Create a search app in ASP.NET Core

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08/28/2024

In this tutorial, create a basic ASP.NET Core (Model-View-Controller) app that runs in localhost and connects to the hotels-sample-index on your search service. In this tutorial, learn how to:

Create a basic search page
Filter results
Sort results

This tutorial puts the focus on server-side operations called through the Search APIs. Although it's common to sort and filter in client-side script, knowing how to invoke these operations on the server gives you more options when designing the search experience.

Sample code for this tutorial can be found in the azure-search-dotnet-samples repository on GitHub.

Prerequisites

Visual Studio
Azure.Search.Documents NuGet package
Azure AI Search, any tier, but it must have public network access.
Hotel samples index

Step through the Import data wizard to create the hotels-sample-index on your search service. Or, change the index name in the HomeController.cs file.

Create the project

Start Visual Studio and select Create a new project.
Select ASP.NET Core Web App (Model-View-Controller), and then select Next.
Provide a project name, and then select Next.
On the next page, select .NET 6.0 or .NET 7.0 or .NET 8.0.
Verify that Do not use top-level statements is unchecked.
Select Create.

Add NuGet packages

On Tools, select NuGet Package Manager > Manage NuGet Packages for the solution.
Browse for Azure.Search.Documents and install the latest stable version.
Browse for and install the Microsoft.Spatial package. The sample index includes a GeographyPoint data type. Installing this package avoids run time errors. Alternatively, remove the "Location" field from the Hotels class if you don't want to install the package. That field isn't used in this tutorial.

Add service information

For the connection, the app presents a query API key to your fully qualified search URL. Both are specified in the appsettings.json file.

Modify appsettings.json to specify your search service and query API key.

{
    "SearchServiceUri": "<YOUR-SEARCH-SERVICE-URL>",
    "SearchServiceQueryApiKey": "<YOUR-SEARCH-SERVICE-QUERY-API-KEY>"
}

You can get the service URL and API key from the portal. Because this code is querying an index and not creating one, you can use a query key instead of an admin key.

Make sure to specify the search service that has the hotels-sample-index.

Add models

In this step, create models that represent the schema of the hotels-sample-index.

In Solution explorer, right-select Models and add a new class named "Hotel" for the following code:

 using Azure.Search.Documents.Indexes.Models;
 using Azure.Search.Documents.Indexes;
 using Microsoft.Spatial;
 using System.Text.Json.Serialization;

 namespace HotelDemoApp.Models
 {
     public partial class Hotel
     {
         [SimpleField(IsFilterable = true, IsKey = true)]
         public string HotelId { get; set; }

         [SearchableField(IsSortable = true)]
         public string HotelName { get; set; }

         [SearchableField(AnalyzerName = LexicalAnalyzerName.Values.EnLucene)]
         public string Description { get; set; }

         [SearchableField(AnalyzerName = LexicalAnalyzerName.Values.FrLucene)]
         [JsonPropertyName("Description_fr")]
         public string DescriptionFr { get; set; }

         [SearchableField(IsFilterable = true, IsSortable = true, IsFacetable = true)]
         public string Category { get; set; }

         [SearchableField(IsFilterable = true, IsFacetable = true)]
         public string[] Tags { get; set; }

         [SimpleField(IsFilterable = true, IsSortable = true, IsFacetable = true)]
         public bool? ParkingIncluded { get; set; }

         [SimpleField(IsFilterable = true, IsSortable = true, IsFacetable = true)]
         public DateTimeOffset? LastRenovationDate { get; set; }

         [SimpleField(IsFilterable = true, IsSortable = true, IsFacetable = true)]
         public double? Rating { get; set; }

         public Address Address { get; set; }

         [SimpleField(IsFilterable = true, IsSortable = true)]
         public GeographyPoint Location { get; set; }

         public Rooms[] Rooms { get; set; }
     }
 }

Add a class named "Address" and replace it with the following code:

 using Azure.Search.Documents.Indexes;

 namespace HotelDemoApp.Models
 {
     public partial class Address
     {
         [SearchableField]
         public string StreetAddress { get; set; }

         [SearchableField(IsFilterable = true, IsSortable = true, IsFacetable = true)]
         public string City { get; set; }

         [SearchableField(IsFilterable = true, IsSortable = true, IsFacetable = true)]
         public string StateProvince { get; set; }

         [SearchableField(IsFilterable = true, IsSortable = true, IsFacetable = true)]
         public string PostalCode { get; set; }

         [SearchableField(IsFilterable = true, IsSortable = true, IsFacetable = true)]
         public string Country { get; set; }
     }
 }

Add a class named "Rooms" and replace it with the following code:

 using Azure.Search.Documents.Indexes.Models;
 using Azure.Search.Documents.Indexes;
 using System.Text.Json.Serialization;

 namespace HotelDemoApp.Models
 {
     public partial class Rooms
     {
         [SearchableField(AnalyzerName = LexicalAnalyzerName.Values.EnMicrosoft)]
         public string Description { get; set; }

         [SearchableField(AnalyzerName = LexicalAnalyzerName.Values.FrMicrosoft)]
         [JsonPropertyName("Description_fr")]
         public string DescriptionFr { get; set; }

         [SearchableField(IsFilterable = true, IsFacetable = true)]
         public string Type { get; set; }

         [SimpleField(IsFilterable = true, IsFacetable = true)]
         public double? BaseRate { get; set; }

         [SearchableField(IsFilterable = true, IsFacetable = true)]
         public string BedOptions { get; set; }

         [SimpleField(IsFilterable = true, IsFacetable = true)]
         public int SleepsCount { get; set; }

         [SimpleField(IsFilterable = true, IsFacetable = true)]
         public bool? SmokingAllowed { get; set; }

         [SearchableField(IsFilterable = true, IsFacetable = true)]
         public string[] Tags { get; set; }
     }
 }

Add a class named "SearchData" and replace it with the following code:

 using Azure.Search.Documents.Models;

 namespace HotelDemoApp.Models
 {
     public class SearchData
     {
         // The text to search for.
         public string searchText { get; set; }

         // The list of results.
         public SearchResults<Hotel> resultList;
     }
 }

Modify the controller

For this tutorial, modify the default HomeController to contain methods that execute on your search service.

In Solution explorer under Models, open HomeController.

Replace the default with the following content:

using Azure;
 using Azure.Search.Documents;
 using Azure.Search.Documents.Indexes;
 using HotelDemoApp.Models;
 using Microsoft.AspNetCore.Mvc;
 using System.Diagnostics;

 namespace HotelDemoApp.Controllers
 {
     public class HomeController : Controller
     {
         public IActionResult Index()
         {
             return View();
         }

         [HttpPost]
         public async Task<ActionResult> Index(SearchData model)
         {
             try
             {
                 // Check for a search string
                 if (model.searchText == null)
                 {
                     model.searchText = "";
                 }

                 // Send the query to Search.
                 await RunQueryAsync(model);
             }

             catch
             {
                 return View("Error", new ErrorViewModel { RequestId = "1" });
             }
             return View(model);
         }

         [ResponseCache(Duration = 0, Location = ResponseCacheLocation.None, NoStore = true)]
         public IActionResult Error()
         {
             return View(new ErrorViewModel { RequestId = Activity.Current?.Id ?? HttpContext.TraceIdentifier });
         }

         private static SearchClient _searchClient;
         private static SearchIndexClient _indexClient;
         private static IConfigurationBuilder _builder;
         private static IConfigurationRoot _configuration;

         private void InitSearch()
         {
             // Create a configuration using appsettings.json
             _builder = new ConfigurationBuilder().AddJsonFile("appsettings.json");
             _configuration = _builder.Build();

             // Read the values from appsettings.json
             string searchServiceUri = _configuration["SearchServiceUri"];
             string queryApiKey = _configuration["SearchServiceQueryApiKey"];

             // Create a service and index client.
             _indexClient = new SearchIndexClient(new Uri(searchServiceUri), new AzureKeyCredential(queryApiKey));
             _searchClient = _indexClient.GetSearchClient("hotels-sample-index");
         }

         private async Task<ActionResult> RunQueryAsync(SearchData model)
         {
             InitSearch();

             var options = new SearchOptions()
             {
                 IncludeTotalCount = true
             };

             // Enter Hotel property names to specify which fields are returned.
             // If Select is empty, all "retrievable" fields are returned.
             options.Select.Add("HotelName");
             options.Select.Add("Category");
             options.Select.Add("Rating");
             options.Select.Add("Tags");
             options.Select.Add("Address/City");
             options.Select.Add("Address/StateProvince");
             options.Select.Add("Description");

             // For efficiency, the search call should be asynchronous, so use SearchAsync rather than Search.
             model.resultList = await _searchClient.SearchAsync<Hotel>(model.searchText, options).ConfigureAwait(false);

             // Display the results.
             return View("Index", model);
         }
         public IActionResult Privacy()
         {
             return View();
         }
     }
 }

Modify the view

In Solution explorer under Views > Home, open index.cshtml.

Replace the default with the following content:

@model HotelDemoApp.Models.SearchData;

@{
    ViewData["Title"] = "Index";
}

<div>
    <h2>Search for Hotels</h2>

    <p>Use this demo app to test server-side sorting and filtering. Modify the RunQueryAsync method to change the operation. The app uses the default search configuration (simple search syntax, with searchMode=Any).</p>

    <form asp-controller="Home" asp-action="Index">
        <p>
            <input type="text" name="searchText" />
            <input type="submit" value="Search" />
        </p>
    </form>
</div>

<div>
    @using (Html.BeginForm("Index", "Home", FormMethod.Post))
    {
        @if (Model != null)
        {
            // Show the result count.
            <p>@Model.resultList.TotalCount Results</p>

            // Get search results.
            var results = Model.resultList.GetResults().ToList();

            {
                <table class="table">
                    <thead>
                        <tr>
                            <th>Name</th>
                            <th>Category</th>
                            <th>Rating</th>
                            <th>Tags</th>
                            <th>City</th>
                            <th>State</th>
                            <th>Description</th>
                        </tr>
                    </thead>
                    <tbody>
                        @foreach (var d in results)
                        {
                            <tr>
                                <td>@d.Document.HotelName</td>
                                <td>@d.Document.Category</td>
                                <td>@d.Document.Rating</td>
                                <td>@d.Document.Tags[0]</td>
                                <td>@d.Document.Address.City</td>
                                <td>@d.Document.Address.StateProvince</td>
                                <td>@d.Document.Description</td>
                            </tr>
                        }
                    </tbody>
                  </table>
            }
        }
    }
</div>

Run the sample

Press F5 to compile and run the project. The app runs on local host and opens in your default browser.
Select Search to return all results.
This code uses the default search configuration, supporting the simple syntax and searchMode=Any. You can enter keywords, augment with Boolean operators, or run a prefix search (pool*).

In the next several sections, modify the RunQueryAsync method in the HomeController to add filters and sorting.

Filter results

Index field attributes determine which fields are searchable, filterable, sortable, facetable, and retrievable. In the hotels-sample-index, filterable fields include Category, Address/City, and Address/StateProvince. This example adds a $Filter expression on Category.

A filter always executes first, followed by a query assuming one is specified.

Open the HomeController and find the RunQueryAsync method. Add Filter to var options = new SearchOptions():

 private async Task<ActionResult> RunQueryAsync(SearchData model)
 {
     InitSearch();

     var options = new SearchOptions()
     {
         IncludeTotalCount = true,
         Filter = "search.in(Category,'Budget,Suite')"
     };

     options.Select.Add("HotelName");
     options.Select.Add("Category");
     options.Select.Add("Rating");
     options.Select.Add("Tags");
     options.Select.Add("Address/City");
     options.Select.Add("Address/StateProvince");
     options.Select.Add("Description");

     model.resultList = await _searchClient.SearchAsync<Hotel>(model.searchText, options).ConfigureAwait(false);

     return View("Index", model);
 }

Run the application.
Select Search to run an empty query. The filter returns 18 documents instead of the original 50.

For more information about filter expressions, see Filters in Azure AI Search and OData $filter syntax in Azure AI Search.

Sort results

In the hotels-sample-index, sortable fields include Rating and LastRenovated. This example adds an $OrderBy expression to the Rating field.

Open the HomeController and replace RunQueryAsync method with the following version:

 private async Task<ActionResult> RunQueryAsync(SearchData model)
 {
     InitSearch();

     var options = new SearchOptions()
     {
         IncludeTotalCount = true,
     };

     options.OrderBy.Add("Rating desc");

     options.Select.Add("HotelName");
     options.Select.Add("Category");
     options.Select.Add("Rating");
     options.Select.Add("Tags");
     options.Select.Add("Address/City");
     options.Select.Add("Address/StateProvince");
     options.Select.Add("Description");

     model.resultList = await _searchClient.SearchAsync<Hotel>(model.searchText, options).ConfigureAwait(false);

     return View("Index", model);
 }

Run the application. Results are sorted by Rating in descending order.

For more information about sorting, see OData $orderby syntax in Azure AI Search.

Next steps

In this tutorial, you created an ASP.NET Core (MVC) project that connected to a search service and called Search APIs for server-side filtering and sorting.

If you want to explore client-side code that responds to user actions, consider adding a React template to your solution:

C# Tutorial: Add search to a website with .NET

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