Source code for graphene.types.structures
from .unmountedtype import UnmountedType
from .utils import get_type
class Structure(UnmountedType):
"""
A structure is a GraphQL type instance that
wraps a main type with certain structure.
"""
def __init__(self, of_type, *args, **kwargs):
super(Structure, self).__init__(*args, **kwargs)
if not isinstance(of_type, Structure) and isinstance(of_type, UnmountedType):
cls_name = type(self).__name__
of_type_name = type(of_type).__name__
raise Exception(
f"{cls_name} could not have a mounted {of_type_name}()"
f" as inner type. Try with {cls_name}({of_type_name})."
)
self._of_type = of_type
@property
def of_type(self):
return get_type(self._of_type)
def get_type(self):
"""
This function is called when the unmounted type (List or NonNull instance)
is mounted (as a Field, InputField or Argument)
"""
return self
[docs]class List(Structure):
"""
List Modifier
A list is a kind of type marker, a wrapping type which points to another
type. Lists are often created within the context of defining the fields of
an object type.
List indicates that many values will be returned (or input) for this field.
.. code:: python
from graphene import List, String
field_name = List(String, description="There will be many values")
"""
def __str__(self):
return f"[{self.of_type}]"
def __eq__(self, other):
return isinstance(other, List) and (
self.of_type == other.of_type
and self.args == other.args
and self.kwargs == other.kwargs
)
[docs]class NonNull(Structure):
"""
Non-Null Modifier
A non-null is a kind of type marker, a wrapping type which points to another
type. Non-null types enforce that their values are never null and can ensure
an error is raised if this ever occurs during a request. It is useful for
fields which you can make a strong guarantee on non-nullability, for example
usually the id field of a database row will never be null.
Note: the enforcement of non-nullability occurs within the executor.
NonNull can also be indicated on all Mounted types with the keyword argument ``required``.
.. code:: python
from graphene import NonNull, String
field_name = NonNull(String, description='This field will not be null')
another_field = String(required=True, description='This is equivalent to the above')
"""
def __init__(self, *args, **kwargs):
super(NonNull, self).__init__(*args, **kwargs)
assert not isinstance(
self._of_type, NonNull
), f"Can only create NonNull of a Nullable GraphQLType but got: {self._of_type}."
def __str__(self):
return f"{self.of_type}!"
def __eq__(self, other):
return isinstance(other, NonNull) and (
self.of_type == other.of_type
and self.args == other.args
and self.kwargs == other.kwargs
)