Schema Stitching扩展Mutation传递参数报错求助

问题代码 #

extend type Mutation {
  space(value: SpaceInput): Int! @delegate(schema: "matterport", path: "space(value: $arguments:value)")
}

错误信息 #

{
  "errors": [
    {
      "message": "The variable `__arguments_value` is not compatible with the type of the current location.",
      "locations": [
        {
          "line": 2,
          "column": 5
        }
      ],
      "path": [
        "space"
      ],
      "extensions": {
        "variable": "__arguments_value",
        "variableType": "SpaceInput",
        "locationType": "SpaceInput!",
        "specifiedBy": "http://spec.graphql.org/October2021/#sec-All-Variable-Usages-are-Allowed",
        "remote": {
          "message": "The variable `__arguments_value` is not compatible with the type of the current location.",
          "path": [
            "space"
          ],
          "extensions": {
            "variable": "__arguments_value",
            "variableType": "SpaceInput",
            "locationType": "SpaceInput!",
            "specifiedBy": "http://spec.graphql.org/October2021/#sec-All-Variable-Usages-are-Allowed"
          }
        },
        "schemaName": "matterport"
      }
    }
  ]
}

问题根源 #

1. 参数必填性不匹配：远程matterport schema中，space mutation的value参数是必填类型SpaceInput!，但本地扩展的Mutation里定义的value是可选类型SpaceInput，导致传递的变量可能为null，不符合远程的非空要求。
2. @delegate变量引用语法错误：路径中的变量引用应该用$arguments.value而非$arguments:value，冒号是错误语法，会导致变量映射异常。

修复后的代码 #

extend type Mutation {
  space(value: SpaceInput!): Int! @delegate(schema: "matterport", path: "space(value: $arguments.value)")
}

验证要点 #

• 确保本地定义的参数类型（包括必填性）和远程schema完全一致
• 检查@delegate指令的path参数中，变量引用的语法符合你使用的Schema Stitching工具规范（比如GraphQL Tools中使用$arguments.参数名引用当前字段的参数）

内容的提问来源于stack exchange，提问作者Patrik Urban