PrimeNG P-Dropdown Stretch 100%

In my case I used autoWidth = false and set style attrribute like below

<p-dropdown [options]="educationLevels" [(ngModel)]="selectedEducationLevel" 
name="educationlevel" autoWidth="false" [style]="{'width':'100%'}"></p-dropdown>

I found to use the Responsive approach and apply .ui-fluid style with Grid CSS at container while p-dropdown should have the [autoWidth]="false" attribute.

Example:

<div class="ui-grid ui-grid-responsive ui-fluid">
    <div class="ui-grid-row">
        <div class="ui-grid-col-12">
            <p-dropdown [autoWidth]="false"></p-dropdown>
        </div>
    </div>
</div>

For me,

[style]="{'minWidth':'100%'}"

does the trick!

Then I used like this:

<span style="width: 100%">
   <p-dropdown [style]="{'minWidth':'100%'}" [options]="items" [(ngModel)]="selecteditem"></p-dropdown>
</span>

You can try this

html:

<div class="p-col-10">
  <span class="p-fluid">
    <p-dropdown></p-dropdown>
  </span>
</div>

css:

.p-dropdown-panel {
  left: 0 !important;
  max-width: 100% !important;
}
.p-autocomplete-panel .p-autocomplete-items .p-autocomplete-item {
  white-space: inherit;
}

The [autoWidth] attr was removed in v7 but I was able to achieve this with >7 version using styleClass="w-100": <p-dropdown styleClass="w-100" ...>

You should be writing in a css file using the mentioned class as below,

.ui-dropdown    {
  width:100% !important;
}

Set it to be !important

LIVE DEMO

You should be editing a class in a primeng.min.css file as below,

.ui-dropdown .ui-dropdown-panel {
  min-width: 100%;
  width: max-content;
}

<p-dropdown id="id" [options]="list"></p-dropdown>

then Dropdownlist should take size of biggest option.

For me:

.ui-dropdown {
  max-width: 100%;
}

Did the trick, here is my html:

<p-dropdown
  [options]="sitBusinessPartner"
  [filter]="true"
  [(ngModel)]="businessPartner"
  (onChange)="changeBusinessPartner()"
  [autoWidth]="false"
></p-dropdown>

Edit, I suggest to use this:

.ui-dropdown.ui-dropdown-clearable .ui-dropdown-label {
  text-overflow: ellipsis;
}

.ui-dropdown .ui-dropdown-label {
  text-overflow: ellipsis;
}

In order to handle a possible text overflow and display a nice ellipsis like this:

This solution was adapted from here.

What I did and worked for me:

Using the grid system you can choose how many "columns" to display the element. For example, if you want to stretch 100% inside the container, consider that the element is occupying 12 columns, like in the code below:

<div class="p-formgrid p-grid">
        <div class="p-field p-col">
            <p-dropdown></p-dropdown>
        </div>
</div>

But let's say you want to put another element next to it and want them to have the same width, you'd have something like that:

<div class="p-formgrid p-grid">
        <div class="p-field p-col">
            <p-dropdown></p-dropdown>
        </div>
        <div class="p-field p-col">
            <element></element>
        </div>
</div>

You can also have different widths for each element, based on how many columns they are occupying:

<div class="p-formgrid p-grid">
        <div class="p-field p-col-7">
            <p-dropdown></p-dropdown>
        </div>
        <div class="p-field p-col">
            <element></element>
        </div>
</div>

The sum of the columns has to be 12. If you said the first element is 7 columns long, the second will get 5 columns automatically. Try different values and see what works best for you.

For me, using prime-ng dropdown with template in grid, container that hold p-dropdown was flex so this both combined worked [className]="'col-12 p-0'" and [styleClass]="'col-12 p-0'" added into p-dropdown tag

"autoWidth" did not work for me, I just did this in my CSS:

p-dropdown {
    min-width: 80%;
}
.ui-dropdown{
    width: 100%;
}

Try this in css file.

:host ::ng-deep .p-dropdown {
    width: 100%;
}

Use :host and ::ng-deep in your component css or scss file:

:host ::ng-deep.p-dropdown {
    width: 255px !important;
    height: 28px !important;
}