Complie error: ut.MyUserType.Validate undefined

[KobayashiTakaki]

Hi,

There is a situation that the generated codes result compile error.
The error goes like: ut.MyUserType.Validate undefined.

Here is my design code.

package design

import (
	. "github.com/shogo82148/goa-v1/design"
	. "github.com/shogo82148/goa-v1/design/apidsl"
)

var Author = Type("Author", func() {
	Attribute("name", String)
	Attribute("country", String)
	Required("name")
})

var Book = Type("Book", func() {
	Attribute("title", String)
	Attribute("author", Author)
})

The Author type has string "name" attribute and string "country" attribute.
The Required validation is set to the Author's "name" attribute.

The Book type has string "title" attribute and refers Author type as "author" attribute.

When I run codegen with this code, I get that compile error.

After investigation, I found two problems.

1. User type validation should not execute Validate of other types when the other type has only Required validation on primitive type attributes.
2. Validate method for public type should not be generated when the type has only Required validation on primitive type attributes.

Details are following.

Problem 1: Improper execution of other types' Validate

When the type has only Required validation on primitive type attributes, the type will not have validation code (in design of goa, as mentioned in Validator's recurseAttribute method).

So, the type referring such type (which has only Required validation for primitives) as an attribute should not call Validate method on that type.

However, the code generation procedure produces codes which call Validate on the other types regardless it's validation (having Validate method or not).

I think this problem should be fixed by changing here

goa-v1/goagen/codegen/validation.go

Line 255 in 6373905

if hasValidations {

to this.

		if hasValidations && catt.Validation != nil && !catt.Validation.HasRequiredOnly() {

This if statement is for decision whether generate codes calling Validate on the attribute or not.
This should consider situations that the referring type does not have Validate method.

Problem 2: Unnecessary generation of Validate

By changing my design code as like this (two String type attributes for Required),

var Author = Type("Author", func() {
	Attribute("name", String)
	Attribute("country", String)
	Required("name", "country")
})

codegen generates empty Validate method (just return) for this type.

// Validate validates the Author type instance.
func (ut *Author) Validate() (err error) {

	return
}

I think this is a bug of the code generation, because required String type will be primitive string, and validations for Required of primitive types should not be generated.

This problem can be fixed by changing here

goa-v1/goagen/codegen/validation.go

Line 382 in 6373905

if i > 0 {

to this.

			if i > 0 && val != "" {

This if statement is for adding line breaks between required validation codes.
Current condition (just if i > 0) will append "\n" even if the required attribute is primitive type (which will not produce validation code).
I think adding line breaks in the for loop should be done when the current code is not empty.

Codes

Here is my codes for testing codegen behavior.
https://github.com/KobayashiTakaki/goa-test

Thanks😌

[shogo82148]

fixed by #160