Support PUT /indexes/{name} for create-or-update (closes #30) (#31)

* Support PUT /indexes/{name} for create-or-update semantics

Adds a PUT handler that creates the index when absent and overwrites
its schema when present, matching Azure AI Search's CreateOrUpdateIndex
behavior so the Azure SDK's CreateOrUpdateIndexAsync works against the
emulator. On update, cached Lucene reader/directory entries are cleared
so schema changes take effect. Closes #30.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* Fix HACK comment tag in new PUT handler

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: IndifferentDisdain

AzureSearchEmulator.IntegrationTests/EmulatorIntegrationTests.cs

@@ -319,6 +319,78 @@ public async Task SearchDocuments_WithPaging_ShouldReturnPagedResults()
         await indexClient.DeleteIndexAsync(indexName);
     }
 
+    [Fact]
+    public async Task CreateOrUpdateIndex_WhenIndexDoesNotExist_ShouldCreate()
+    {
+        // Arrange
+        const string indexName = "test-createorupdate-create";
+        var indexClient = factory.CreateSearchIndexClient();
+
+        // Ensure a clean slate
+        try
+        {
+            await indexClient.DeleteIndexAsync(indexName);
+        }
+        catch (Azure.RequestFailedException ex) when (ex.Status == 404)
+        {
+            // expected
+        }
+
+        var index = new SearchIndex(indexName)
+        {
+            Fields =
+            [
+                new SearchField(nameof(Product.Id), SearchFieldDataType.String) { IsKey = true, IsStored = true, IsSearchable = true, IsFilterable = true },
+                new SearchField(nameof(Product.Name), SearchFieldDataType.String) { IsSearchable = true, IsStored = true }
+            ]
+        };
+
+        // Act - PUT to a non-existent index should create it
+        var result = await indexClient.CreateOrUpdateIndexAsync(index);
+
+        // Assert
+        Assert.NotNull(result);
+        Assert.Equal(indexName, result.Value.Name);
+
+        var retrieved = await indexClient.GetIndexAsync(indexName);
+        Assert.NotNull(retrieved);
+        Assert.Equal(indexName, retrieved.Value.Name);
+        Assert.Equal(2, retrieved.Value.Fields.Count);
+
+        // Cleanup
+        await indexClient.DeleteIndexAsync(indexName);
+    }
+
+    [Fact]
+    public async Task CreateOrUpdateIndex_WhenIndexExists_ShouldUpdateSchema()
+    {
+        // Arrange
+        const string indexName = "test-createorupdate-update";
+        var indexClient = factory.CreateSearchIndexClient();
+
+        await CreateIndexAsync(indexClient, indexName);
+
+        // Pull the current index and add a backward-compatible field
+        var existing = (await indexClient.GetIndexAsync(indexName)).Value;
+        var originalFieldCount = existing.Fields.Count;
+
+        existing.Fields.Add(new SearchField("Tags", SearchFieldDataType.String) { IsFilterable = true, IsStored = true });
+
+        // Act - PUT on an existing index should update its schema
+        var result = await indexClient.CreateOrUpdateIndexAsync(existing);
+
+        // Assert
+        Assert.NotNull(result);
+        Assert.Equal(indexName, result.Value.Name);
+
+        var retrieved = await indexClient.GetIndexAsync(indexName);
+        Assert.Equal(originalFieldCount + 1, retrieved.Value.Fields.Count);
+        Assert.Contains(retrieved.Value.Fields, f => f.Name == "Tags");
+
+        // Cleanup
+        await indexClient.DeleteIndexAsync(indexName);
+    }
+
     [Fact]
     public async Task DeleteIndex_ShouldSucceed()
     {

AzureSearchEmulator/Controllers/IndexesController.cs

@@ -64,6 +64,47 @@ public async Task<IActionResult> Post() //([FromBody] SearchIndex? index)
         return Created(index);
     }
 
+    [HttpPut]
+    [Route("indexes({key})")]
+    [Route("indexes/{key}")]
+    public async Task<IActionResult> Put(string key)
+    {
+        // Strip quotes that may be captured from OData-style URLs
+        key = key.Trim('\'');
+
+        // HACK.JS: For some reason, having this as a parameter with [FromBody] fails to deserialize properly.
+        using var sr = new StreamReader(Request.Body);
+        var indexJson = await sr.ReadToEndAsync();
+        var index = JsonSerializer.Deserialize<SearchIndex>(indexJson, jsonSerializerOptions);
+
+        if (index == null || !ModelState.IsValid)
+        {
+            return BadRequest(ModelState);
+        }
+
+        if (!string.Equals(index.Name, key, StringComparison.OrdinalIgnoreCase))
+        {
+            ModelState.AddModelError(nameof(index.Name), "The index name in the request body must match the name in the URL.");
+            return BadRequest(ModelState);
+        }
+
+        var existing = await searchIndexRepository.Get(key);
+
+        if (existing == null)
+        {
+            await searchIndexRepository.Create(index);
+            return Created(index);
+        }
+
+        await searchIndexRepository.Update(index);
+
+        // Clear cached Lucene resources so schema changes take effect
+        luceneIndexReaderFactory.ClearCachedReader(index.Name);
+        luceneDirectoryFactory.ClearCachedDirectory(index.Name);
+
+        return Ok(index);
+    }
+
     [HttpDelete]
     [Route("indexes({key})")]
     [Route("indexes/{key}")]

AzureSearchEmulator/Repositories/FileSearchIndexRepository.cs

@@ -62,6 +62,20 @@ public Task Create(SearchIndex index)
         return WriteAllTextAsync(file, json);
     }
 
+    public Task Update(SearchIndex index)
+    {
+        if (!Directory.Exists(_options.IndexesDirectory))
+        {
+            Directory.CreateDirectory(_options.IndexesDirectory);
+        }
+
+        string file = GetIndexFileName(index.Name);
+
+        string json = JsonSerializer.Serialize(index, jsonSerializerOptions);
+
+        return WriteAllTextAsync(file, json);
+    }
+
     public Task<bool> Delete(SearchIndex index)
     {
         if (!Directory.Exists(_options.IndexesDirectory))

AzureSearchEmulator/Repositories/ISearchIndexRepository.cs

@@ -10,5 +10,7 @@ public interface ISearchIndexRepository
 
     Task Create(SearchIndex index);
 
+    Task Update(SearchIndex index);
+
     Task<bool> Delete(SearchIndex index);
 }