Autocomplete

The Autocomplete component offers simple and flexible type-ahead functionality. It is great for searching a value from a long list of options. In comparison to a Select, the Autocomplete doesn't need to know the complete item list, it only calls a search function which will return matching items. The search function can even run asynchronously, i.e. for database queries.

Usage

How you write the search function determines whether or not the Autocomplete shows a full list initially. By setting ResetValueOnEmptyText="true", the Value will be reset when the user clears the input text. With CoerceText="true" upon selection of an entry from the list, the Text is always updated. When the user types something that is not on the list and CoerceValue is true, the Value will be overwritten with the user input which allows it to be passed to the validation function.

Not selected
Not selected

@using System.Threading

<MudGrid>
    <MudItem xs="12" sm="6" md="4">
        <MudAutocomplete T="string" Label="US States" @bind-Value="value1" SearchFunc="@Search1"
                         ResetValueOnEmptyText="@resetValueOnEmptyText"
                         CoerceText="@coerceText" CoerceValue="@coerceValue" />
    </MudItem>
    <MudItem xs="12" sm="6" md="4">
        <MudAutocomplete T="string" Label="US States" @bind-Value="value2" SearchFunc="@Search2"
                         ResetValueOnEmptyText="@resetValueOnEmptyText"
                         CoerceText="@coerceText" CoerceValue="@coerceValue"
                         AdornmentIcon="@Icons.Material.Filled.Search" AdornmentColor="Color.Primary" />
    </MudItem>
    <MudItem xs="12" md="12">
        <MudText Class="mb-n3" Typo="Typo.body2">
            <MudChip T="string">@(value1 ?? "Not selected")</MudChip><MudChip T="string">@(value2 ?? "Not selected")</MudChip>
        </MudText>
    </MudItem>
    <MudItem xs="12" md="12" class="flex-column">
        <MudSwitch @bind-Value="resetValueOnEmptyText" Color="Color.Primary">Reset Value on empty Text</MudSwitch>
        <MudSwitch @bind-Value="coerceText" Color="Color.Secondary">Coerce Text to Value</MudSwitch>
        <MudSwitch @bind-Value="coerceValue" Color="Color.Tertiary">Coerce Value to Text (if not found)</MudSwitch>
    </MudItem>
</MudGrid>
@code {
    private bool resetValueOnEmptyText;
    private bool coerceText;
    private bool coerceValue;
    private string value1, value2;
    private string[] states =
    {
        "Alabama", "Alaska", "American Samoa", "Arizona",
        "Arkansas", "California", "Colorado", "Connecticut",
        "Delaware", "District of Columbia", "Federated States of Micronesia",
        "Florida", "Georgia", "Guam", "Hawaii", "Idaho",
        "Illinois", "Indiana", "Iowa", "Kansas", "Kentucky",
        "Louisiana", "Maine", "Marshall Islands", "Maryland",
        "Massachusetts", "Michigan", "Minnesota", "Mississippi",
        "Missouri", "Montana", "Nebraska", "Nevada",
        "New Hampshire", "New Jersey", "New Mexico", "New York",
        "North Carolina", "North Dakota", "Northern Mariana Islands", "Ohio",
        "Oklahoma", "Oregon", "Palau", "Pennsylvania", "Puerto Rico",
        "Rhode Island", "South Carolina", "South Dakota", "Tennessee",
        "Texas", "Utah", "Vermont", "Virgin Island", "Virginia",
        "Washington", "West Virginia", "Wisconsin", "Wyoming",
    };

    private async Task<IEnumerable<string>> Search1(string value, CancellationToken token)
    {
        // In real life use an asynchronous function for fetching data from an api.
        await Task.Delay(5, token);

        // if text is null or empty, show complete list
        if (string.IsNullOrEmpty(value))
            return states;
        return states.Where(x => x.Contains(value, StringComparison.InvariantCultureIgnoreCase));
    }

    private async Task<IEnumerable<string>> Search2(string value, CancellationToken token)
    {
        // In real life use an asynchronous function for fetching data from an api.
        await Task.Delay(5, token);

        // if text is null or empty, don't return values (drop-down will not open)
        if (string.IsNullOrEmpty(value))
            return new string[0];
        return states.Where(x => x.Contains(value, StringComparison.InvariantCultureIgnoreCase));
    }
}
Margin And Dense

While the margin property affects the input element, the dense property affects the dropdown element.

@using System.Threading

<MudGrid>
    <MudItem xs="12" sm="6">
        <div>
            <MudCheckBox T="bool" ValueChanged="ChangeMargin" Color="Color.Primary" Label="@(" Margin: " + _margin)" />
        </div>
        <div>
            <MudCheckBox @bind-Value="_dense" Color="Color.Primary" Label="@(" Dense: " + _dense)" />
        </div>
    </MudItem>
    <MudItem xs="12" sm="6" md="4">
        <MudAutocomplete T="string" Label="US States" @bind-Value="value1" SearchFunc="@Search1" Margin="@_margin" Dense="@_dense" Variant="Variant.Outlined" />
    </MudItem>
</MudGrid>
@code {
    Margin _margin = Margin.None;
    bool _dense = false;

    private void ChangeMargin()
    {
        if (_margin == Margin.None)
        {
            _margin = Margin.Dense;
        }
        else
        {
            _margin = Margin.None;
        }
    }

    private string value1;
    private string[] states =
    {
        "Alabama", "Alaska", "American Samoa", "Arizona",
        "Arkansas", "California", "Colorado", "Connecticut",
        "Delaware", "District of Columbia", "Federated States of Micronesia",
        "Florida", "Georgia", "Guam", "Hawaii", "Idaho",
        "Illinois", "Indiana", "Iowa", "Kansas", "Kentucky",
        "Louisiana", "Maine", "Marshall Islands", "Maryland",
        "Massachusetts", "Michigan", "Minnesota", "Mississippi",
        "Missouri", "Montana", "Nebraska", "Nevada",
        "New Hampshire", "New Jersey", "New Mexico", "New York",
        "North Carolina", "North Dakota", "Northern Mariana Islands", "Ohio",
        "Oklahoma", "Oregon", "Palau", "Pennsylvania", "Puerto Rico",
        "Rhode Island", "South Carolina", "South Dakota", "Tennessee",
        "Texas", "Utah", "Vermont", "Virgin Island", "Virginia",
        "Washington", "West Virginia", "Wisconsin", "Wyoming",
    };

    private async Task<IEnumerable<string>> Search1(string value, CancellationToken token)
    {
        // In real life use an asynchronous function for fetching data from an api.
        await Task.Delay(5, token);

        // if text is null or empty, show complete list
        if (string.IsNullOrEmpty(value))
            return states;
        return states.Where(x => x.Contains(value, StringComparison.InvariantCultureIgnoreCase));
    }
}
Presentation

When you use objects, Autocomplete uses ToString() to convert the object into text form. You can set a custom ToStringFunc to override how the list items are stringified. This string representation is also what you'll get as input to the search function.
If that is not enough, you can define an <ItemTemplate> and even an <ItemSelectedTemplate> to create highly sophisticated list item presentations.

Selected values:

Not selected
Not selected

@using System.Net.Http.Json
@using MudBlazor.Examples.Data.Models
@using System.Threading
@inject HttpClient httpClient

<MudGrid>
    <MudItem xs="12" sm="6" md="4">
        <MudAutocomplete T="Element" Label="Periodic Table Element" @bind-Value="value1" 
                         SearchFunc="@Search" ToStringFunc="@(e=> e==null?null : $"{e.Name} ({e.Sign})")" />
    </MudItem>
    <MudItem xs="12" sm="6" md="4">
        <MudAutocomplete T="Element" Label="Periodic Table Element" @bind-Value="value2" 
                         SearchFunc="@Search" ToStringFunc="@(e=> e==null?null : $"{e.Name} ({e.Sign})")">
            <ItemTemplate Context="e">                          
                <MudText>
                    <MudIcon Icon="@Icons.Material.Filled.CheckBoxOutlineBlank" Class="mb-n1 mr-3"/>@($"{e.Name} ({e.Sign})")
                </MudText>
            </ItemTemplate>
            <ItemSelectedTemplate Context="e">                
                <MudText>
                    <MudIcon Icon="@Icons.Material.Filled.CheckBox" Class="mb-n1 mr-3"/>@($"{e.Name} ({e.Sign})")
                </MudText>
            </ItemSelectedTemplate>
        </MudAutocomplete>
    </MudItem>
    <MudItem xs="12" md="12">
        <MudText Class="mb-n3" Typo="Typo.body2">
            Selected values: <MudChip T="string">@(value1?.ToString() ?? "Not selected")</MudChip><MudChip T="string">@(value2?.ToString() ?? "Not selected")</MudChip>
        </MudText>
    </MudItem>
</MudGrid>
@code {
    private Element value1, value2;

    private async Task<IEnumerable<Element>> Search(string value, CancellationToken token)
    {
        return  await httpClient.GetFromJsonAsync<List<Element>>($"webapi/periodictable/{value}", token);
    }
}

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