Gin Binding validations does not work when request body is Array of objects

Gin's request validation feature is not working when the request body (JSON) represents an array of objects

Ex:

type item struct {
    Field1 string `binding:"required"`
    Field2 string `binding:"required"`
}

var items []item

err := c.BindJSON(&items)

To be more clear, the validation logic in gin is expecting the root object to be a struct and hence bails out when an array type gets passed.

Comment From: ycdesu

Yes, this is an expected behavior. From the StructValidator interface, it says 'If the received type is not a struct, any validation should be skipped and nil must be returned.'.

Comment From: benereich

Even though this might be expected behaviour per interface definition, I was surprised to see binding:"required" lose its effect without any warnings or complaints at least at runtime.

Comment From: khier996

@ycavatars So, what is best way to validate each object in an array passed in the body?

Comment From: thinkerou

@khier996 yes, closing.

Comment From: rstrlcpy

the issue was closed without answer the last question:

what is best way to validate each object in an array passed in the body?

Could someone answer it?

I define a required struct field as a pointer and later check such fields for nil, but maybe there is not so dirty way?

Comment From: miaojiuchen

+1

Comment From: c1800054work

use

type AutoGenerated []struct {
    OrgID   string `json:"org_id"`
    GroupID string `json:"group_id"`
}

https://mholt.github.io/json-to-go/

Comment From: memochou1993

use dive

Items    []Item `json:"mails" binding:"dive"`

Comment From: ns-kliu

use dive

go Items []Item `json:"mails" binding:"dive"`

Thanks @memochou1993 , it really helps me to validate all objects in an array.

Comment From: fzf404

用dive

go Items []Item `json:"mails" binding:"dive"`

thank you!

Comment From: noname007

Use UnmarshalJSON to change the decode behavior

type item struct {
    Field1 string `binding:"required"`
    Field2 string `binding:"required"`
}


type itemArr []item
func (p *itemArr) UnmarshalJSON(b []byte) error {
    //fmt.Println(string(b))
    //json.Unmarshal(b, &p)--- wrong
    //json.Unmarshal(b, p) --- wrong
    var t []item
    json.Unmarshal(b, &t)
    *p = t
    return nil
}

var items itemArr
err := c.BindJSON(&items)