Pagination 在graphene relay.ConnectionField中强制分页

graphene附带的

relay.ConnectionField

实现默认情况下不会对查询进行分页。（可以选择使用“first”或“last”对连接进行分页。）如果连接具有大量节点，则这是不实际的。强制分页（例如一次不超过100个节点）的适当方式是什么

不幸的是，石墨烯不支持默认值。我为这种箱子做了一个装饰工。适当设置

默认页面大小

和

最大页面大小

。可以进行调整以从装饰器本身接收这些值，但我将其与Django和ergo Django的设置一起使用

DEFAULT_PAGE_SIZE = 10
MAX_PAGE_SIZE = 100

def limited_pagination(func):
    '''
    Decorator for limiting the `first` and `last` pagination parameters. Uses
    DEFAULT_PAGE_SIZE and MAX_PAGE_SIZE settings. Raises an exception when
    values are invalid.
    '''

    def wrapper(*args, **kwargs):
        if 'first' in kwargs and 'last' in kwargs:
            raise RuntimeError('Use either `first` or `last`, not both.')

        for key in ('first', 'last'):
            if key in kwargs:
                try:
                    value = int(kwargs[key])
                except ValueError:
                    raise ValueError('`{}` must be an integer.'.format(key))

                if value < 0:
                    raise ValueError('`{}` must be 0 or greater.'.format(key))
                elif value > MAX_PAGE_SIZE:
                    raise ValueError(
                        '`{}` must not be greater than {}.'.format(
                            key, MAX_PAGE_SIZE
                        )
                    )

                kwargs[key] = value
                break # Break out of for loop to skip `else` branch.

        else:
            kwargs['first'] = DEFAULT_PAGE_SIZE

        result = func(*args, **kwargs)
        return result

    return wrapper

---

对于那些寻找django解决方案的人，graphene django具有

中继连接\u强制执行\u FIRST\u或\u LAST

和

中继连接\u MAX\u LIMIT

设置：。您只需启用

RELAY\u CONNECTION\u efforce\u FIRST\u或\u LAST

，并确保在查询声明中使用

djangconnectionfield

例如：

# settings
GRAPHENE = {
    'RELAY_CONNECTION_ENFORCE_FIRST_OR_LAST': True,
    'RELAY_CONNECTION_MAX_LIMIT': 50,
}

# model
class Category(models.Model):
    name = models.CharField(max_length=100)

# graphql type
class CategoryType(graphene_django.DjangoObjectType):
    class Meta:
        model = Category
        fields = ("id", 'name')
        interfaces = (graphene.relay.Node,)

# query
class Query(graphene.ObjectType):
    categories = graphene_django.DjangoConnectionField(CategoryType)

    def resolve_categories(root, info, **kwargs):
        return Category.objects.all().order_by("id")

---

什么意思？你想问下两个问题吗？谢谢。对于像SQLAlchemy连接这样的连接，您有什么建议吗？通常，您根本不需要为连接/外键定义resolve_*函数，事实上这样做相当麻烦。

# settings
GRAPHENE = {
    'RELAY_CONNECTION_ENFORCE_FIRST_OR_LAST': True,
    'RELAY_CONNECTION_MAX_LIMIT': 50,
}

# model
class Category(models.Model):
    name = models.CharField(max_length=100)

# graphql type
class CategoryType(graphene_django.DjangoObjectType):
    class Meta:
        model = Category
        fields = ("id", 'name')
        interfaces = (graphene.relay.Node,)

# query
class Query(graphene.ObjectType):
    categories = graphene_django.DjangoConnectionField(CategoryType)

    def resolve_categories(root, info, **kwargs):
        return Category.objects.all().order_by("id")