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我已经编写了一些 graphql 模式并使用 prisma 部署它。Prisma 生成了一些.graphql文件type Query，type Mutation ,type Subscription。有一个从 docker 运行的 prisma 服务器正在连接 MySQL 数据库。现在我想使用 Ariadne 编写一些 API 函数并使用 Prisma 查询联系数据库。我怎样才能做到这一点？

提供给 prisma 的 GraphQL Schema

datamodel.prisma

type User {
  id: ID! @id 
  name: String!
}

生成的 graphql 文件示例

prisma.graphql

type Query {
  user(where: UserWhereUniqueInput!): User
  users(where: UserWhereInput, orderBy: UserOrderByInput, skip: Int, after: String, before: String, first: Int, last: Int): [User]!
  usersConnection(where: UserWhereInput, orderBy: UserOrderByInput, skip: Int, after: String, before: String, first: Int, last: Int): UserConnection!
  node(id: ID!): Node
}

使用 ariadne 尝试连接到数据库的 API 代码片段

我正在尝试执行users查询，即从数据库中获取所有用户。

api.py

from ariadne import gql, load_schema_from_path, QueryType, make_executable_schema
from ariadne.asgi import GraphQL

schema_files_path = "/root/manisha/prisma/generated/prisma.graphql"
schema = load_schema_from_path(schema_files_path)

query = QueryType()

@query.field("users")
def resolve_users(_, info):
    ...


schema = make_executable_schema(schema, query)
app = GraphQL(schema, debug=True)

使用 uvicorn 运行服务器 uvicorn api:app --reload --port 7000

我可以使用以下查询在 prisma playground 中获得所有用户。

{
  users{
    name
    id

  }
}

用于从数据库中获取所有用户的 prisma playground 的屏幕截图

用 ariadne 做同样的尝试resolve_users解析器尝试同样的方法是行不通的。

给我以下错误：

ERROR: Expected Iterable, but did not find one for field Query.users.

GraphQL request (2:3)
1: {
2:   users {
     ^ 
3:     id
Traceback (most recent call last):
  File "/usr/local/lib/python3.6/dist-packages/graphql/execution/execute.py", line 675, in complete_value_catching_error
    return_type, field_nodes, info, path, result
  File "/usr/local/lib/python3.6/dist-packages/graphql/execution/execute.py", line 750, in complete_value
    result,
  File "/usr/local/lib/python3.6/dist-packages/graphql/execution/execute.py", line 766, in complete_value
    cast(GraphQLList, return_type), field_nodes, info, path, result
  File "/usr/local/lib/python3.6/dist-packages/graphql/execution/execute.py", line 807, in complete_list_value
    "Expected Iterable, but did not find one for field"
TypeError: Expected Iterable, but did not find one for field Query.users.

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/usr/local/lib/python3.6/dist-packages/graphql/execution/execute.py", line 351, in execute_operation
    )(type_, root_value, path, fields)
  File "/usr/local/lib/python3.6/dist-packages/graphql/execution/execute.py", line 441, in execute_fields
    parent_type, source_value, field_nodes, field_path
  File "/usr/local/lib/python3.6/dist-packages/graphql/execution/execute.py", line 612, in resolve_field
    field_def.type, field_nodes, info, path, result
  File "/usr/local/lib/python3.6/dist-packages/graphql/execution/execute.py", line 688, in complete_value_catching_error
    self.handle_field_error(error, field_nodes, path, return_type)
  File "/usr/local/lib/python3.6/dist-packages/graphql/execution/execute.py", line 703, in handle_field_error
    raise error
  File "/usr/local/lib/python3.6/dist-packages/graphql/execution/execute.py", line 675, in complete_value_catching_error
    return_type, field_nodes, info, path, result
  File "/usr/local/lib/python3.6/dist-packages/graphql/execution/execute.py", line 750, in complete_value
    result,
  File "/usr/local/lib/python3.6/dist-packages/graphql/execution/execute.py", line 766, in complete_value
    cast(GraphQLList, return_type), field_nodes, info, path, result
  File "/usr/local/lib/python3.6/dist-packages/graphql/execution/execute.py", line 807, in complete_list_value
    "Expected Iterable, but did not find one for field"
graphql.error.graphql_error.GraphQLError: Expected Iterable, but did not find one for field Query.users.

来自 ariadne 的错误截图

4

1 回答 1

0

由于 prisma 还不支持 python 客户端，下面的代码有助于作为从 Ariadne 联系 prisma 服务器的解决方法。

from ariadne import gql, load_schema_from_path, QueryType, make_executable_schema 
from ariadne.asgi import GraphQL 

import requests 

prisma_url = "your-prisma-endpoint" 
schema_files_path = "/root/manisha/prisma/generated/prisma.graphql" 
schema = load_schema_from_path(schema_files_path) 

query = QueryType() 


def make_call_to_prisma(info): 
    data = info.context["request"]._body 
    resp = requests.post( 
        url=prisma_url, headers={"content-type": "application/json"}, data=data 
    ) 
    return resp 


@query.field("users") 
def resolve_users(_, info, where=None): 
    result = make_call_to_prisma(info) 
    print(result.json()) 
    return result.json()["data"]["users"] 


schema = make_executable_schema(schema, query) 
app = GraphQL(schema, debug=True)
于 2019-07-08T13:26:57.203 回答