Golang: Validate Struct Fields in Slice Items - json

Question

I'm new to Golang.
golang version: 1.17.8
validator: "github.com/go-playground/validator/v10"
I want to validate an incoming JSON payload after loaded into nested struct data structure.
Here's my incoming JSON payload,
{
"name": "Yomiko",
"address": {
"city": "Tokyo",
"street": "Shibaura St"
},
"children":[
{
"lastName": "Takayashi"
}
],
"isEmployed": false
}
Here's my user.go file,
package main
type User struct {
Name string
Address *Address `validate:"required"`
Children []*Child
IsEmployed *bool `validate:"required"`
}
type Address struct {
City string `validate:"required"`
Street string `validate:"required"`
}
type Child struct {
Title string `validate:"required"`
FirstName string
LastName string `validate:"required"`
}
Here's my test function,
func TestUserPayload(t *testing.T) {
actualUserPayload := NewUserPayloadFromFile("userpayload.json")
validate := validator.New()
err := validate.Struct(actualUserPayload)
if err != nil {
t.Error("Validation Error: ", err)
}
}
This test passes. However, I expected it to fail as Child.Title is marked as required. I expected the following error,
Validation Error: Key: 'Child.Title' Error:Field validation for 'Title' failed on the 'required' tag
However, when I loop through the children slice and validate each child struct as follows the test fails as expected,
func TestUserPayload(t *testing.T) {
actualUserPayload := NewUserPayloadFromFile("userpayload.json")
validate := validator.New()
err := validate.Struct(actualUserPayload)
if err != nil {
t.Error("Validation Error: ", err)
}
children := actualUserPayload.Children
for _, child := range children {
err := validate.Struct(child)
if err != nil {
t.Error("Validation Error: ", err)
}
}
}
Is there a straightforward way to do this validation of the items in a slice of structs?

Answer 1

According to the documentation of the validator package, you can use dive in your struct tag to get this behavior. This causes the validator to also validate the nested struct/slice/etc.
So you would need to update your User struct to this:
type User struct {
Name string
Address *Address `validate:"required"`
Children []*Child `validate:"dive"`
IsEmployed *bool `validate:"required"`
}
Here it is working in Go Playground