<mat-select> is a form control for selecting a value from a set of options, similar to the native
<select> element. You can read more about selects in the
Material Design spec. It is designed to work
inside of a <mat-form-field>
element.
To add options to the select, add <mat-option> elements to the <mat-select>. Each <mat-option>
has a value property that can be used to set the value that will be selected if the user chooses
this option. The content of the <mat-option> is what will be shown to the user.
Angular Material also supports use of the native <select> element inside of
<mat-form-field>. The native control has several performance, accessibility,
and usability advantages. See the documentation for
form-field for more information.
To use a native select inside <mat-form-field>, add the matNativeControl attribute
to the <select> element.
The <mat-select> supports 2-way binding to the value property without the need for Angular
forms.
You selected: option2
Both<mat-select> and <select> support all of the form directives from the core FormsModule (NgModel) and
ReactiveFormsModule (FormControl, FormGroup, etc.) As with native <select>, <mat-select>
also supports a compareWith function. (Additional information about using a custom compareWith
function can be found in the
Angular forms documentation).
There are a number of <mat-form-field> features that can be used with both <select> and <mat-select>. These
include error messages, hint text, prefix & suffix, and theming. For additional information about
these features, see the
form field documentation.
The placeholder is text shown when the <mat-form-field> label is floating but the <mat-select>
is empty. It is used to give the user an additional hint about the value they should select. The
placeholder can be specified by setting the placeholder attribute on the <mat-select> element.
In some cases that <mat-form-field> may use the placeholder as the label (see the
form field label documentation).
It is possible to disable the entire select or individual options in the select by using the
disabled property on the <select> or <mat-select> and the <option> or
If you want one of your options to reset the select's value, you can omit specifying its value.
The <mat-optgroup> element can be used to group common options under a subheading. The name of the
group can be set using the label property of <mat-optgroup>. Like individual <mat-option>
elements, an entire <mat-optgroup> can be disabled or enabled by setting the disabled property
on the group.
<mat-select> defaults to single-selection mode, but can be configured to allow multiple selection
by setting the multiple property. This will allow the user to select multiple values at once. When
using the <mat-select> in multiple selection mode, its value will be a sorted list of all selected
values rather than a single value.
Using multiple selection with a native select element (<select multiple>) is discouraged
inside <mat-form-field>, as the inline listbox appearance is inconsistent with other
Material Design components.
If you want to display a custom trigger label inside a <mat-select>, you can use the
<mat-select-trigger> element.
By default, when a user clicks on a <mat-option>, a ripple animation is shown. This can be disabled
by setting the disableRipple property on <mat-select>.
In order to facilitate easily styling the dropdown panel, <mat-select> has a panelClass property
which can be used to apply additional CSS classes to the dropdown panel.
The <mat-form-field> allows you to
associate error messages
with your <select> or <mat-select>. By default, these error messages are shown when the control is invalid and
either the user has interacted with (touched) the element or the parent form has been submitted. If
you wish to override this behavior (e.g. to show the error as soon as the invalid control is dirty
or when a parent form group is invalid), you can use the errorStateMatcher property of the
<mat-select>. The property takes an instance of an ErrorStateMatcher object. An
ErrorStateMatcher must implement a single method isErrorState which takes the FormControl for
this <mat-select> as well as the parent form and returns a boolean indicating whether errors
should be shown. (true indicating that they should be shown, and false indicating that they
should not.)
A global error state matcher can be specified by setting the ErrorStateMatcher provider. This
applies to all inputs. For convenience, ShowOnDirtyErrorStateMatcher is available in order to
globally cause input errors to show when the input is dirty and invalid.
@NgModule({
providers: [
{provide: ErrorStateMatcher, useClass: ShowOnDirtyErrorStateMatcher}
]
})The <mat-select> component without text or label should be given a meaningful label via
aria-label or aria-labelledby.
The <mat-select> component has role="listbox" and options inside select have role="option".
The native <select> offers the best accessibility because it is supported directly by screen-readers.
multiple mode of select after initialization
This error is thrown if you attempt to bind the multiple property on <mat-select> to a dynamic
value. (e.g. [multiple]="isMultiple" where the value of isMultiple changes over the course of
the component's lifetime). If you need to change this dynamically, use ngIf or ngSwitch instead:
<mat-select *ngIf="isMultiple" multiple>
...
</mat-select>
<mat-select *ngIf="!isMultiple">
...
</mat-select>This error is thrown if you attempt to assign a value other than null, undefined, or an array to
a <mat-select multiple>. For example, something like mySelect.value = 'option1'. What you likely
meant to do was mySelect.value = ['option1'].
compareWith must be a function
This error occurs if you attempt to assign something other than a function to the compareWith
property. For more information on proper usage of compareWith see the
Angular forms documentation).