graphene-django-cud 0.0.6

Create, update and delete mutations for graphene-django

Graphene Django CUD

This package contains a number of helper mutations making it easy to construct create, update and delete mutations for django models.

The helper mutations are:

• DjangoCreateMutation
• DjangoPatchMutation
• DjangoUpdateMutation
• DjangoDeleteMutation
• DjangoBatchDeleteMutation

The package handles both regular ids and relay ids automatically.

Basic usage

To use, here illustrated by DjangoCreateMutation, simply create a new inherting class. Suppose we have the following model and Node.

class User(models.Model):
    name = models.CharField(max_length=255)
    address = models.TextField()

class UserNode(DjangoObjectType):
    class Meta:
        model = User
        interfaces = (Node,)

Then we can create a create mutation with the following schema

class CreateUserMutation(DjangoCreateMutation):
    class Meta:
        model = User


class Mutation(graphene.ObjectType):
    create_user = CreateUserMutation.Field()


schema = Schema(mutation=Mutation)

Note that the UserNode has to be registered as a field before the mutation is instantiated. This will be configurable in the future.

The input to the mutation is a single variable input which is automatically created with the models fields. An example mutation would then be

mutation {
    createUser(input: {name: "John Doe", address: "Downing Street 10"}){
        user{
            id
            name
            address
        } 
    }
}

Mutations

DjangoCreateMutation

Will create a new mutation which will create a new object of the supplied model.

Mutation input arguments:

Argument	Type
input	Object!

Meta fields:

Field	Type	Default	Description
model	Model	None	The model. Required.
only_fields	Iterable	None	If supplied, only these fields will be added as input variables for the model
exclude_fields	Iterable	None	If supplied, these fields will be excluded as input variables for the model.
return_field_name	String	None	The name of the return field within the mutation. The default is the camelCased name of the model
permissions	Tuple	None	The permissions required to access the mutation
login_required	Boolean	None	If true, the calling user has to be authenticated
auto_context_fields	Dict	None	A mapping of context values into model fields. See below
optional_fields	Tuple	()	A list of fields which explicitly should have required=False
required_fields	Tuple	None	A list of fields which explicitly should have required=True
type_name	String	None	If supplied, the input variable in the mutation will have its typename set to this string. This is useful when creating multiple mutations of the same type for a single model.
many_to_many_extras	Dict	{}	A dict with extra information regarding many-to-many fields. See below.
many_to_one_extras	Dict	{}	A dict with extra information regarding many-to-one relations. See below.
foreign_key_extras	Dict	{}	A dict with extra information regarding foreign key extras.

Example mutation

mutation {
    createUser(input: {name: "John Doe", address: "Downing Street 10"}){
        user{
            id
            name
            address
        } 
    }
}

DjangoUpdateMutation

Will update an existing instance of a model. The UpdateMutation (in contrast to the PatchMutation) requires all fields to be supplied by default.

Mutation input arguments:

Argument	Type
id	ID!
input	Object!

All meta arguments:

Argument	type	Default	Description
model	Model	None	The model. Required.
only_fields	Iterable	None	If supplied, only these fields will be added as input variables for the model
exclude_fields	Iterable	None	If supplied, these fields will be excluded as input variables for the model.
return_field_name	String	None	The name of the return field within the mutation. The default is the camelCased name of the model
permissions	Tuple	None	The permissions required to access the mutation
login_required	Boolean	None	If true, the calling user has to be authenticated
auto_context_fields	Dict	None	A mapping of context values into model fields. See below
optional_fields	Tuple	()	A list of fields which explicitly should have required=False
required_fields	Tuple	None	A list of fields which explicitly should have required=True
type_name	String	None	If supplied, the input variable in the mutation will have its typename set to this string. This is useful when creating multiple mutations of the same type for a single model.
many_to_many_extras	Dict	{}	A dict with extra information regarding many-to-many fields. See below.
many_to_one_extras	Dict	{}	A dict with extra information regarding many-to-one relations. See below.
foreign_key_extras	Dict	{}	A dict with extra information regarding foreign key extras.

Example mutation

mutation {
    updateUser(id: "VXNlck5vZGU6MQ==", input: {
        name: "John Doe", 
        address: "Downing Street 10"
    }){
        user{
            id
            name
            address
        } 
    }
}

DjangoPatchMutation

Will update an existing instance of a model. The PatchMutation (in contrast to the UpdateMutation) does not require all fields to be supplied. I.e. all are fields are optional.

Mutation input arguments:

Argument	Type
id	ID!
input	Object!

All meta arguments:

Argument	type	Default	Description
model	Model	None	The model. Required.
only_fields	Iterable	None	If supplied, only these fields will be added as input variables for the model
exclude_fields	Iterable	None	If supplied, these fields will be excluded as input variables for the model.
return_field_name	String	None	The name of the return field within the mutation. The default is the camelCased name of the model
permissions	Tuple	None	The permissions required to access the mutation
login_required	Boolean	None	If true, the calling user has to be authenticated
auto_context_fields	Dict	None	A mapping of context values into model fields. See below
optional_fields	Tuple	()	A list of fields which explicitly should have required=False
required_fields	Tuple	None	A list of fields which explicitly should have required=True
type_name	String	None	If supplied, the input variable in the mutation will have its typename set to this string. This is useful when creating multiple mutations of the same type for a single model.
many_to_many_extras	Dict	{}	A dict with extra information regarding many-to-many fields. See below.
many_to_one_extras	Dict	{}	A dict with extra information regarding many-to-one relations. See below.
foreign_key_extras	Dict	{}	A dict with extra information regarding foreign key extras.

Example mutation

mutation {
    updateUser(id: "VXNlck5vZGU6MQ==", input: {
        name: "John Doe", 
    }){
        user{
            id
            name
            address
        } 
    }
}

DjangoDeleteMutation

Will delete an existing instance of a model. The returned arguments are:

• found: True if the instance was found and deleted.
• deletedId: THe id of the deleted instance.

Mutation input arguments:

Argument	Type
id	ID!

All meta arguments:

Argument	type	Default	Description
model	Model	None	The model. Required.
permissions	Tuple	None	The permissions required to access the mutation
login_required	Boolean	None	If true, the calling user has to be authenticated

Example mutation

mutation {
    deleteUser(id: "VXNlck5vZGU6MQ=="){
        found
        deletedId
    }
}

DjangoBatchDeleteMutation

Will delete multiple instances of a model depending on supplied filters. The returned arguments are:

• deletionCount: True if the instance was found and deleted.
• deletedIds: The ids of the deleted instances.

Mutation input arguments:

Argument	Type
input	Object!

All meta arguments:

Argument	type	Default	Description
model	Model	None	The model. Required.
filter_fields	Tuple	()	A number of filter fields which allow us to restrict the instances to be deleted.
permissions	Tuple	None	The permissions required to access the mutation
login_required	Boolean	None	If true, the calling user has to be authenticated

If there are multiple filters, these will be combined with and-clauses. For or-clauses, use multiple mutation calls.

Example

Class, with an assumed foreign key to a House model:

class BatchDeleteUser(DjangoBatchDeleteMutation):
    class Meta:
        model = User
        filter_fields = ('name', 'house__address',)

Mutation:

mutation {
    batchDeleteUser(input: {name: 'John'}){
        deletedIds
        deletionCount
    }
}

Auto context fields

The create, update and patch mutations contains a meta-field auto_context_fields. It allows us to automatically assign field values depending on values in the context (i.e. the current HttpRequest). Most typically, this will be used to automatically assign the the current user to some field.

Suppose for instance you have the following model:

class ForumThread(models.Model):
    created_by = models.ForeignKey(User, on_delete=models.CASCADE)

    # More fields

We can then automatically assign the created_by field to the calling user by creating a mutation:

class CreateForumThreadMutation(DjangoCreateMutation):
    class Meta:
        auto_context_fields = {
            'created_by': 'user' 
        }

Presupposing, of course, that the user field of the info.context (HttpRequest) field is set. This works with any context field. Also note that auto context fields are automatically set as required=False, to please Graphene. Finally note that if we add an explicit value to the createdBy field when calling the mutation, this value will override the auto context field.

Extras and nested mutations

There are three meta fields which allow us to extend the handling of both sides of a foreign key relationship (foreign key extras and many to one extras), as well as many to many relationships.

Foreign key extras

The foreign_key_extras field is a dictionary containing information regarding how to handle a model's foreign keys. Here is an example:

class Cat(models.Model):
    owner = models.ForeignKey(User, on_delete=models.CASCADE)
    name = models.TextField(

class CreateCatMutation(DjangoCreateMutation):
    class Meta:
        model = Cat
        foreign_key_extras = {"owner": {"type": "CreateUserInput"}}

By default, the owner field is of type ID!, i.e. you have to supply the ID of an owner when creating a cat. But suppose you instead for every cat want to create a new user as well. Well that's exactly what this mutation allows for (demands).

Here, the owner field will now be of type CreateUserInput!, which has to have been created before, typically via a CreateUserMutation, which by default will result in the type name CreateUserInput. An example call to the mutation is:

mutation {
    createCat(input: {owner: {name: "John Doe"}, name: "Kitty"}){
        cat{
            name
            owner {
                id
                name
            } 
        }
    }
}

A current TODO here is to allow the type to be auto, which will automatically create a new type. This is useful in cases where you don't want to reuse an existing type.

Many to one extras

The many_to_one_extras field is a dictionary containing information regarding how to handle many to one relations, i.e. the "other" side of a foreign key. Suppose we have the Cat model as above. Looking from the User-side, we could add nested creations of Cat's, by the following mutation

class CreateUserMutation(DjangoCreateMutation):
    class Meta:
        model = User
        many_to_one_extras = {
            "cats": {
                "add": {"type": "auto"}
            }
        }

This will add an input argument catsAdd, which accepts an array of Cat objects. Note that the type value auto means that a new type to accept the cat object will be created. This is usually necessary, as the regular CreateCatInput requires an owner id, which we do not want to give here, as it is inferred.

Now we could create a user with multiple cats in one go as follows:

mutation {
    createUser(input: {
        name: "User",
        catsAdd: [
            {name: "First Kitty"},
            {name: "Second kitty"}
        ] 
    }){
        user{
            id
            name
            cats{
                edges{
                    node{
                        id
                    } 
                }
            }
        }
    }
}

Note that the default many to one relation argument cats still accepts a list of inputs. You might want to keep it this way. However, you can override the default by adding an entry with the key "exact":

class CreateUserMutation(DjangoCreateMutation):
    class Meta:
        model = User
        many_to_one_extras = {
            "cats": {
                "exact": {"type": "auto"}
            }
        }

Note that we can add a new key with the type "ID", to still allow for Cat objects to be added by id.

class CreateUserMutation(DjangoCreateMutation):
    class Meta:
        model = User
        many_to_one_extras = {
            "cats": {
                "exact": {"type": "auto"},
                "by_id": {"type": "ID"}
            }
        }


mutation {
    createUser(input: {
        name: "User",
        cats: [
            {name: "First Kitty"},
            {name: "Second kitty"}
        ],
        catsById: ["Q2F0Tm9kZTox"]
    }){
        user{
            ...UserInfo
        }
    }
}

Many to many extras

The many_to_one_extras field is a dictionary containing information regarding how to handle many to many relations. Suppose we have the Cat model as above, and a Dog model like:

class Dog(models.Model):
    owner = models.ForeignKey(User, null=True, on_delete=models.SET_NULL)
    name = models.TextField()

    enemies = models.ManyToManyField(Cat, blank=True, related_name='enemies')

    def is_stray():
        return self.owner is None


class DogNode(DjangoObjectType):
    class Meta:
        model = Dog

We now have a many to many relationship, which by default will be modelled by default using an [ID] argument. However, this can be customized fairly similar to many to one extras:

class CreateDogMutation(DjangoCreateMutation):
    class Meta:
        model = Dog
        many_to_many_extras = {
            'enemies': {
                'add': {"type": "CreateCatInput"} 
            } 
        }

This will, similar to before, add an enemiesAdd argument:

mutation {
    createDog(input: {
        name: "Buster", 
        enemies: ["Q2F0Tm9kZTox"], 
        enemiesAdd: [{owner: "VXNlck5vZGU6MQ==", name: "John's cat"]
    }}){
        dog{
            ...DogInfo 
        } 
    }
}

This will create a dog with two enemies, one that already exists, and a new one, which has the owner VXNlck5vZGU6MQ== (some existing user). Note that if CreateCatInput expects us to create a new user, we would have to do that here.

We can also add an extra field here for removing entities from a many to many relationship:

class UpdateDogMutation(DjangoUpdateMutation):
    class Meta:
        model = Dog
        many_to_many_extras = {
            "enemies": {
                "add": {"type": "CreateCatInput"},
                "remove": {"type": "ID"},
                # A similar form would be "remove": true
            } 
        }

Note that this has to have the type "ID". Also note that this has no effect on DjangoCreateMutation mutations. We could then perform

mutation {
    updateDog(id: "RG9nTm9kZTox", input: {
        name: "Buster 2", 
        enemiesRemove: ["Q2F0Tm9kZTox"],
        enemiesAdd: [{owner: "VXNlck5vZGU6MQ==", name: "John's cat"]
    }}){
        dog{
            ...DogInfo 
        } 
    }
}

This would remove "Q2F0Tm9kZTox" as an enemy, but create a new one as before.

We can alter the behaviour of the default argument (e.g. enemies), by adding the "exact":

class UpdateDogMutation(DjangoUpdateMutation):
    class Meta:
        model = Dog
        many_to_many_extras = {
            "enemies": {
                "exact": {"type": "CreateCatInput"},
                "remove": {"type": "ID"},
                # A similar form would be "remove": true
            } 
        }

mutation {
    updateDog(id: "RG9nTm9kZTox", input: {
        name: "Buster 2", 
        enemiesRemove: ["Q2F0Tm9kZTox"],
        enemiesAdd: [{owner: "VXNlck5vZGU6MQ==", name: "John's cat"]
    }}){
        dog{
            ...DogInfo 
        } 
    }
}

This will have the rather odd behavior that all enemies are reset, and only the new ones created will be added to the relationship. In other words it exists as a sort of purge and create functionality. When used in a DjangoCreateMutation it will simply function as an initial populator of the relationship.

A TODO here is adding the type auto for many to many extras.

Other aliases

In both the many to many and many to one extras cases, the naming of the extra fields are not arbitrary. However, they can be customized; with effect in particular for many to many extras. Suppose you want your field to be named enemiesKill, which should remove from a many to many relationship. Then initially, we might write:

class UpdateDogMutation(DjangoUpdateMutation):
    class Meta:
        model = Dog
        many_to_many_extras = {
            "enemies": {
                "exact": {"type": "CreateCatInput"},
                "kill": {"type": "ID"},
            } 
        }

Unfortunately, this will not work, as graphene-django-cud does not know what operation kill translates to? Should we add or remove (or set) the entities? Fortunately, we explicit tell which operation to use, by supplying the "operation" key:

class UpdateDogMutation(DjangoUpdateMutation):
    class Meta:
        model = Dog
        many_to_many_extras = {
            "enemies": {
                "exact": {"type": "CreateCatInput"},
                "kill": {"type": "ID", "operation": "remove"},
            } 
        }

Legal values are "add", "remove", and "update" (and some aliases of these).

If you want even more flexible fields, you can also explicitly set the name:

class UpdateDogMutation(DjangoUpdateMutation):
    class Meta:
        model = Dog
        many_to_many_extras = {
            "enemies": {
                "exact": {"type": "CreateCatInput"},
                "additional": {"type": "ID", "operation": "remove", "name": "additional_enemies"},
            } 
        }

Note that the name will be translated from snake_case to camelCase as per usual. Had we not added the name here, it would have defaulted to "enemiesAdditional", instead of "additionalEnemies".

Deep nested arguments

Note that deeply nested arguments are added by default when using existing types. Hence, for the mutation

class CreateDogMutation(DjangoCreateMutation):
    class Meta:
        model = Dog
        many_to_many_extras = {
            "enemies": {
                "exact": {"type": "CreateCatInput"},
            } 
        }

Where CreateCatInput is the type generated for

class CreateCatMutation(DjangoCreateMutation):
    class Meta:
        model = Cat
        many_to_many_extras = {
            "targets": {"exact": {"type": "CreateMouseInput"}},
        }
        foreign_key_extras = {"owner": {"type": "CreateUserInput"}}

Where we assume we have now also created a new model Mouse with a standard CreateMouseMutation mutation. We could then execute with success the following massive mutation:

mutation {
    createDog(input: {
        owner: null, 
        name: "Spark",
        enemies: [
            {
                name: "Kitty", 
                owner: {name: "John doe"}, 
                targets: [
                    {name: "Mickey mouse"}
                ]
            },
            {
                name: "Kitty",
                owner: {name: "Ola Nordmann"}
            }
        ]
   }){
        ...DogInfo
   }
}

This creates a new (stray) dog, two new cats with one new owner each and one new mouse. The new cats and the new dog are automatically set as enemies, and the mouse is automatically set as a target of the first cat.

Handle functions

TODO

Validate functions

TODO

get_ functions

TODO

Examples

TODO

Limitations and known issues

One could wish for an API where you could specify both IDs and objects in a single array for many to many and many to one relations. However, due to GraphQLs strict type system, this is not currently possible — in particular due to the fact that scalars and object types cannot be together in a union.

Some workarounds could be implemented for this, but we deem this more dirty than useful.