com.apollographql.apollo.response

Interface CustomTypeAdapter<T>

public interface CustomTypeAdapter<T>

Class represents the adapter for mapping GraphQL custom scalar types to Java objects.

Defining a custom scalar type adapter

The GraphQL specification includes the following default scalar types: String, Int, Float and Boolean. But often use cases arise when support for custom scalar types is required and for those cases this class should be used to customize conversion. Here's an example of a type adapter for scalar type Date:

 CustomTypeAdapter<Date> dateCustomTypeAdapter = new CustomTypeAdapter<Date>() {

    public Date decode(CustomTypeValue value) {
      try {
        return ISO8601_DATE_FORMAT.parse(value);
      } catch (ParseException e) {
        throw new RuntimeException(e);
      }
    }

    public CustomTypeValue encode(Date value) {
      return ISO8601_DATE_FORMAT.format(value);
    }
 };
 
 

To use a custom type adapter with Apollo, you must first define the mapping in the build.gradle file:

 apollo {
  customTypeMapping['DateTime'] = "java.util.Date"
 }
 
 

The lines above tell the compiler which type to use while generating the classes. Once this is done, register the type adapter with ApolloClient.Builder:

 ApolloClient.Builder builder = ApolloClient.builder()
  .addCustomTypeAdapter(CustomType.DATE, dateCustomTypeAdapter);
 
 

In the example code above, the CustomType.DATE is the class generated by the compiler.

Method Summary

Modifier and Type	Method and Description
T	decode(CustomTypeValue value) De-serializes the value to the custom scalar type.
CustomTypeValue	encode(T value) Serializes the custom scalar type to the corresponding string value.

Method Detail

decode

T decode(@NotNull
         CustomTypeValue value)

De-serializes the value to the custom scalar type. Usually used in parsing the GraphQL response.

Parameters:

value - the value to de-serialize

Returns:

custom scalar type

encode

@NotNull
CustomTypeValue encode(@NotNull
                                T value)

Serializes the custom scalar type to the corresponding string value. Usually used in serializing variables or input values.

Parameters:

value - the custom scalar type to serialize

Returns:

serialized string value