silverstripe-framework/docs/en/02_Developer_Guides/19_GraphQL/06_extending/adding_a_custom_operation.md

title	summary
Adding a custom operation	Add a new operation for model types

Extending the schema

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Adding a custom operation

By default, we get basic operations for our models, like read, create, update, and delete, but we can add to this list by creating an implementation of OperationProvider and registering it.

Let's build a new operation that duplicates DataObjects.

class DuplicateCreator implements OperationCreator
{
    public function createOperation(
        SchemaModelInterface $model,
        string $typeName,
        array $config = []
    ): ?ModelOperation
    {
        $mutationName = 'duplicate' . ucfirst(Schema::pluralise($typeName));

        return ModelMutation::create($model, $mutationName)
            ->setType($typeName)
            ->addArg('id', 'ID!')
            ->setDefaultResolver([static::class, 'resolve'])
            ->setResolverContext([
                'dataClass' => $model->getSourceClass(),
            ]);
    }

We add resolver context to the mutation because we need to know what class to duplicate, but we need to make sure we still have a static function.

The signature for resolvers with context is:

public static function (array $context): Closure;

We use the context to pass to a function that we'll create dynamically. Let's add that now.

public static function resolve(array $resolverContext = []): Closure
{
    $dataClass = $resolverContext['dataClass'] ?? null;
    return function ($obj, array $args) use ($dataClass) {
        if (!$dataClass) {
            return null;
        }
        return DataObject::get_by_id($dataClass, $args['id'])
        	->duplicate();
    };
}

Now, just add the operation to the DataObjectModel configuration to make it available to all DataObject types.

SilverStripe\GraphQL\Schema\DataObject\DataObjectModel:
  operations:
    duplicate: 'MyProject\Operations\DuplicateCreator'

And use it:

app/_graphql/models.yml

MyProject\Models\MyDataObject:
  fields: '*'
  operations:
    read: true
    duplicate: true

Further reading

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