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Add comprehensive directive support to DSL module (#563)
- `DSLDirective` class: Represents GraphQL directives with argument validation and AST generation - `DSLDirectable` mixin: Provides reusable `.directives()` method for all DSL elements that support directives - `DSLFragmentSpread` class: Represents fragment spreads with their own directives, separate from fragment definitions - Executable directive location support on query, mutation, subscription, fields, fragments, inline fragments, fragment spreads, and variable definitions ([spec](https://spec.graphql.org/October2021/#sec-Type-System.Directives)) - Automatic schema resolution: Fields automatically use their parent schema for custom directive validation - Fallback on builtin directives: Built-in directives are still available if a schema is not available to validate against The implementation follows the [October 2021 GraphQL specification](https://spec.graphql.org/October2021/) for executable directive locations and maintains backward compatibility with existing DSL code. Users can now use both built-in directives (`@skip`, `@include`) and custom schema directives across all supported GraphQL locations. Co-authored-by: Leszek Hanusz <leszek.hanusz@gmail.com>
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‎docs/advanced/dsl_module.rst‎

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@@ -64,11 +64,11 @@ from the :code:`ds` instance
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ds.Query.hero.select(ds.Character.name)
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The select method return the same instance, so it is possible to chain the calls::
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The select method returns the same instance, so it is possible to chain the calls::
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ds.Query.hero.select(ds.Character.name).select(ds.Character.id)
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Or do it sequencially::
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Or do it sequentially::
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hero_query = ds.Query.hero
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Multiple operations in a document
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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It is possible to create an Document with multiple operations::
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It is possible to create a Document with multiple operations::
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query = dsl_gql(
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operation_name_1=DSLQuery( ... ),
@@ -384,6 +384,305 @@ you can use the :class:`DSLMetaField <gql.dsl.DSLMetaField>` class::
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DSLMetaField("__typename")
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)
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Directives
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^^^^^^^^^^
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`Directives`_ provide a way to describe alternate runtime execution and type validation
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behavior in a GraphQL document. The DSL module supports both built-in GraphQL directives
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(:code:`@skip`, :code:`@include`) and custom schema-defined directives.
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To add directives to DSL elements, use the :meth:`DSLSchema.__call__ <gql.dsl.DSLSchema.__call__>`
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factory method and the :meth:`directives <gql.dsl.DSLDirectable.directives>` method::
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# Using built-in @skip directive with DSLSchema.__call__ factory
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ds.Query.hero.select(
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ds.Character.name.directives(ds("@skip").args(**{"if": True}))
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)
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Directive Arguments
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"""""""""""""""""""
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Directive arguments can be passed using the :meth:`args <gql.dsl.DSLDirective.args>` method.
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For arguments that don't conflict with Python reserved words, you can pass them directly::
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# Using the args method for non-reserved names
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ds("@custom").args(value="foo", reason="testing")
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It can also be done by calling the directive directly::
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ds("@custom")(value="foo", reason="testing")
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However, when the GraphQL directive argument name conflicts with a Python reserved word
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(like :code:`if`), you need to unpack a dictionary to escape it::
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# Dictionary unpacking for Python reserved words
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ds("@skip").args(**{"if": True})
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ds("@include")(**{"if": False})
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This ensures that the exact GraphQL argument name is passed to the directive and that
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no post-processing of arguments is required.
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The :meth:`DSLSchema.__call__ <gql.dsl.DSLSchema.__call__>` factory method automatically handles
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schema lookup and validation for both built-in directives (:code:`@skip`, :code:`@include`)
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and custom schema-defined directives using the same syntax.
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Directive Locations
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"""""""""""""""""""
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The DSL module supports all executable directive locations from the GraphQL specification:
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.. list-table::
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:header-rows: 1
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:widths: 25 35 40
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* - GraphQL Spec Location
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- DSL Class/Method
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- Description
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* - QUERY
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- :code:`DSLQuery.directives()`
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- Directives on query operations
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* - MUTATION
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- :code:`DSLMutation.directives()`
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- Directives on mutation operations
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* - SUBSCRIPTION
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- :code:`DSLSubscription.directives()`
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- Directives on subscription operations
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* - FIELD
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- :code:`DSLField.directives()`
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- Directives on fields (including meta-fields)
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* - FRAGMENT_DEFINITION
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- :code:`DSLFragment.directives()`
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- Directives on fragment definitions
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* - FRAGMENT_SPREAD
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- :code:`DSLFragmentSpread.directives()`
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- Directives on fragment spreads (via .spread())
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* - INLINE_FRAGMENT
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- :code:`DSLInlineFragment.directives()`
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- Directives on inline fragments
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* - VARIABLE_DEFINITION
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- :code:`DSLVariable.directives()`
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- Directives on variable definitions
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Examples by Location
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""""""""""""""""""""
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**Operation directives**::
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# Query operation
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query = DSLQuery(ds.Query.hero.select(ds.Character.name)).directives(
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ds("@customQueryDirective")
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)
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# Mutation operation
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mutation = DSLMutation(
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ds.Mutation.createReview.args(episode=6, review={"stars": 5}).select(
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ds.Review.stars
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)
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).directives(ds("@customMutationDirective"))
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**Field directives**::
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# Single directive on field
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ds.Query.hero.select(
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ds.Character.name.directives(ds("@customFieldDirective"))
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)
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# Multiple directives on a field
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ds.Query.hero.select(
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ds.Character.appearsIn.directives(
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ds("@repeat").args(value="first"),
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ds("@repeat").args(value="second"),
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ds("@repeat").args(value="third"),
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)
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)
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**Fragment directives**:
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You can add directives to fragment definitions and to fragment spread instances.
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To do this, first define your fragment in the usual way::
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name_and_appearances = (
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DSLFragment("NameAndAppearances")
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.on(ds.Character)
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.select(ds.Character.name, ds.Character.appearsIn)
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)
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Then, use :meth:`spread() <gql.dsl.DSLFragment.spread>` when you need to add
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directives to the fragment spread::
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query_with_fragment = DSLQuery(
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ds.Query.hero.select(
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name_and_appearances.spread().directives(
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ds("@customFragmentSpreadDirective")
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)
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)
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)
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The :meth:`spread() <gql.dsl.DSLFragment.spread>` method creates a
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:class:`DSLFragmentSpread <gql.dsl.DSLFragmentSpread>` instance that allows you to add
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directives specific to the fragment spread location, separate from directives on the
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fragment definition itself.
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Example with fragment definition and spread-specific directives::
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# Fragment definition with directive
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name_and_appearances = (
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DSLFragment("CharacterInfo")
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.on(ds.Character)
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.select(ds.Character.name, ds.Character.appearsIn)
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.directives(ds("@customFragmentDefinitionDirective"))
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)
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# Using fragment with spread-specific directives
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query_without_spread_directive = DSLQuery(
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# Direct usage (no spread directives)
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ds.Query.hero.select(name_and_appearances)
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)
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query_with_spread_directive = DSLQuery(
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# Enhanced usage with spread directives
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name_and_appearances.spread().directives(
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ds("@customFragmentSpreadDirective")
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)
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)
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# Don't forget to include the fragment definition in dsl_gql
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query = dsl_gql(
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name_and_appearances,
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BaseQuery=query_without_spread_directive,
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QueryWithDirective=query_with_spread_directive,
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)
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This generates GraphQL equivalent to::
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fragment CharacterInfo on Character @customFragmentDefinitionDirective {
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name
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appearsIn
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}
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{
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BaseQuery hero {
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...CharacterInfo
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}
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QueryWithDirective hero {
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...CharacterInfo @customFragmentSpreadDirective
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}
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}
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**Inline fragment directives**:
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Inline fragments also support directives using the
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:meth:`directives <gql.dsl.DSLInlineFragment.directives>` method::
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query_with_directive = ds.Query.hero.args(episode=6).select(
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ds.Character.name,
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DSLInlineFragment().on(ds.Human).select(ds.Human.homePlanet).directives(
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ds("@customInlineFragmentDirective")
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)
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)
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This generates::
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{
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hero(episode: JEDI) {
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name
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... on Human @customInlineFragmentDirective {
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homePlanet
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}
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}
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}
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**Variable definition directives**:
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You can also add directives to variable definitions using the
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:meth:`directives <gql.dsl.DSLVariable.directives>` method::
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var = DSLVariableDefinitions()
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var.episode.directives(ds("@customVariableDirective"))
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# Note: the directive is attached to the `.episode` variable definition (singular),
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# and not the `var` variable definitions (plural) holder.
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op = DSLQuery(ds.Query.hero.args(episode=var.episode).select(ds.Character.name))
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op.variable_definitions = var
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This will generate::
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query ($episode: Episode @customVariableDirective) {
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hero(episode: $episode) {
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name
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}
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}
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Complete Example for Directives
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"""""""""""""""""""""""""""""""
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Here's a comprehensive example showing directives on multiple locations:
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.. code-block:: python
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from gql.dsl import DSLFragment, DSLInlineFragment, DSLQuery, dsl_gql
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# Create variables for directive conditions
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var = DSLVariableDefinitions()
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# Fragment with directive on definition
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character_fragment = DSLFragment("CharacterInfo").on(ds.Character).select(
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ds.Character.name, ds.Character.appearsIn
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).directives(ds("@fragmentDefinition"))
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# Query with directives on multiple locations
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query = DSLQuery(
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ds.Query.hero.args(episode=var.episode).select(
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# Field with directive
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ds.Character.name.directives(ds("@skip").args(**{"if": var.skipName})),
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# Fragment spread with directive
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character_fragment.spread().directives(
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ds("@include").args(**{"if": var.includeFragment})
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),
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# Inline fragment with directive
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DSLInlineFragment().on(ds.Human).select(ds.Human.homePlanet).directives(
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ds("@skip").args(**{"if": var.skipHuman})
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),
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# Meta field with directive
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DSLMetaField("__typename").directives(
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ds("@include").args(**{"if": var.includeType})
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)
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)
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).directives(ds("@query")) # Operation directive
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# Variable definition with directive
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var.episode.directives(ds("@variableDefinition"))
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query.variable_definitions = var
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# Generate the document
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document = dsl_gql(character_fragment, query)
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This generates GraphQL equivalent to::
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fragment CharacterInfo on Character @fragmentDefinition {
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name
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appearsIn
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}
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query (
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$episode: Episode @variableDefinition
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$skipName: Boolean!
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$includeFragment: Boolean!
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$skipHuman: Boolean!
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$includeType: Boolean!
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) @query {
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hero(episode: $episode) {
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name @skip(if: $skipName)
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...CharacterInfo @include(if: $includeFragment)
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... on Human @skip(if: $skipHuman) {
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homePlanet
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}
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__typename @include(if: $includeType)
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}
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}
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Executable examples
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-------------------
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.. _Fragment: https://graphql.org/learn/queries/#fragments
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.. _Inline Fragment: https://graphql.org/learn/queries/#inline-fragments
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.. _Directives: https://graphql.org/learn/queries/#directives
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.. _issue #308: https://github.com/graphql-python/gql/issues/308

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