- Deprecation information for a field, usually set-up usingAbsinthe.Schema.Notation.deprecate/1
.:type
- The type the value of the field should resolve to:args
- The arguments of the field, usually created by usingAbsinthe.Schema.Notation.arg/2
.:resolve
- The resolution function. See below for more information.:default_value
- The default value of a field. Note this is not used during resolution; only fields that are part of anAbsinthe.Type.InputObject
should set this value.
Resolution Functions
Default
If no resolution function is given, the default resolution function is used, which is roughly equivalent to this:
{:ok, Map.get(parent_object, field_name)}
This is commonly use when listing the available fields on a
Absinthe.Type.Object
that models a data record. For instance:
object :person do
description "A person"
field :first_name, :string
field :last_name, :string
end
Custom Resolution
When accepting arguments, however, you probably need do use them for
something. Here’s an example of definining a field that looks up a list of
users for a given location_id
:
query do
field :users, :person do
arg :location_id, non_null(:id)
resolve fn %{location_id: id}, _ ->
{:ok, MyApp.users_for_location_id(id)}
end
end
end
Custom resolution functions are passed two arguments:
- A map of the arguments for the field, filled in with values from the provided query document/variables.
- An
Absinthe.Resolution
struct, containing the execution environment for the field (and useful for complex resolutions using the resolved source object, etc)
Functions
Build an AST of the field map for inclusion in other types
Examples
iex> build([foo: [type: :string], bar: [type: :integer]])
{:%{}, [],
[foo: {:%, [],
[{:__aliases__, [alias: false], [:Absinthe, :Type, :Field]},
{:%{}, [], [name: "Foo", type: :string]}]},
bar: {:%, [],
[{:__aliases__, [alias: false], [:Absinthe, :Type, :Field]},
{:%{}, [], [name: "Bar", type: :integer]}]}]}