How to use array of objects for controls in Reactive Forms - forms

Question

I need to dynamic create textarea for forms. I have the following model:
this.fields = {
isRequired: true,
type: {
options: [
{
label: 'Option 1',
value: '1'
},
{
label: 'Option 2',
value: '2'
}
]
}
};
And form:
this.userForm = this.fb.group({
isRequired: [this.fields.isRequired, Validators.required],
//... here a lot of other controls
type: this.fb.group({
options: this.fb.array(this.fields.type.options),
})
});
Part of template:
<div formGroupName="type">
<div formArrayName="options">
<div *ngFor="let option of userForm.controls.type.controls.options.controls; let i=index">
<textarea [formControlName]="i"></textarea>
</div>
</div>
</div>
So, as you can see I have an array of objects and I want to use label property to show it in a textarea. Now I see [object Object]. If I change options to a simple string array, like: ['Option 1', 'Option 2'], then all works fine. But I need to use objects. So, instead of:
<textarea [formControlName]="i"></textarea>
I have tried:
<textarea [formControlName]="option[i].label"></textarea>
But, it doesn't work.
How can I use an array of objects?
This is Plunkr

Answer 1

You need to add a FormGroup, which contains your label and value. This also means that the object created by the form, is of the same build as your fields object.
ngOnInit() {
// build form
this.userForm = this.fb.group({
type: this.fb.group({
options: this.fb.array([]) // create empty form array
})
});
// patch the values from your object
this.patch();
}
After that we patch the value with the method called in your OnInit:
patch() {
const control = <FormArray>this.userForm.get('type.options');
this.fields.type.options.forEach(x => {
control.push(this.patchValues(x.label, x.value))
});
}
// assign the values
patchValues(label, value) {
return this.fb.group({
label: [label],
value: [value]
})
}
Finally, here is a
Demo

Answer 2

The answer from AJT_82 was so useful to me, I thought I would share how I reused his code and built a similar example - one that might have a more common use case, which is inviting several people to sign-up at once. Like this:
I thought this might help others, so that's why I am adding it here.
You can see the form is a simple array of text inputs for emails, with a custom validator loaded on each one. You can see the JSON structure in the screenshot - see the pre line in the template (thanks to AJT), a very useful idea whilst developing to see if your model and controls are wired up!
So first, declare the objects we need. Note that 3 empty strings are the model data (which we will bind to the text inputs):
public form: FormGroup;
private control: FormArray;
private emailsModel = { emails: ['','','']} // the model, ready to hold the emails
private fb : FormBuilder;
The constructor is clean (for easier testing, just inject my userService to send the form data to after submit):
constructor(
private _userService: UserService,
) {}
The form is built in the init method, including storing a reference to the emailsArray control itself so we can check later whether its children (the actual inputs) are touched and if so, do they have errors:
ngOnInit() {
this.fb = new FormBuilder;
this.form = this.fb.group({
emailsArray: this.fb.array([])
});
this.control = <FormArray>this.form.controls['emailsArray'];
this.patch();
}
private patch(): void {
// iterate the object model and extra values, binding them to the controls
this.emailsModel.emails.forEach((item) => {
this.control.push(this.patchValues(item));
})
}
This is what builds each input control (of type AbstracControl) with the validator:
private patchValues(item): AbstractControl {
return this.fb.group({
email: [item, Validators.compose([emailValidator])]
})
}
The 2 helper methods to check if the input was touched and if the validator raised an error (see the template to see how they are used - notice I pass the index value of the array from the *ngFor in the template):
private hasError(i):boolean {
// const control = <FormArray>this.form.controls['emailsArray'];
return this.control.controls[i].get('email').hasError('invalidEmail');
}
private isTouched(i):boolean {
// const control = <FormArray>this.form.controls['emailsArray'];
return this.control.controls[i].get('email').touched;
}
Here's the validator:
export function emailValidator(control: FormControl): { [key: string]: any } {
var emailRegexp = /[a-z0-9._%+-]+#[a-z0-9.-]+\.[a-z]{2,3}$/;
if (control.value && !emailRegexp.test(control.value)) {
return { invalidEmail: true };
}
}
And the template:
<form [formGroup]="form" (ngSubmit)="onSubmit(form.value)" class="text-left">
<div formArrayName="emailsArray">
<div *ngFor="let child of form.controls.emailsArray.controls; let i=index">
<div class="form-group" formGroupName="{{i}}">
<input formControlName="email"
class="form-control checking-field"
placeholder="Email" type="text">
<span class="help-block" *ngIf="isTouched(i)">
<span class="text-danger"
*ngIf="hasError(i)">Invalid email address
</span>
</span>
</div>
</div>
</div>
<pre>{{form.value | json }}</pre>
<div class="form-group text-center">
<button class="btn btn-main btn-block" type="submit">INVITE</button>
</div>
</form>
For what it's worth, I had started with this awful mess - but if you look at the code below, you might more easily understand the code above!
public form: FormGroup;
public email1: AbstractControl;
public email2: AbstractControl;
public email3: AbstractControl;
public email4: AbstractControl;
public email5: AbstractControl;
constructor(
fb: FormBuilder
) {
this.form = fb.group({
'email1': ['', Validators.compose([emailValidator])],
'email2': ['', Validators.compose([emailValidator])],
'email3': ['', Validators.compose([emailValidator])],
'email4': ['', Validators.compose([emailValidator])],
'email5': ['', Validators.compose([emailValidator])],
});
this.email1 = this.form.controls['email1'];
this.email2 = this.form.controls['email2'];
this.email3 = this.form.controls['email3'];
this.email4 = this.form.controls['email4'];
this.email5 = this.form.controls['email5'];
}
and the above used 5 of these divs in the template - not very DRY!
<div class="form-group">
<input [formControl]="email1" class="form-control checking-field" placeholder="Email" type="text">
<span class="help-block" *ngIf="form.get('email1').touched">
<span class="text-danger" *ngIf="form.get('email1').hasError('invalidEmail')">Invalid email address</span>
</span>
</div>

Answer 3

I guess it's not possible with FormControlName.
You could use ngModel .. take a look at your modified plunker:
http://plnkr.co/edit/0DXSIUY22D6Qlvv0HF0D?p=preview
#Component({
selector: 'my-app',
template: `
<hr>
<form [formGroup]="userForm" (ngSubmit)="submit(userForm.value)">
<input type="checkbox" formControlName="isRequired"> Required Field
<div formGroupName="type">
<div formArrayName="options">
<div *ngFor="let option of userForm.controls.type.controls.options.controls; let i=index">
<label>{{ option.value.label }}</label><br />
<!-- change your textarea -->
<textarea [name]="i" [(ngModel)]="option.value.value" [ngModelOptions]="{standalone: true}" ></textarea>
</div>
</div>
</div>
<button type="submit">Submit</button>
</form>
<br>
<pre>{{userForm.value | json }}</pre>
`,
})
export class App {
name:string;
userForm: FormGroup;
fields:any;
ngOnInit() {
this.fields = {
isRequired: true,
type: {
options: [
{
label: 'Option 1',
value: '1'
},
{
label: 'Option 2',
value: '2'
}
]
}
};
this.userForm = this.fb.group({
isRequired: [this.fields.isRequired, Validators.required],
//... here a lot of other controls
type: this.fb.group({
// .. added map-function
options: this.fb.array(this.fields.type.options.map(o => new FormControl(o))),
})
});
}
submit(value) {
console.log(value);
}
constructor(private fb: FormBuilder) { }
addNumber() {
const control = <FormArray>this.userForm.controls['numbers'];
control.push(new FormControl())
}
}

Answer 4

You may try this
Typescript:
ngOnInit(): void {
this.user = this.fb.group({
Title: ['1'],
FirstName: ['', Validators.required],
LastName: ['', Validators.required],
ContactNumbers: this.fb.array([
this.fb.group({
PhoneNumber: ['', [Validators.required]],
IsPrimary: [true],
ContactTypeId: [1]
})
]),
Emails: this.fb.array([
this.fb.group({
Email: ['', [Validators.required, Validators.email]],
IsPrimary: [true]
})
]),
Address: this.fb.group({
Address1: ['', Validators.required],
Address2: [''],
Town: [''],
State: ['UP'],
Country: [{ value: 'India', disabled: true }],
Zip: ['', Validators.required]
})
});
}
get Emails() {
return this.landlord.get('Emails') as FormArray;
}
Add and remove
addMoreEmail(index: number) {
if (index == 0) {
this.Emails.push(this.fb.group({ Email: ['', [Validators.required, Validators.email]], IsPrimary: [false] }));
} else {
this.Emails.removeAt(this.Emails.value.indexOf(index));
}
}
HTML
<form [formGroup]="user"
<div formArrayName="Emails">
<div *ngFor="let email of Emails.controls; let i=index">
<div class="row" [formGroup]="email">
<div class="col-sm-10">
<div class="form-group">
<label for="i" class="label">Email</label>
<input type="email" nbInput fullWidth id="i" placeholder="Email"
formControlName="Email" required>
</div>
</div>
<div class="col-sm-2 position-relative">
<nb-icon icon="{{i==0?'plus':'minus'}}-round" pack="ion"
(click)="addMoreEmail(i)">
</nb-icon>
</div>
</div>
</div>
</div></div>