Queries

In GraphQL you use queries to fetch data from a server. In Strawberry you can define the data your server provides by defining query types.

By default all the fields the API exposes are nested under a root Query type.

This is how you define a root query type in Strawberry:

@strawberry.type
class Query:
    name: str
 
 
schema = strawberry.Schema(query=Query)

This creates a schema where the root type Query has one single field called name.

As you notice we don't provide a way to fetch data. In order to do so we need to provide a resolver , a function that knows how to fetch data for a specific field.

For example in this case we could have a function that always returns the same name:

def get_name() -> str:
    return "Strawberry"
 
 
@strawberry.type
class Query:
    name: str = strawberry.field(resolver=get_name)
 
 
schema = strawberry.Schema(query=Query)

So now, when requesting the name field, the get_name function will be called.

Alternatively a field can be declared using a decorator:

@strawberry.type
class Query:
    @strawberry.field
    def name(self) -> str:
        return "Strawberry"

The decorator syntax supports specifying a graphql_type for cases when the return type of the function does not match the GraphQL type:

class User:
    id: str
    name: str
 
    def __init__(self, id: str, name: str):
        self.id = id
        self.name = name
 
@strawberry.type(name="User")
class UserType:
    id: strawberry.ID
    name: str
 
@strawberry.type
class Query:
    @strawberry.field(graphql_type=UserType)
    def user(self) -> User
        return User(id="ringo", name="Ringo")

Arguments

GraphQL fields can accept arguments, usually to filter out or retrieve specific objects:

FRUITS = [
    "Strawberry",
    "Apple",
    "Orange",
]
 
 
@strawberry.type
class Query:
    @strawberry.field
    def fruit(self, startswith: str) -> str | None:
        for fruit in FRUITS:
            if fruit.startswith(startswith):
                return fruit
        return None