Add optional Type to FormattedError

[maxsz]

This is how github's API exposes machine-readable error strings. We need this in our API to better be able to handle specific errors in the client. This is just a proposal to start a discussion on how to best handle this requirement 😃

For example:

Query:

{
  repository(owner:"bla",name:"blubb") {
    id
  }
}

Response:

{
  "data": {
    "repository": null
  },
  "errors": [
    {
      "message": "Could not resolve to a Repository with the name 'blubb'.",
      "type": "NOT_FOUND",
      "path": [
        "repository"
      ],
      "locations": [
        {
          "line": 2,
          "column": 3
        }
      ]
    }
  ]
}

[coveralls]

Coverage increased (+0.01%) to 82.078% when pulling 816804e on equinux:formatted-error-type into 105a6c2 on graphql-go:master.

[coveralls]

Coverage decreased (-0.02%) to 82.054% when pulling 263d35c on equinux:formatted-error-type into ed4c4d8 on graphql-go:master.

[coveralls]

Coverage increased (+0.01%) to 82.054% when pulling 77d686b on equinux:formatted-error-type into 4b17eb6 on graphql-go:master.

[coveralls]

Coverage decreased (-0.1%) to 80.927% when pulling c2ae40a on equinux:formatted-error-type into 1c504cf on graphql-go:master.

[maxsz]

What do you think @sogko, @chris-ramon?

[christianpv]

@maxsz I believe we have to do something like this instead: graphql/graphql-js@0b2e81c#diff-f8e4bedf89ec2148ccb1602bfc6a7ae7

[maxsz]

@christianpv looks good! I've updated the PR 👍

[dvic]

I went with a different approach in #279 and chose just to store the original error with FormattedError and move the responsibility of rendering errors differently up the chain. This enables me easily to render my domain errors differently, since I now have access to the actual underlying error. Any thoughts on this approach?

[appleboy]

Any update on this?

[chris-ramon]

Thanks a lot @maxsz! — latest spec of GraphQL details how to expose additional information about errors via extensions:

{
  "errors": [
    {
      "message": "Name for character with ID 1002 could not be fetched.",
      "locations": [ { "line": 6, "column": 7 } ],
      "path": [ "hero", "heroFriends", 1, "name" ],
      "extensions": {
        "code": "CAN_NOT_FETCH_BY_ID",
        "timestamp": "Fri Feb 9 14:33:09 UTC 2018"
      }
    }
  ]
}

We have a PR for it, so closing this one in favor of: #363