iota results in missing parameter

[MattNewberry]

Synopsis:
When using iota to default a const group to a 0 value, and sending a 0 value via a JSON payload, the binding process fails believing the required value is missing.

Schema:

const (
    EventTypeEntry = iota
    EventTypeExit
)

Event struct {
        Type      int    `bson:"type" json:"type" binding:"required"`
        Timestamp string `bson:"timestamp" json:"timestamp" binding:"required"`
    }

JSON:

{
    "events": [
        {
            "timestamp": "2014-08-18T14:03:26.761-0400",
            "type": 0
        }
    ]
}

Response:

[GIN] 2014/08/18 - 14:08:03 | 400 |     78.894us | 127.0.0.1:52575 POST /v1/events
Error #01: Required Type 
     Meta: Operation aborted

[manucorporat]

I know, we are working in a completely new validation system
#67

[manucorporat]

@MattNewberry check out the new validation options: http://godoc.org/gopkg.in/bluesuncorp/validator.v5
Gin now uses that library internally, so you could use:

Event struct {
        Type      int    `bson:"type" json:"type" binding:"min=0,max=2"`
        Timestamp string `bson:"timestamp" json:"timestamp" binding:"required"`
}

how does it sounds?

[nazwa]

Nicely done with the new form validation. I can't test it any time soon, but do you think this will have any noticeable performance impact on simple forms?

[manucorporat]

@nazwa i don't think so, we just added one more branch: if structField.Kind() == reflect.Struct {
anyway I just optimized it a little bit:
967e623