Common validation errors

[!TIP]

• Learn more about this in GraphQL spec.
• See how the validation is implemented in TS.

Requesting non-existent fields

• The field that client wants to request must have been defined in the schema on that type.
• E.g. you cannot request getTodos to return todos with deadline since we never defined it in Todo object in our schema.

{
  "errors": [
    {
      "message": "Cannot query field 'deadline' on type 'Todo'.",
      "locations": [{ "line": 4, "column": 5 }]
    }
  ]
}

When a query returns an array of objects then you have to specify what you want

• E.g. if you just say query { getTodos } you’ll get:

  {
    "errors": [
      {
        "message": "Field 'getTodos' of type 'Todo' must have a selection of subfields. Did you mean 'getTodos { ... }'?",
        "locations": [{ "line": 3, "column": 3 }]
      }
    ]
  }
  

Trying to query fields of a scalar or enum doesn’t make sense, Right?

{
  "errors": [
    {
      "message": "Field 'name' must not have a selection since type 'String!' has no subfields.",
      "locations": [{ "line": 4, "column": 10 }]
    }
  ]
}

Missing inline fragments in queries for APIs that return a union

E.g. if you’re searching in audit-log and try { search(tags: ["warn"]) { serialNumber } } query you will get an error like this:

{
  "errors": [
    {
      "message": "Cannot query field 'serialNumber' on type 'EventSource'. Did you mean to use an inline fragment on 'Robot'?",
      "locations": [{ "line": 5, "column": 5 }]
    }
  ]
}

Cannot use a named fragment inside itself

Request errors

• Client has made a syntax error.
• location key tells you where is the syntax issue located in your query.
• No data key inside the response since GraphQL service returned the response before our request reaches its destined resolver.

Field errors

• Raised if something unexpected happens during execution.
• E.g. here we are mocking what will our server returns when something goes wrong in the middle of execution.
• GraphQL will attempt to continue executing the other fields and return a partial response.
• data key + errors key in the returned response.

Network errors

• They ain’t specific to GraphQL.
• Your lib of choice for GraphQL might have retries mechanisms implemented, so you just need to configure it.