Angular 2+ - Adding DOM elements dynamically in HTML FORM

Question

I am trying to create a page which users can use to create custom forms. I will be giving the user a drop-down menu. From that drop-down menu, user will be able to select the type of question - like text box, radio button, check box, date and etc. - and then based on that selection, I want to add that type of input into my DOM form. On submit, I want to store the value of these questions in JSON format.

Any suggestions? What is best approach to tackle this or how I can implement it?

Answer 1

You don't need any package, the best way to do this is like this:

<div ngbDropdown class="nav-item dropdown cursor">
    <a class="nav-link" ngbDropdownToggle>
        DropDown
    </a>
    <div ngbDropdownMenu class="dropdown-menu">
        <a class="dropdown-item" (click)="option1 = !option1">
            Form 1
        </a>
        <a class="dropdown-item" (click)="option2 = !option2">
            Form 2
        </a>
    </div>
</div>

<form #form="ngForm">
    <div class="form-option1" *ngIf="option1Selected">
        <!-- YOUR FORM 1 -->
    </div>
    <div class="form-option2" *ngIf="option2Selected">
        <!-- YOUR FORM 2 -->
    </div>
    ...

    <button type="submit"></button>
</form>

And them in your component:

option1 = "false";
option2 = "false";

The doc of *ngIf is here

Answer 2

Have a look at ng-dynamic-forms. I've used it on a project before and it really helped creating forms dynamically.

It even provides an import / export functionality which you could use to store the form/questions including the provided answers in JSON format.

sidenote: I am in no way connected to the mentioned project.

Answer 3

EDIT: I feel an example like in this stackblitz shows how much control you have in terms of dynamic forms with the basic Angular utilities.

https://stackblitz.com/edit/deep-nested-reactive-form?file=app%2Fapp.component.html

Reactive Forms are your answer. There is no perfect way to do what you want. But I picked out a particular piece of an example from an old project. So, on one point I check for the type of comparators I have available due to my first choice. After that I check if I need a field that requires a simple input field or a datepicker. There are SO many ways to do this.

<div class="col-7">
    <!-- Text Input Field for most cases that don't involve time comparisons -->
    <div *ngIf="!doesRequireDateInput(i) && checkIfComparatorOptionIsEmptyOrNull(i)">
        <div class="string-input-field" formArrayName="values">
            <div [formGroupName]="j" *ngFor="let val of getValues(condition); let j = index">

                <div class="input-group">
                    <input formControlName="value" type="text" class="form-control py-0" placeholder="Search for...">
                </div>
            </div>
        </div>
    </div>

    <!-- Date Input Field -->
    <div *ngIf="doesRequireDateInput(i) && checkIfComparatorOptionIsEmptyOrNull(i)">
        <div class="string-input-field row" formArrayName="values">
            <div [formGroupName]="j" *ngFor="let val of getValues(condition); let j = index">

                <div *ngIf="j === 0" class="input-group mb-3">
                    <input type="text" formControlName="value" name="dateFrom" class="form-control py-0" style="text-align: center" [owlDateTimeTrigger]="dt3"
                     [owlDateTime]="dt3">
                    <owl-date-time [pickerType]="'calendar'" #dt3></owl-date-time>


                    <div class="input-group-append">
                        <span class="input-group-text" style="border-bottom-right-radius: 0px; border-top-right-radius: 0px" id="date-for-input">
                            <i class="fa fa-calendar" aria-hidden="true"></i>
                        </span>
                    </div>
                </div>

                <div *ngIf="j === 1" class="input-group mb-3">
                    <input type="text" formControlName="value" name="dateFrom" class="form-control py-0" style="text-align: center" [owlDateTimeTrigger]="dt3"
                     [owlDateTime]="dt3">
                    <owl-date-time [pickerType]="'calendar'" #dt3></owl-date-time>
                </div>
            </div>
        </div>
    </div>
</div>