ckanext-validationapi

This plugin belongs to a set of plugins for the Datenregister – the non-public CKAN instance that is part of Berlin's open data portal daten.berlin.de.

ckanext-validationapi provides an API as a public wrapper around the internal validator functions of CKAN.

The plugin implements the following CKAN interfaces:

• IBlueprint
• IConfigurer

Requirements

This plugin has been tested with CKAN 2.9 (which requires Python 3).

Using the API

All validator functions that are available through ckan.plugins.toolkit.get_validator() can be used. The list of standard validators that CKAN offers is available at https://docs.ckan.org/en/latest/extensions/validators.html. Plugins can add more validators by implementing the IValidators interface.

The API is accessible via $CKAN_URL/api/validation; currently its only method is validate. Only POST requests with content type application/json are accepted.

The expected payload to validate is a JSON object with two attributes:

• validator: The name of the validator as it would be passed to ckan.plugins.toolkit.get_validator().
• value: The value we want to submit for validation.

Here is an example:

  {
    "validator": "email_validator" ,
    "value": "[email protected]"
  }

If the validator exists, validationapi will call the validator function with the provided value. The response will be a JSON object with these attributes:

• validator: The name of the validator as it would be passed to ckan.plugins.toolkit.get_validator().

• value: The value that was submitted for validation.

• success: Whether or not value passed the validation.

  • result: If successful, the output of the validator. This will often be the same as value, but sometimes the validator will perform some transformation as well.
  • message: If not successful, this will contain an error message as provided by the validator.

Here are some examples for communicating with the validation API via curl:

Valid input, unchanged

  curl -X POST \
       --data '{ "validator": "email_validator", "value": "[email protected]" }' \
       -H "Content-Type: application/json" \
       $CKAN_URL/api/validation/validate

  {
    "validator": "email_validator",
    "value": "[email protected]",
    "success": true,
    "result": "[email protected]"
  }

Valid input, changed

  curl -X POST \
       --data '{ "validator": "isodate", "value": "2004-10-10" }' \
       -H "Content-Type: application/json" \
       $CKAN_URL/api/validation/validate

  {
    "validator": "isodate",
    "value": "2004-10-10",
    "success": true,
    "result": "2004-10-10 00:00:00"
  }

Invalid input

  curl -X POST \
       --data '{ "validator": "isodate", "value": "2004-10-10x" }' \
       -H "Content-Type: application/json" \
       $CKAN_URL/api/validation/validate

  {
    "message": "Invalid: u'Datumsformat ung\\xfcltig.'",
    "validator": "isodate",
    "value": "2004-10-10x",
    "success": false
  }

Errors

If possible, validationapi will catch errors and provide an error message in the same format as above, but with the HTTP Response Code 400 (Bad Request). Below are some examples:

Unknown Validator

  curl -X POST \
       --data '{ "validator": "foolidator", "value": "barbar" }' \
       -H "Content-Type: application/json" \
       $CKAN_URL/api/validation/validate

  {
    "validator": "foolidator",
    "value": "barbar",
    "success": false,
    "error": {
      "message": "Bad Request - Validator `foolidator` does not exist",
      "code": 7
    }
  }

Wrong Request Format

  curl $CKAN_URL/api/validation/validate

  {
    "validator": null,
    "value": null,
    "success": false,
    "error": {
      "message": "Bad Request - Validation API accepts only POST requests with content type 'application/json'.",
      "code": 1
    }
  }

Error Codes

The complete list of error codes is:

• Wrong HTTP method = 1
• Wrong content type = 2
• No request data found = 3
• Cannot decode JSON = 4
• Wrong type of JSON = 5
• Wrong JSON structure = 6
• Unknown validator = 7
• Validator has unexpected number of arguments = 8
• Unexpected error = 20

License

This material is copyright © BerlinOnline Stadtportal GmbH & Co. KG.

This extension is open and licensed under the GNU Affero General Public License (AGPL) v3.0. Its full text may be found at:

http://www.fsf.org/licensing/licenses/agpl-3.0.html