(New on v1.4.1) Error: customValidator is not provided via NG_VALIDATORS or NG_ASYNC_VALIDATORS

[rahul-winner]

@udos86 & Team.

Although it looks very much related to this issue #271 .
However, I'm getting this error even in development build. On investigation, I noticed that the method "getCustomValidatorFn" of DynamicFormService is getting 'this.NG_VALIDATORS' as null. Consequently, it does not even check whether custom validator functions exists or not and eventually fails.

Please take a look on below image which shows the stack trace on debugger.

Note: I'm using ng2-dynamic-forms version : 1.4.4

I'm not sure if I'm missing something terribly here. Or if there is any known problem.

This is blocking our development as that custom validator is needed for a business validation. Kindly let me know if you need elaboration.

I'll be glad to get any kind of help.

Thanks a lot !!

[udos86]

@rahul-winner

I cannot verify any new bug here.

Both the sample application in this repository as well as my new alternate sample show how to implement custom validators.

Did you provide your validator function in your app module like this?

  providers: [
    { provide: NG_VALIDATORS, useValue: myCustomValidator, multi: true }
  ]

[rahul-winner]

thanks @udos86
It helped. I haven't added validator function in app module. I've added the function to app module and my validator stats working.

By the way I've couple of follow up queries:

• Why do we need to add validator function to add module. I could not see any such instruction in this blog as well. Is this needed only for forms using 'ng2-dynamic-forms'??

• I tried adding the validator function to my lazily loaded (sub module) module and it didn't work. I could make it only when I add the function to app (root) module. I am not able to understand why it didn't work with lazily loaded modules.

Answers to above queries will help me to understand dynamic forms better.

Thanks a lot !

[udos86]

@rahul-winner These are good questions!

Why do we need to add validator function to add module. I could not see any such instruction in this blog as well. Is this needed only for forms using 'ng2-dynamic-forms'?

Indeed, when using Reactive Forms (which ng2 Dynamics Forms relies on under the hood) there's no need to provide a validator function via NG_VALIDATORS.

However to provide JSON export for validators, ng2 Dynamic Forms let's you define a validator just by it's function name.

In order to recreate that model now from JSON the function name needs to be matched against some global injection token. That's why I utilize NG_VALIDATORS and Angulars multi provider mechanism here.

I tried adding the validator function to my lazily loaded (sub module) module and it didn't work. I could make it only when I add the function to app (root) module. I am not able to understand why it didn't work with lazily loaded modules.

Since DynamicFormService is provided forRoot() all NG_VALIDATORS need to be provided at app root level as well.

[rahul-winner]

Thanks a lot @udos86 for insight. It was helpful.

Nevertheless, I'd like to share one more observation. I noticed that that custom validator does not get invoked when I provide 'null' against it [like it worked for 'required' validator] in model something like below

{
            id: "config",
            label: "Config",
            validators: {
                required: null,
                **customCacheConfigValidator : null**
            },
            errorMessages: {
                required: "Field is required",
                customCacheConfigValidator : "Please provide valid value for cache config."
            }
        }

What do you say? Am I missing anything here? Or custom validator has to be provided with some non-null value for dynamic form model.

Thanks. Rahul