What does 'locations' refer to in GraphQL errors?

Question

I'm working through a GraphQL Node/Prisma server tutorial and encountered an error due to something wrong in my code. I've solved the error but I want to understand the error message, in particular, what does locations refers to? That is, I have a location of line 2, column 3, but line 2, column 3 of what? The relevant method in my code (signup, in this case)? Of my mutation?

// error message 
{
  "data": {
    "signup": null
  },
  "errors": [
    {
      "message": "secretOrPrivateKey must have a value",
      "locations": [
        {
          "line": 2,
          "column": 3
        }
      ],
      "path": [
        "signup"
      ]
    }
  ]
}

score 15 · Accepted Answer · answered Mar 06 '19 at 19:39

Just like path, locations refers to where inside your GraphQL document the error occurred. You can see this for yourself using something like the SWAPI GraphQL endpoint. We can trigger a validation error by requesting a field that doesn't exist:

{
  allFilmz
}

The resulting error has this locations array:

[
  {
    "line": 2,
    "column": 3
  }
]

That's because the offending field is on line 2, starting with column 3. If we instead send:

{allFilmz}

we get:

[
  {
    "line": 1,
    "column": 2
  }
]

Generally, the path of the error will be more informative than the locations, but the path won't exist when there are syntax errors in your document -- in those cases, the locations are the only thing you can use to track down where your syntax error occurred.

Word of caution if using GraphQL Playground -- unlike GraphiQL, Playground will strip out comments and format your request before sending it, so the locations may not match what you see in the Playground UI.

What does 'locations' refer to in GraphQL errors?

1 Answers1