Tools

Strawberry provides some utility functions to help you build your GraphQL server. All tools can be imported from strawberry.tools

create_type

Create a Strawberry type from a list of fields.

def create_type(name: str, fields: List[StrawberryField]) -> Type:
    ...

Example:

import strawberry
from strawberry.tools import create_type

@strawberry.field
def hello(info) -> str:
    return "World"

def get_name(info) -> str:
    return info.context.user.name
 
my_name = strawberry.field(name="myName", resolver=get_name)

Query = create_type("Query", [hello, my_name])

schema = strawberry.Schema(query=Query)

type Query {
  hello: String!
  myName: String!
}

merge_types

Merge multiple Strawberry types into one. Example:

import strawberry
from strawberry.tools import merge_types


@strawberry.type
class QueryA:
    @strawberry.field
    def perform_a(self) -> str:
        ...


@strawberry.type
class QueryB:
    @strawberry.field
    def perform_b(self) -> str:
        ...


ComboQuery = merge_types("ComboQuery", (QueryB, QueryA))
schema = strawberry.Schema(query=ComboQuery)

type ComboQuery {
  performB: String!
  performA: String!
}

QueryDepthLimiter

Extension to add a query depth limter validation rule that limits the complexity of queries by their depth to protect against malicious queries.

class QueryDepthLimiter(
    max_depth: int,
    ignore: Optional[List[Union[str, re.Pattern, Callable[[str], bool]]]] = None,
    callback: Optional[Callable[Dict[str, int]]] = None
):
    ...

Example:

import strawberry
from strawberry.extensions import QueryDepthLimiter

# assuming you already have a Query type
schema = strawberry.Schema(
  Query,
  extensions=[
    # Add the depth limiter extension
    QueryDepthLimiter(max_depth=3),
  ]
)

result = schema.execute_sync(
    """
    query MyQuery {
      user {
        pets {
          owner {
            pets {
              name
            }
          }
        }
      }
    }
    """
  )
)
assert len(result.errors) == 1
assert result.errors[0].message == "'MyQuery' exceeds maximum operation depth of 3"