Graphene Django 中的 DjangoListField() 与 graphene.List()

Question

我使用“DjangoListField()”和“graphene.List()”与解析器来列出所有对象。

schema.py 中的“DjangoListField()”：

import graphene
from graphene_django import DjangoObjectType
from graphene_django import DjangoListField
from .models import Category

class CategoryType(DjangoObjectType):
    class Meta:
        model = Category
        fields = ("id","name")

class Query(graphene.ObjectType):

    all_categories = DjangoListField(CategoryType) # DjangoListField()

    def resolve_all_categories(root, info): # Resolver to list all objects
        return Category.objects.all()

schema = graphene.Schema(query=Query)

schema.py 中的“graphene.List()”：

import graphene
from graphene_django import DjangoObjectType
from .models import Category

class CategoryType(DjangoObjectType):
    class Meta:
        model = Category
        fields = ("id","name")

class Query(graphene.ObjectType):

    all_categories = graphene.List(CategoryType) # graphene.List()

    def resolve_all_categories(root, info): # Resolver to list all objects
        return Category.objects.all()

schema = graphene.Schema(query=Query)

然后，我在“allCategories”中一一查询了上面schema.py中的两段代码：

query {
  allCategories {
    id
    name
  }
}

但列出所有对象的结果是相同的：

{
  "data": {
    "allCategories": [
      {
        "id": "1",
        "name": "category1"
      },
      {
        "id": "2",
        "name": "category2"
      }
    ]
  }
}

“DjangoListField()”和“graphene.List()”有什么区别？

Answer 1

“DjangoListField()”具有默认解析器来列出所有对象，但“graphene.List()”没有它，因此对于“graphene.List()”，您需要显式定义解析器来列出所有对象，否则您会得到“无效的”。

因此，如果您使用“DjangoListField()”从代码中删除解析器：

import graphene
from graphene_django import DjangoObjectType
from graphene_django import DjangoListField
from .models import Category

class CategoryType(DjangoObjectType):
    class Meta:
        model = Category
        fields = ("id","name")

class Query(graphene.ObjectType):

    all_categories = DjangoListField(CategoryType) # DjangoListField()

schema = graphene.Schema(query=Query)

然后，您查询“allCategories”：

query {
  allCategories {
    id
    name
  }
}

最后，您仍然可以列出所有对象：

{
  "data": {
    "allCategories": [
      {
        "id": "1",
        "name": "category1"
      },
      {
        "id": "2",
        "name": "category2"
      }
    ]
  }
}

但是，如果您使用“graphene.List()”从代码中删除Resolver：

import graphene
from graphene_django import DjangoObjectType
from .models import Category

class CategoryType(DjangoObjectType):
    class Meta:
        model = Category
        fields = ("id","name")

class Query(graphene.ObjectType):

    all_categories = graphene.List(CategoryType) # graphene.List()

schema = graphene.Schema(query=Query)

然后，您查询“allCategories”：

query {
  allCategories {
    id
    name
  }
}

最后，您无法列出所有对象，而是得到“null”：

{
  "data": {
    "allCategories": null
  }
}

您可以在此页面DjangoListField中获得有关“DjangoListField()”的更多详细信息。