Fixed missing keys from returned errors in map validation

Fixes Or Enhances

Bug Description:

The ValidateMapCtx function calls the VarCtx(ctx context.Context, field interface{}, tag string) (err error) method, but the returned errors do not contain keys.

package main

import (
    "fmt"

    "github.com/go-playground/validator/v10"
)

func main() {
    validate := validator.New()

    data := map[string]interface{}{"email": "emailaddress"}
    rules := map[string]interface{}{"email": "required,email"}
    errs := validate.ValidateMap(data, rules) // when VarCtx is called
    fmt.Println(errs)
    //output: map[email:Key: '' Error:Field validation for '' failed on the 'email' tag]
}

Fix:

Added a new method VarWithKeyCtx(ctx context.Context, key string, field interface{}, tag string) (err error) to support validating a single variable, ensuring that the returned error contains the key of the field. This retains compatibility with the current VarCtx(...) method. Now, ValidateMapCtx will call the new VarWithKeyCtx(...) method.

package main

import (
    "fmt"

    "github.com/go-playground/validator/v10"
)

func main() {
    validate := validator.New()

    data := map[string]interface{}{"email": "emailaddress"}
    rules := map[string]interface{}{"email": "required,email"}
    errs := validate.ValidateMap(data, rules) // when the new VarWithKeyCtx is called
    fmt.Println(errs)
    //output: map[email:Key: 'email' Error:Field validation for 'email' failed on the 'email' tag]
}

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[x] Tests exist or have been written that cover this particular change.

@go-playground/validator-maintainers

go-playground / validator