Usage

Validating JSON

To validate body JSON, use the validate_json() decorator:

@app.route('/')
@validate_json(schema)
async def hello(request):
    return text("OK")

If all fields in schema are optional, then an empty JSON object {} will be accepted, but an empty request body will be rejected.

Validating querystring arguments

To validate querystring arguments, use the validate_args() decorator:

@app.route('/')
@validate_args(schema)
async def hello(request):
    return text("OK")

All argument values are strings. To use validation rules for other types use coercion rules (see Normalization).

Error response format

In case of an error the request returns with status of 400. Example error response:

{
    "error": {
        "invalid": [
            {
                "constraint": true,
                "entry": "name",
                "entry_type": "json_data_property",
                "rule": "required"
            }
        ],
        "message": "Validation failed.",
        "type": "validation_failed"
    }
}

Fields definitions:

type:

machine readable description of the problem

message:

user readable description of the problem

invalid:

list containing all validation errors

entry_type:

type of the incorrect entry (json data, querystring parameter, etc)

entry:

path to the incorrect entry

rule:

rule that failed validation

constraint:

expected value for the rule

Schema

sanic-validation uses Cerberus as the validation library. For the list of available rules see Cerberus’ schema documentation.

Normalization

Normalization for the purpose of validation is supported, but you’ll have to manually coerce types in the request handler. See Cerberus’ normalization documentation for the list of normalization rules.

Extending

Custom rules, data types and coercers can be easily added. Consult Cerberus’ customization documentation for details.