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Closes gh-202
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Rossen Stoyanchev
2021-12-01 18:39:17 +00:00
parent 85cdadc2c8
commit 5597f543bd
4 changed files with 71 additions and 59 deletions
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88
spring-graphql-docs/src/docs/asciidoc/index.adoc
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@@ -671,6 +671,10 @@ Schema mapping handler methods can have any of the following method arguments:
| For access to field arguments with conversion.
See <<controllers-schema-mapping-argument>>.
| `@ProjectedPayload` Interface
| For access to field arguments through a project interface.
See <<controllers-schema-mapping-projectedpayload-argument>>.
| Source
| For access to the source (i.e. parent/container) instance of the field.
See <<controllers-schema-mapping-source>>.
@@ -740,50 +744,23 @@ You can use `@Argument` on a `Map<String, Object>` argument, to obtain all argum
values. The name attribute on `@Argument` must not be set.
[[controllers-schema-mapping-source]]
==== Source
[[controllers-schema-mapping-projectedpayload-argument]]
==== `@ProjectPayload` Interface
In GraphQL Java, the `DataFetchingEnvironment` provides access to the source (i.e.
parent/container) instance of the field. To access this, simply declare a method parameter
of the expected target type.
[source,java,indent=0,subs="verbatim,quotes"]
----
@Controller
public class BookController {
@SchemaMapping
public Author author(Book book) {
// ...
}
}
----
The source method argument also helps to determine the type name for the mapping.
If the simple name of the Java class matches the GraphQL type, then there is no need to
explicitly specify the type name in the `@SchemaMapping` annotation.
[TIP]
====
A <<controllers-batch-mapping>> handler method can batch load all authors for a query,
given a list of source/parent books objects.
====
[[controllers-schema-mapping-argument-projections]]
==== Argument Projections
When accessing individual arguments from a GraphQL request, interface projections can
be useful to access arguments through a well-defined interface.
Spring Data's `@ProjectedPayload` can be used to annotate projection interfaces that
can be declared as handler method arguments. Payload projection can work on top-level
arguments (`DataFetchingEnvironment.getArguments()`). Alternatively, projections can
be applied on individual arguments by using `@Argument` with a projected payload interface.
Argument projections are provided by https://docs.spring.io/spring-data/commons/docs/current/reference/html/#projections.interfaces[Spring Data's Interface projections]
As an alternative to using complete Objects with <<controllers-schema-mapping-argument>>,
you can also use a projection interface to access GraphQL request arguments through a
well-defined, minimal interface. Argument projections are provided by
https://docs.spring.io/spring-data/commons/docs/current/reference/html/#projections.interfaces[Spring Data's Interface projections]
when Spring Data is on the class path.
To make use of this, create an interface annotated with `@ProjectedPayload` and declare
it as a controller method parameter. If the parameter is annotated with `@Argument`,
it applies to an individual argument within the `DataFetchingEnvironment.getArguments()`
map. When declared without `@Argument`, the projection works on top-level arguments in
the complete arguments map.
For example:
[source,java,indent=0,subs="verbatim,quotes"]
----
@Controller
@@ -817,6 +794,35 @@ when Spring Data is on the class path.
----
[[controllers-schema-mapping-source]]
==== Source
In GraphQL Java, the `DataFetchingEnvironment` provides access to the source (i.e.
parent/container) instance of the field. To access this, simply declare a method parameter
of the expected target type.
[source,java,indent=0,subs="verbatim,quotes"]
----
@Controller
public class BookController {
@SchemaMapping
public Author author(Book book) {
// ...
}
}
----
The source method argument also helps to determine the type name for the mapping.
If the simple name of the Java class matches the GraphQL type, then there is no need to
explicitly specify the type name in the `@SchemaMapping` annotation.
[TIP]
====
A <<controllers-batch-mapping>> handler method can batch load all authors for a query,
given a list of source/parent books objects.
====
[[controllers-schema-mapping-data-loader]]
==== `DataLoader`