Creating Custom Tests

Please read the Anatomy of a Schema page before continuing.

Simple Custom Tests - Aka Zod's refine

All schemas contain the TestFunc() method which can be used to create a simple custom test in a similar way to Zod's refine method. The TestFunc() method takes a ValidateFunc as an argument. This is a function that takes the data as input and returns a boolean indicating if it is valid or not. If you return false from the function Zog will create a ZogIssue. For example:

z.String().TestFunc(func(data any, ctx z.Ctx) bool {
	return data == "test"
})

Test funcs for structs and slices instead receive a pointer to the data to avoid copying large data structures. For example:

z.Struct(z.Schema{
	"name": z.String(),
}).TestFunc(func(dataPtr any, ctx z.Ctx) bool {
	user := dataPtr.(*User)
	return user.Name == "test"
})

Pro tip It is very likely that you may want to set custom messages or paths, you can do that like with any other tests with TestOptions. For more on this checkout the Anatomy of a Schema page.

Complex Custom Tests - Aka Zod's superRefine

For complex tests you can use the schema.TestFunc() method but it is recommended that you use the schema.Test() method as it provides a bit more flexbility. This is quite simple to do using the zog context, lets look at an example that will execute a DB call to verify a user's session is valid:

sessionSchema := z.String().Test(z.Test{
  Func: func (val any, ctx z.Ctx) {
    session := val.(string)
    if !sessionStore.IsValid(session) {
      // This ctx.Issue() is a shortcut to creating Zog issues that are aware of the current schema context. Basically this means that it will prefil some data like the path, value, etc. for you.
      ctx.AddIssue(ctx.Issue().SetMessage("Invalid session"))
      return
    }
    if sessionStore.HasExpired(session) {
      // But you can also just use the normal z.Issue{} struct if you want to.
      ctx.AddIssue(z.Issue{
        Message: "Session expired",
        Path: "session",
        Value: val,
      })
      return
    }
    if sessionStore.IsRevoked(session) {
      ctx.AddIssue(ctx.Issue().SetMessage("Session revoked"))
      return
    }
    // etc
  }
})

Making Reusable Tests

In general I recommend you wrap you reusable tests in a function. Here are examples for both simple and complex tests:

// Notice how we can pass default values to the test which can then be overriden by the function called. This is super nice if you need it!
func MySimpleTest(opts ...z.TestOption) z.Test {
	options := []TestOption{
		Message("Default message, can be overriden"),
	}
	options = append(options, opts...)
  return z.TestFunc(
    func (val any, ctx z.Ctx) bool {
      return true // or any other validation
    },
   ...options
  )
}


func MyComplexTest() z.Test {
  return z.Test{
    Func: func (val any, ctx z.Ctx) {
      // complex test here
    }
  }
}