Catch certain errors in the API and return information about them as response

[matthiasschaub]

Description

Per default errors which arise during validation of an API request (pydantic models) are caught by FastAPI and details are returned in the API response (ReqestValidationError). Cases covered by this are:

• invalid set/combination of parameter
• invalid bpolys (Valid GeoJSON and allowed Geometries)

This PR will extend the numbers of errors about which FastAPI will return details.
In particular it will add custom exception handlers to FastAPI (FastAPI docs). Thise will cover two more cases:

• OhsomeApiError`: If status code of ohsome API response is 4xx or 5xx or if response is invalid even though status code is 200 (Happens if response is streamed)
• SizeRestrictionError: bpolys exceeds geometry size limit

In addition this PR seeks to unify the response schema for errors raised during API request parameter validation (pydatic models) and those covered by the custom exception handlers. This is not as straightforward as it sounds since the ReqestValidationError contains information about multiple errors ("One exception will be raised regardless of the number of errors found, that ValidationError will contain information about all the errors and how they happened." (pydantic docs). In effect to each response only the error type is added.

Current response schema for custom errors:

{'detail': 'Input GeoJSON Object is too big. The area should be less than 100 km².'}

Current response schema for validation errors:

{
  "detail": [
    {
      "loc": [
        "body",
        "dataset"
      ],
      "msg": "value is not a valid enumeration member; permitted: 'regions'",
      "type": "type_error.enum",
      "ctx": {
        "enum_values": [
          "regions"
        ]
      }
    },
    {
      "loc": [
        "body",
        "layerName"
      ],
      "msg": "field required",
      "type": "value_error.missing"
    }
  ]
}

Changed response schema for custom errors:

{"detail": "message", "type": "OhsomeApiError"}

Changed response schema for custom errors:

{
  "detail": [
    {
      "loc": [
        "body",
        "dataset"
      ],
      "msg": "value is not a valid enumeration member; permitted: 'regions'",
      "type": "type_error.enum",
      "ctx": {
        "enum_values": [
          "regions"
        ]
      }
    },
    {
      "loc": [
        "body",
        "layerName"
      ],
      "msg": "field required",
      "type": "value_error.missing"
    }
  ],
  "type": "RequestValidationError"
}

Open Issues

This should probably be its own PR -> #207:

• If the input is a GeoJSON FeatureCollection no information will passed down to the API for which feature the error ocured.
  • Possible solution is to use feature.id in each error message.

Corresponding issue

Closes #107

Related #103

Checklist

• I have updated my branch to main (e.g. through git rebase main)
• My code follows the style guide and was checked with pre-commit before committing
• I have commented my code
• I have added sufficient unit and integration tests
  • Missing tests for reports
• I have updated the CHANGELOG.md

[joker234]

👍 some minor remarks ;)