Ngx-stream2form NPM

ngx-stream2form

Set a property of an object with an Angular form based on the structore of the event's payload of an RxJS stream

Demo

https://stackblitz.com/github/eshcharc/ngx-stream2form

Installing

npm install --save ngx-stream2form

Usage

Assuming this.people$ is a stream of people, represented by the model

interface Person {
  name: string;
  height: number;
  hobbies: string[];
}

and personFormGroup is set to be a component property.

Inside ngOnInit we call:

stream2Form.call(this, {
  propertyName: 'personFormGroup',
  streamSelector: this.people$
});

Notice that the static function has to be invoked within the context of the component.

Validators

You can pass validator/s as-is (for primitives) or an object, reflecting the structure of your model.

Primitives:

stream2Form.call(this, {
  propertyName: 'personFormGroup',
  streamSelector: this.people$,
  validators: Validators.required
});

stream2Form.call(this, {
  propertyName: 'personFormGroup',
  streamSelector: this.people$,
  validators: [Validators.min(0), Validators.max(9)]
});

Object:

stream2Form.call(this, {
  propertyName: 'personFormGroup',
  streamSelector: this.people$,
  validators: {
    name: Validators.required,
    height: [Validators.min(0), Validators.max(9)]]
  }
});

Notice that the hobbies property is missing, and thus will be omitted from validation, but kept as form control.

Array property

Array property can be passed a simple validator/s to validate every item in the list, or an object with index key/s to validate a single or specific items.

Validating the whole array with a validation set:

stream2Form.call(this, {
  propertyName: 'personFormGroup',
  streamSelector: this.people$,
  validators: {
    hobbies: [Validators.min(0), Validators.max(9)]
  }
});

Validating specific items:

stream2Form.call(this, {
  propertyName: 'personFormGroup',
  streamSelector: this.people$,
  validators: {
    "0": [Validators.min(0), Validators.max(9)],
    "3": Validators.required
  }
});

Selector Function:

Validators can be passed via a selector function. The selector is given the current model as a parameter, and the returned value determines the validator/s for the form (returned as a primitive, array or an object).

stream2Form.call(this, {
  propertyName: 'personFormGroup',
  streamSelector: this.people$,
  validators: (person: Person) => ({
    height: (person.height > 193) ? Validators.required : undefined
  })
});

Tranform to raw model

By setting the flag generateForm to false, the component's property is overriden with the raw model instead of the form.

stream2Form.call(this, {
  propertyName: 'personFormGroup',
  streamSelector: this.people$,
  generateForm: false
});

Subscribe to form events

It is possible to hide form subscriptions such as valueChanges and statusChanges and perform any other operation on the form after being generated with the formChanged hook

stream2Form.call(this, {
  propertyName: 'personFormGroup',
  streamSelector: this.people$,
  formChanged: (form) => {
    return [
      form.valueChanges.subscribe(...),
      form.statusChanges.subscribe(...)
    ];
  }
});

It is important to return an array of subscriptions to be managed by the tool, otherwise, bad things will happen (such as memory leaks).

Planned features

Include model properties: Only transform properties that are mentioned in the include entity into form entities. Keep other properties as object properties.
Exclude model properties: Omit transforming properties that are mentioned in the exclude entity into form entities. Keep transforming other properties into form entities.
Set the depth level the form will be generated to.