Siren Error Extension Proposal

siren-error.json

{
    "class": [
        "error",
        "UnprocessableEntity",
        "api"
    ],
    "properties": {
        "message": "Unprocessable entity. The submission failed resource validation.",
        "code": 422
    },
    "entities": [
        {
            "class": [
                "error",
                "validation",
                "maxlength"
            ],
            "properties": {
                "message": "The maximum length is 64 characters.",
                "id": "title"
            }
        },
        {
            "class": [
                "error",
                "validation",
                "pattern"
            ],
            "properties": {
                "message": "The list price must be a valid US currency.",
                "id": "listPrice"
            }
        }
    ],
    "actions": [
        {
            "name": "retry",
            "href": "/albums",
            "method": "POST",
            "fields": [
                {
                    "type": "text",
                    "name": "title",
                    "maxLength": 64
                },
                {
                    "type": "number",
                    "name": "listPrice",
                    "pattern": "[+-]?[0-9]{1,3}(?:,?[0-9]{3})*(?:\\.[0-9]{2})?"
                }
            ]
        }
    ],
    "links": [
        {
            "rel": [
                "index"
            ],
            "href": "/albums"
        }
    ]
}

I like that @eric. How about also including the POST/PATCH/PUT parameters as properties?

Echoing back user inputs can result in exploitable attack vectors. I'd advise people to check the server logs for debugging.

Gist updated.

A more compact version utilizing the non-standard entityAttributes:

{
    "class": [
        "error",
        "UnprocessableEntity",
        "api"
    ],
    "properties": {
        "message": "Unprocessable entity. The submission failed resource validation.",
        "code": 422
    },
    "entityAttributes": {
        "class": [
            "error",
            "validation",
            "maxlength"
        ]
    },
    "entities": [
        {
            "properties": {
                "message": "The maximum length is 64 characters.",
                "id": "title"
            }
        },
        {
            "properties": {
                "message": "The list price must be a valid US currency.",
                "id": "listPrice"
            }
        }
    ],
    "actions": [
        {
            "name": "retry",
            "href": "/albums",
            "method": "POST",
            "fields": [
                {
                    "type": "text",
                    "name": "title",
                    "maxLength": 64
                },
                {
                    "type": "number",
                    "name": "listPrice",
                    "pattern": "[+-]?[0-9]{1,3}(?:,?[0-9]{3})*(?:\\.[0-9]{2})?"
                }
            ]
        }
    ],
    "links": [
        {
            "rel": [
                "index"
            ],
            "href": "/albums"
        }
    ]
}