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Resolver

The most common way to assign a specific resolver to a field is to decorate your resolver callable with the @Resolver decorator. Your function MUST BE compliant with the function signature and be async.

from tartiflette import Resolver


@Resolver("Query.hello")
async def my_hello_resolver(parent, args, context, info):
    return "Chuck"

Function signature

Every resolver in Tartiflette accepts four positional arguments:

(This signature is highly inspired by the GraphQL.js implementation)

async def my_hello_resolver(
    parent: Optional[Any],
    args: Dict[str, Any],
    ctx: Optional[Any],
    info: "ResolveInfo",
) -> Any:
    pass

• parent (Optional[Any]): resolved value returned by the parent resolver field, if the parent is a root type (Query/Mutation/Subscription) the value passed will be the initial_value of the execution
• args (Dict[str, Any]): a dictionary containing the arguments passed for the field. (in the query). e.g. if the field was called with hello(name: "Chuck"), the args dictionary will be equals to {"name": "Chuck"}
• ctx (Optional[Any]): will be the value of the context argument provided when calling the execute or subscribe's Engine method
• info ("ResolveInfo"): internal Tartiflette object containing information related to the execution and the resolved field. It CAN BE used for advanced use-cases (more detail here)

Resolver info argument

The info argument contains information related to the execution and the resolved field which can be useful for middlewares and advanced use-cases.

Here are the available properties:

• field_name (str): name of the resolved field
• field_nodes (List["FieldNodes"]): AST nodes related to the resolved field
• return_type ("GraphQLOutputType"): GraphQLOutputType instance of the resolved field
• parent_type ("GraphQLObjectType"): GraphQLObjectType of the field's parent
• path ("Path"): the path traveled until this field
• schema ("GraphQLSchema"): the GraphQLSchema instance linked to resolved field
• fragments (Dict[str, "FragmentDefinitionNode"]): a dictionary of fragment definition AST nodes contained in the request
• root_value (Optional[Any]): the initial value corresponding to provided value at execute or subscribe method call
• operation ("OperationDefinitionNode"): the AST operation definition node to execute
• variable_values (Optional[Dict[str, Any]]): the variables provided in the GraphQL request
• is_introspection (bool): determines whether or not the resolved field is in a context of an introspection query