Validate single field in multifield struct

[ycharron]

Given:

var SignupFormSchema = z.Struct(z.Shape{
	"name":  z.String().Required(z.Message("Name is required")).Max(64, z.Message("Name should not exceed 64 characters")),
	"email": z.String().Required(z.Message("Email is required")).Email(z.Message("Email is not valid")).Max(128, z.Message("Email should not exceed 128 characters")),
	"password": z.String().Required(z.Message("Password is required")).Min(8, z.Message("Password should be at least 8 characters long")).Max(64, z.Message("Password should not exceed 64 characters")).TestFunc(func(password *string, _ z.Ctx) bool {
		return !IsWeakPassword(*password)
	}, z.Message("Password is weak")),
})

errs := SignupFormSchema.Validate(f)

Is it possible to validate only 1 field? e.g. name

Thanks

[Oudwins]

Hey! I'm not sure from the question if you want to use a schema in a struct schema to validate a value or if you want to validate a struct with a subset of fields from a struct schema.

For the first the only way to do it right now is:

var MyFieldSchema = z.String() 

var MyStructSchema = z.Struct(z.Shape{
"Field": MyFieldSchema,
})

// validate a string value
MyFieldSchema.Validate(&f) 

For the second you would need to use pick or merge see the docs on those utility fns

[ycharron]

I would like to avoid code duplication, as well as extra processing time. I know I can call the Validate() function, and only look for "name" errors.

As per my code above, a call to Validate(), will validate the whole struct (i.e. name, email, password). Is it possible to cherry pick which specific field to validate?

e.g. errs := SignupFormSchema.Validate(f, "name") (I'm aware this is not possible, but shows intent)

My current solution is code duplication. For example, to validate the "name" only:

func (f *SignupForm) ValidateName() z.ZogIssueMap {
	issues := z.String().
		Required(z.Message("Name is required")).
		Max(64, z.Message("Name should not exceed 64 characters")).
		Validate(&f.Name)
	f.NameHasError = len(issues) != 0
	if len(issues) == 0 {
		return z.ZogIssueMap{}
	}
	return z.ZogIssueMap{"name": issues}
}

Thanks for your help!

[Oudwins]

Yes you can do that through the pick method. see the docs: https://zog.dev/reference#complex-types

You would just do

formWithOnlyNameSchema:= formSchema.Pick("name")
formWithOnlyNameSchema.Validate(&form) // will only check the name field and ignore all the rest (i.e keep them as is)

edit: this is not very well documented in the docs. Probably should add a section on composability of schemas.

edit2: You can also do what you are doing and avoid code duplication by just having a local private global that has that specific schema like I mentioned in my first comment:

type SignupForm struct {
   Name string
}
var signupFormNameSchema = z.String().
		Required(z.Message("Name is required")).
		Max(64, z.Message("Name should not exceed 64 characters"))
// note this is public
var SignupFormSchema = z.Struct(z.Shape{
   "Name": signupFormNameSchema
 })
func (f *SignupForm) ValidateName() z.ZogIssueList {
      return signupFormNameSchema.Validate(&f.Name)
}