The autocomplete is a normal text input enhanced by a panel of suggested options.

Simple autocomplete

Start by creating the autocomplete panel and the options displayed inside it. Each option should be defined by a mat-option tag. Set each option's value property to whatever you'd like the value of the text input to be when that option is selected.

Next, create the input and set the matAutocomplete input to refer to the template reference we assigned to the autocomplete. Let's assume you're using the formControl directive from ReactiveFormsModule to track the value of the input.

Note: It is possible to use template-driven forms instead, if you prefer. We use reactive forms in this example because it makes subscribing to changes in the input's value easy. For this example, be sure to import ReactiveFormsModule from @angular/forms into your NgModule. If you are unfamiliar with using reactive forms, you can read more about the subject in the Angular documentation.

Now we'll need to link the text input to its panel. We can do this by exporting the autocomplete panel instance into a local template variable (here we called it "auto"), and binding that variable to the input's matAutocomplete property.

Adding a custom filter

At this point, the autocomplete panel should be toggleable on focus and options should be selectable. But if we want our options to filter when we type, we need to add a custom filter.

You can filter the options in any way you like based on the text input*. Here we will perform a simple string test on the option value to see if it matches the input value, starting from the option's first letter. We already have access to the built-in valueChanges Observable on the FormControl, so we can simply map the text input's values to the suggested options by passing them through this filter. The resulting Observable, filteredOptions, can be added to the template in place of the options property using the async pipe.

Below we are also priming our value change stream with an empty string so that the options are filtered by that value on init (before there are any value changes).

*For optimal accessibility, you may want to consider adding text guidance on the page to explain filter criteria. This is especially helpful for screenreader users if you're using a non-standard filter that doesn't limit matches to the beginning of the string.

Setting separate control and display values

If you want the option's control value (what is saved in the form) to be different than the option's display value (what is displayed in the text field), you'll need to set the displayWith property on your autocomplete element. A common use case for this might be if you want to save your data as an object, but display just one of the option's string properties.

To make this work, create a function on your component class that maps the control value to the desired display value. Then bind it to the autocomplete's displayWith property.

Require an option to be selected

By default, the autocomplete will accept the value that the user typed into the input field. Instead, if you want to instead ensure that an option from the autocomplete was selected, you can enable the requireSelection input on mat-autocomplete. This will change the behavior of the autocomplete in the following ways:

1. If the user opens the autocomplete, changes its value, but doesn't select anything, the autocomplete value will be reset back to null.
2. If the user opens and closes the autocomplete without changing the value, the old value will be preserved.

This behavior can be configured globally using the MAT_AUTOCOMPLETE_DEFAULT_OPTIONS injection token.

Automatically highlighting the first option

If your use case requires for the first autocomplete option to be highlighted when the user opens the panel, you can do so by setting the autoActiveFirstOption input on the mat-autocomplete component. This behavior can be configured globally using the MAT_AUTOCOMPLETE_DEFAULT_OPTIONS injection token.

Autocomplete on a custom input element

While mat-autocomplete supports attaching itself to a mat-form-field, you can also set it on any other input element using the matAutocomplete attribute. This allows you to customize what the input looks like without having to bring in the extra functionality from mat-form-field.

Attaching the autocomplete panel to a different element

By default the autocomplete panel will be attached to your input element, however in some cases you may want it to attach to a different container element. You can change the element that the autocomplete is attached to using the matAutocompleteOrigin directive together with the matAutocompleteConnectedTo input:

<div class="custom-wrapper-example" matAutocompleteOrigin #origin="matAutocompleteOrigin">
  <input
    matInput
    [formControl]="myControl"
    [matAutocomplete]="auto"
    [matAutocompleteConnectedTo]="origin">
</div>

<mat-autocomplete #auto="matAutocomplete">
  <mat-option *ngFor="let option of options" [value]="option">{{option}}</mat-option>
</mat-autocomplete>

Keyboard interaction

Keyboard shortcut	Action
Down Arrow	Navigate to the next option.
Up Arrow	Navigate to the previous option.
Enter	Select the active option.
Escape	Close the autocomplete panel.
Alt + Up Arrow	Close the autocomplete panel.
Alt + Down Arrow	Open the autocomplete panel if there are any matching options.

Option groups

mat-option can be collected into groups using the mat-optgroup element:

Accessibility

MatAutocomplete implements the ARIA combobox interaction pattern. The text input trigger specifies role="combobox" while the content of the pop-up applies role="listbox". Because of this listbox pattern, you should not put other interactive controls, such as buttons or checkboxes, inside an autocomplete option. Nesting interactive controls like this interferes with most assistive technology.

Always provide an accessible label for the autocomplete. This can be done by using a <mat-label> inside of <mat-form-field>, a native <label> element, the aria-label attribute, or the aria-labelledby attribute.

MatAutocomplete preserves focus on the text trigger, using aria-activedescendant to support navigation though the autocomplete options.

By default, MatAutocomplete displays a checkmark to identify the selected item. While you can hide the checkmark indicator via hideSingleSelectionIndicator, this makes the component less accessible by making it harder or impossible for users to visually identify selected items.