Explore Azure AI Search query integration in a C# app

In the previous step, you deployed the search-enabled website to Azure Container Apps. This article highlights the essential steps that establish search integration. Think of it as a cheat sheet for integrating search into your web app.

Azure SDK Azure.Search.Documents

The API uses the Azure SDK for Azure AI Search:

• NuGet: Azure.Search.Documents
• Reference documentation: Client Library

The API authenticates through the SDK to the cloud-based Azure AI Search API by using the search service name and index name. In Azure Container Apps, the container environment provides the configuration values. Managed identity is the default credential path.

Managed identity authentication

Each Azure function in the API creates its SearchClient through a shared SearchClientFactory class, so every function authenticates the same way. By default, the factory builds a DefaultAzureCredential and uses it to request tokens for Azure AI Search. In Azure Container Apps, DefaultAzureCredential resolves to the managed identity assigned to the container app.

The following method from SearchClientFactory.cs creates that credential. When the container app has a user-assigned managed identity, the client ID from the AZURE_CLIENT_ID environment variable is passed to DefaultAzureCredentialOptions so token acquisition isn't ambiguous.

private static DefaultAzureCredential CreateManagedIdentityCredential()
{
    var options = new DefaultAzureCredentialOptions();

    if (!string.IsNullOrWhiteSpace(ManagedIdentityClientId))
    {
        options.ManagedIdentityClientId = ManagedIdentityClientId;
    }

    return new DefaultAzureCredential(options);
}

The Bicep infrastructure assigns the managed identity access to the Azure AI Search data plane during azd up. This role assignment lets the API query the good-books index without storing a query key in the container environment.

Local vs. deployed credential resolution

Locally, if AZURE_CLIENT_ID is unset, DefaultAzureCredential falls back through its standard credential chain and resolves to your signed-in developer credential, such as the Azure CLI or Visual Studio Code account you used to sign in. When deployed to Azure Container Apps, the Bicep infrastructure sets AZURE_CLIENT_ID to the user-assigned managed identity's client ID, so DefaultAzureCredential targets that identity specifically instead of resolving ambiguously among multiple identities that a host can expose.

To use API keys instead, set USE_KEYLESS_AUTH to false before deployment:

azd env set USE_KEYLESS_AUTH false
azd up

Use key authentication only when your environment requires it.

Local development settings

For local development, the sample sample.local.settings.json file shows the values the API expects. Use local settings for development only. In Azure Container Apps, deployment configuration provides the equivalent container environment values.

{
  "IsEncrypted": false,
  "Values": {
    "AzureWebJobsStorage": "",
    "FUNCTIONS_WORKER_RUNTIME": "dotnet-isolated",
    "SearchServiceName": "",
    "SearchIndexName": "good-books"
  },
  "Host": {
    "CORS": "*"
  }
}

Function: Search the catalog

The Search API takes a search term and searches across the documents in the search index, returning a list of matches. Through the Suggest API, partial strings are sent to the search engine as the user types. The API suggests search terms, such as book titles and authors, based on documents in the search index and returns a small list of matches.

The Azure function pulls in the search configuration information from the container environment, creates the Azure AI Search client, and fulfills the query.

The search suggester, sg, is defined in the schema file used during bulk upload.

using Azure;
using Azure.Core.Serialization;
using Azure.Identity;
using Azure.Search.Documents;
using Azure.Search.Documents.Models;
using Microsoft.Azure.Functions.Worker;
using Microsoft.Azure.Functions.Worker.Http;
using Microsoft.Extensions.Logging;
using System.Net;
using System.Text.Json;
using System.Text.Json.Serialization;
using WebSearch.Models;
using SearchFilter = WebSearch.Models.SearchFilter;

namespace WebSearch.Function
{
    public class Search
    {
        private readonly ILogger<Lookup> _logger;

        public Search(ILogger<Lookup> logger)
        {
            _logger = logger;
        }

        [Function("search")]
        public async Task<HttpResponseData> RunAsync(
            [HttpTrigger(AuthorizationLevel.Anonymous, "post")] HttpRequestData req, 
            FunctionContext executionContext)
        {
            string requestBody = await new StreamReader(req.Body).ReadToEndAsync();
            var data = JsonSerializer.Deserialize<RequestBodySearch>(requestBody);

            // Azure AI Search (managed identity by default; API key only when SEARCH_USE_KEY_AUTH=true)
            SearchClient searchClient = SearchClientFactory.CreateSearchClient();

            SearchOptions options = new()

            {
                Size = data.Size,
                Skip = data.Skip,
                IncludeTotalCount = true,
                Filter = CreateFilterExpression(data.Filters)
            };
            options.Facets.Add("authors");
            options.Facets.Add("language_code");

            SearchResults<SearchDocument> searchResults = searchClient.Search<SearchDocument>(data.SearchText, options);

            var facetOutput = new Dictionary<string, IList<FacetValue>>();
            foreach (var facetResult in searchResults.Facets)
            {
                facetOutput[facetResult.Key] = facetResult.Value
                           .Select(x => new FacetValue { value = x.Value.ToString(), count = x.Count })

                           .ToList();
            }

            // Data to return 
            var output = new SearchOutput
            {
                Count = searchResults.TotalCount,
                Results = searchResults.GetResults().ToList(),
                Facets = facetOutput
            };
            
            var response = req.CreateResponse(HttpStatusCode.Found);

            // Serialize data
            var serializer = new JsonObjectSerializer(
                new JsonSerializerOptions(JsonSerializerDefaults.Web));
            await response.WriteAsJsonAsync(output, serializer);

            return response;
        }

        public static string CreateFilterExpression(List<SearchFilter> filters)
        {
            if (filters is null or { Count: <= 0 })
            {
                return null;
            }

            List<string> filterExpressions = new();


            List<SearchFilter> authorFilters = filters.Where(f => f.field == "authors").ToList();
            List<SearchFilter> languageFilters = filters.Where(f => f.field == "language_code").ToList();

            List<string> authorFilterValues = authorFilters.Select(f => f.value).ToList();

            if (authorFilterValues.Count > 0)
            {
                string filterStr = string.Join(",", authorFilterValues);
                filterExpressions.Add($"{"authors"}/any(t: search.in(t, '{filterStr}', ','))");
            }

            List<string> languageFilterValues = languageFilters.Select(f => f.value).ToList();
            foreach (var value in languageFilterValues)
            {
                filterExpressions.Add($"language_code eq '{value}'");
            }

            return string.Join(" and ", filterExpressions);
        }
    }
}

To verify the function independently, call /api/search with a search term in the request body and confirm the response includes matching book documents, a total count, and facet values.

Client: Search the catalog

The React client's Search page calls the search Azure function whenever the user enters a query, changes a facet filter, or moves to a new page of results. The client sends the search text, the current page's skip and top values, and any selected author or language filters in the POST body to /api/search. The function returns a list of matching book documents, a total count, and facet values, which the page uses to render the result list, pager, and facet filters. The following code in \client\src\pages\Search\Search.jsx builds that request and stores the response in component state:

import React, { useEffect, useState, Suspense } from 'react';
import fetchInstance from '../../url-fetch';
import CircularProgress from '@mui/material/CircularProgress';
import { useLocation, useNavigate } from "react-router-dom";

import Results from '../../components/Results/Results';
import Pager from '../../components/Pager/Pager';
import Facets from '../../components/Facets/Facets';
import SearchBar from '../../components/SearchBar/SearchBar';

import "./Search.css";

export default function Search() {

  let location = useLocation();
  const navigate = useNavigate();

  const [results, setResults] = useState([]);
  const [resultCount, setResultCount] = useState(0);
  const [currentPage, setCurrentPage] = useState(1);
  const [q, setQ] = useState(new URLSearchParams(location.search).get('q') ?? "*");
  const [top] = useState(new URLSearchParams(location.search).get('top') ?? 8);
  const [skip, setSkip] = useState(new URLSearchParams(location.search).get('skip') ?? 0);
  const [filters, setFilters] = useState([]);
  const [facets, setFacets] = useState({});
  const [isLoading, setIsLoading] = useState(true);

  let resultsPerPage = top;

  // Handle page changes in a controlled manner
  function handlePageChange(newPage) {
    setCurrentPage(newPage);
  }

  // Calculate skip value and fetch results when relevant parameters change
  useEffect(() => {
    // Calculate skip based on current page
    const calculatedSkip = (currentPage - 1) * top;
    
    // Only update if skip has actually changed
    if (calculatedSkip !== skip) {
      setSkip(calculatedSkip);
      return; // Skip the fetch since skip will change and trigger another useEffect
    }
    
    // Proceed with fetch
    setIsLoading(true);
    
    const body = {
      q: q,
      top: top,
      skip: skip,
      filters: filters
    };

    
    fetchInstance('/api/search', { body, method: 'POST' })
      .then(response => {
        setResults(response.results);
        setFacets(response.facets);
        setResultCount(response.count);
        setIsLoading(false);
      })
      .catch(error => {
        console.log(error);
        setIsLoading(false);
      });
  }, [q, top, skip, filters, currentPage]);

  // pushing the new search term to history when q is updated
  // allows the back button to work as expected when coming back from the details page
  useEffect(() => {
    navigate('/search?q=' + q);
    setCurrentPage(1);
    setFilters([]);
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [q]);


  let postSearchHandler = (searchTerm) => {
    setQ(searchTerm);
  }


  // filters should be applied across entire result set, 
  // not just within the current page
  const updateFilterHandler = (newFilters) => {

    // Reset paging
    setSkip(0);
    setCurrentPage(1);

    // Set filters
    setFilters(newFilters);
  };

  return (
    <main className="main main--search container-fluid">
      <div className="row">
        <div className="search-bar-column col-md-3">
          <div className="search-bar-column-container">
            <SearchBar postSearchHandler={postSearchHandler} query={q} width={false}></SearchBar>
          </div>
          <Facets facets={facets} filters={filters} setFilters={updateFilterHandler}></Facets>
        </div>
        <div className="search-bar-results">
          {isLoading ? (
            <div className="col-md-9">
              <CircularProgress />
            </div>
          ) : (
            <div className="search-results-container">
              <Results documents={results} top={top} skip={skip} count={resultCount} query={q}></Results>
              <Pager className="pager-style" currentPage={currentPage} resultCount={resultCount} resultsPerPage={resultsPerPage} onPageChange={handlePageChange}></Pager>
            </div>
          )}
        </div>
      </div>
    </main>
  );
}

To verify this integration, enter a search term in the website's search bar and confirm that the result list, result count, and facets all update.

Client: Suggestions from the catalog

The Suggest function API is called in the React app at \client\src\components\SearchBar\SearchBar.jsx as part of the Material UI Autocomplete component. This component uses the input text to search for authors and books that match. It then displays those possible matches as selectable items in the dropdown list.

import React, { useState, useEffect } from 'react';
import { TextField, Autocomplete, Button, Box } from '@mui/material';
import fetchInstance from '../../url-fetch';
import './SearchBar.css';

export default function SearchBar({ postSearchHandler, query, width }) {
  const [q, setQ] = useState(() => query || '');
  const [suggestions, setSuggestions] = useState([]);

  const search = (value) => {
    postSearchHandler(value);
  };

  useEffect(() => {
    if (q) {

      const body = { q, top: 5, suggester: 'sg' };

      fetchInstance('/api/suggest', { body, method: 'POST' })
      .then(response => {
        setSuggestions(response.suggestions.map(s => s.text));
      })
      .catch(error => {
        console.log(error);
        setSuggestions([]);
      });
    }
  }, [q]);


  const onInputChangeHandler = (event, value) => {
    setQ(value);
  };


  const onChangeHandler = (event, value) => {

    setQ(value);
    search(value);
  };

  const onEnterButton = (event) => {
    // if enter key is pressed
    if (event.key === 'Enter') {
      search(q);
    }
  };

  return (
    <div
      className={width ? "search-bar search-bar-wide" : "search-bar search-bar-narrow"}
    >
      <Box className="search-bar-box">
        <Autocomplete
          className="autocomplete"
          freeSolo
          value={q}
          options={suggestions}
          onInputChange={onInputChangeHandler}
          onChange={onChangeHandler}
          disableClearable
          renderInput={(params) => (
            <TextField
              {...params}
              id="search-box"
              className="form-control rounded-0"
              placeholder="What are you looking for?"
              onBlur={() => setSuggestions([])}
              onClick={() => setSuggestions([])}
              onKeyDown={onEnterButton}
            />
          )}
        />
        <div className="search-button" >
          <Button variant="contained" color="primary" onClick={() => {
            search(q)
          }
          }>
            Search
          </Button>
        </div>
      </Box>
    </div>
  );
}

To verify this integration, enter text in the website's search bar and confirm that matching book titles and authors appear in the autocomplete dropdown.

Function: Get specific document

The Document Lookup API retrieves the full document for a single book after a user selects it from the search results. The function reads a book id from the request's query string, uses SearchClientFactory to create an authenticated SearchClient, and calls GetDocumentAsync to look up that key in the good-books index. It returns the resulting document wrapped in a LookupOutput object.

using Azure;
using Azure.Core.Serialization;
using Azure.Identity;
using Azure.Search.Documents;
using Azure.Search.Documents.Models;
using Microsoft.Azure.Functions.Worker;
using Microsoft.Azure.Functions.Worker.Http;
using Microsoft.Extensions.Logging;
using System.Net;
using System.Text.Json;
using WebSearch.Models;

namespace WebSearch.Function
{
    public class Lookup
    {
        private readonly ILogger<Lookup> _logger;

        public Lookup(ILogger<Lookup> logger)
        {
            _logger = logger;
        }


        [Function("lookup")]
        public async Task<HttpResponseData> RunAsync(
            [HttpTrigger(AuthorizationLevel.Anonymous, "get", "post")] HttpRequestData req, 
            FunctionContext executionContext)
        {

            // Get Document Id
            var query = System.Web.HttpUtility.ParseQueryString(req.Url.Query);
            string documentId = query["id"].ToString();

            // Azure AI Search (managed identity by default; API key only when SEARCH_USE_KEY_AUTH=true)
            SearchClient searchClient = SearchClientFactory.CreateSearchClient();

            var getDocumentResponse = await searchClient.GetDocumentAsync<SearchDocument>(documentId);

            // Data to return 
            var output = new LookupOutput
            {
                Document = getDocumentResponse.Value
            };

            var response = req.CreateResponse(HttpStatusCode.Found);

            // Serialize data
            var serializer = new JsonObjectSerializer(
                new JsonSerializerOptions(JsonSerializerDefaults.Web));
            await response.WriteAsJsonAsync(output, serializer);

            return response;
        }
    }
}

To verify the Lookup function independently, call /api/lookup with a valid book id and confirm the response returns that book's full document.

Client: Get specific document

When a user selects a book from the search results, the Details page needs the complete document for that book, including fields not shown in the summary list. The Details page reads the book id from the route parameters and calls the Document Lookup API through /api/lookup when the component mounts. It stores the returned document in component state and renders it in the Result and Raw Data tabs. The following code in \client\src\pages\Details\Details.jsx performs this lookup during component initialization:

import React, { useState, useEffect } from "react";
import { useParams } from 'react-router-dom';
import Rating from '@mui/material/Rating';
import CircularProgress from '@mui/material/CircularProgress';
import Tabs from '@mui/material/Tabs';
import Tab from '@mui/material/Tab';
import Box from '@mui/material/Box';

import fetchInstance from '../../url-fetch';

import "./Details.css";


function CustomTabPanel(props) {
  const { children, value, index, ...other } = props;

  return (
    <div
      className="tab-panel"
      role="tabpanel"
      hidden={value !== index}
      id={`simple-tabpanel-${index}`}
      aria-labelledby={`simple-tab-${index}`}
      {...other}
       // Ensure it takes full width
    >
      {value === index && <Box className="tab-panel-value">{children}</Box>}
    </div>
  );
}

export default function BasicTabs() {
  const { id } = useParams();
  const [document, setDocument] = useState({});
  const [value, setValue] = React.useState(0);
  const [isLoading, setIsLoading] = useState(true);

  useEffect(() => {
    setIsLoading(true);
    fetchInstance('/api/lookup', { query: { id } })
      .then(response => {
        console.log(JSON.stringify(response))
        const doc = response.document;
        setDocument(doc);
        setIsLoading(false);
      })
      .catch(error => {
        console.log(error);
        setIsLoading(false);
      });

  }, [id]);

  const handleChange = (event, newValue) => {
    setValue(newValue);
  };


  if (isLoading || !id || Object.keys(document).length === 0) {
    return (
      <div className="loading-container">
        <CircularProgress />
        <p>Loading...</p>
      </div>
    );
  }

  return (
    <Box className="details-box-parent">
      <Box className="details-tab-box-header">
        <Tabs value={value} onChange={handleChange} aria-label="book-details-tabs">
          <Tab label="Result" />
          <Tab label="Raw Data" />
        </Tabs>
      </Box>
      <CustomTabPanel value={value} index={0} className="tab-panel box-content">
        <div className="card-body">
          <h5 className="card-title">{document.original_title}</h5>
          <img className="image" src={document.image_url} alt="Book cover"></img>
          <p className="card-text">{document.authors?.join('; ')} - {document.original_publication_year}</p>
          <p className="card-text">ISBN {document.isbn}</p>
          <Rating name="half-rating-read" value={parseInt(document.average_rating)} precision={0.1} readOnly></Rating>
          <p className="card-text">{document.ratings_count} Ratings</p>
        </div>
      </CustomTabPanel>
      <CustomTabPanel value={value} index={1} className="tab-panel">
        <div className="card-body text-left card-text details-custom-tab-panel-json-div" >
          <pre><code>
            {JSON.stringify(document, null, 2)}
          </code></pre>
        </div>
      </CustomTabPanel>
    </Box>
  );
}

To verify this integration, select a book from the search results and confirm that its details, including cover image, authors, and rating, appear on the Details page.

C# models that support the API

The Azure Functions API and the bulk import project share a set of C# model classes. These classes define the request bodies the client sends, such as search text, paging values, and filters. They also define the response shapes the client expects, such as search results, facet values, and a single looked-up document. Keeping these models in one file ensures the search, suggest, and document lookup endpoints stay consistent with the React client's expectations. The following models, defined in Models.cs, support the functions in this app:

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

namespace WebSearch.Models
{
    public class RequestBodyLookUp
    {
        [JsonPropertyName("id")]
        public string Id { get; set; }
    }

    public class RequestBodySuggest
    {
        [JsonPropertyName("q")]
        public string SearchText { get; set; }

        [JsonPropertyName("top")]
        public int Size { get; set; }

        [JsonPropertyName("suggester")]
        public string SuggesterName { get; set; }
    }

    public class RequestBodySearch
    {
        [JsonPropertyName("q")]
        public string SearchText { get; set; }

        [JsonPropertyName("skip")]
        public int Skip { get; set; }

        [JsonPropertyName("top")]
        public int Size { get; set; }

        [JsonPropertyName("filters")]
        public List<SearchFilter> Filters { get; set; }
    }

    public class SearchFilter
    {
        public string field { get; set; }
        public string value { get; set; }
    }

    public class FacetValue
    {
        public string value { get; set; }
        public long? count { get; set; }
    }

    class SearchOutput
    {
        [JsonPropertyName("count")]
        public long? Count { get; set; }
        [JsonPropertyName("results")]
        public List<SearchResult<SearchDocument>> Results { get; set; }
        [JsonPropertyName("facets")]
        public Dictionary<String, IList<FacetValue>> Facets { get; set; }
    }
    class LookupOutput
    {
        [JsonPropertyName("document")]
        public SearchDocument Document { get; set; }
    }
    public class BookModel
    {
        public string id { get; set; }
        public decimal? goodreads_book_id { get; set; }
        public decimal? best_book_id { get; set; }
        public decimal? work_id { get; set; }
        public decimal? books_count { get; set; }
        public string isbn { get; set; }
        public string isbn13 { get; set; }
        public string[] authors { get; set; }
        public decimal? original_publication_year { get; set; }
        public string original_title { get; set; }
        public string title { get; set; }
        public string language_code { get; set; }
        public double? average_rating { get; set; }
        public decimal? ratings_count { get; set; }
        public decimal? work_ratings_count { get; set; }
        public decimal? work_text_reviews_count { get; set; }
        public decimal? ratings_1 { get; set; }
        public decimal? ratings_2 { get; set; }
        public decimal? ratings_3 { get; set; }
        public decimal? ratings_4 { get; set; }
        public decimal? ratings_5 { get; set; }
        public string image_url { get; set; }
        public string small_image_url { get; set; }
    }
}

Next step

To continue learning about Azure AI Search development, try this next tutorial about indexing: