Support for own error messages

[lobodpav]

Would be great to be able to specify custom error message for each property constraint so that jassi would use it as message instead of the default text.

This is handy when developing REST services and want to use custom messages being returned to the caller.

[iclanzan]

Sounds interesting and I’m open for pull requests. Do you want to implement this?

[lobodpav]

Would be glad to implement this.

However, I've been thinking about this issue a bit now and I can see a showstopper.

To be able to specify an error message per each validation keyword, it would mean to extend validation keywords. Either it would contain a value so that default error message is returned, or it would contain an object with value and message to return in case of validation error.

Example:

{
    "type": "object",
    "properties": {
        "firstName": {
            "type": {
                "value": "string",
                "message": "STRING type required"
            },
            "minLength": {
                "value": "6",
                "message": "First name must be 6 characters long at least"
            }
        },
        "lastName": {
            "type": "string"
        },
    },
    "required": [
        {
            "value": "firstName",
            "message": "First name is required"
        },
        {
            "value": "lastName",
            "message": "Last name is mandatory"
        }
    ]
}

The problem is, that this is not a valid JSON schema according to v4 spec.

Any idea on how to overcome this issue?