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Depth limit validator key error if fragment undefined

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Assessment

Difficulty
2/5
Estimated time
1-3 hours
Newbie friendliness
55/100
Issue type
Bug
Clarity
Clearly specified
Activity status
Stale
Tech stack
graphql, python

Research direction

Inspect graphene/validation/depth_limit.py around line 148, then reproduce the undefined-fragment query with depth_limit_validator configured on GraphQLView. Ensure this case produces the standard unknown-fragment validation response instead of a KeyError or 500 error.

Written by the indexing model from the issue text.

Description

🐛 bug

Current behaviour:
When using the depth_limit_validator (docs), an invalid query can lead to a KeyError being thrown (from here), which usually results in the API returning a 500 server error.

To reproduce:

  • Add the depth_limit_validator to the validation_rules in your GraphQLView.
  • Execute a query with an undefined fragment, i.e. something like:
query {
  validQuery {
    validField
    ...undefinedFragment
  }
}

Expected behaviour:
A standard validation error response, like:

{
  "errors": [
    {
      "message": "Unknown fragment 'undefinedFragment'.",
      "locations": [
        {
          "line": x,
          "column": y
        }
      ]
    }
  ]
}

Since this is something that's caught by the standard validators, depth_limit_validator should probably just skip such errors. Or, do whatever the other validators do when they hit an "unrelated" error.

Environment:

  • Version: 3.3
  • Platform: n/a
Dominant language
Python
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