feat(clients): add helper to check if an index exists (#3646)

Co-authored-by: Thomas Raffray <Fluf22@users.noreply.github.com>

Author: millotp

clients/algoliasearch-client-csharp/algoliasearch/Utils/SearchClientExtensions.cs

@@ -593,4 +593,24 @@ private static async Task<List<TU>> CreateIterable<TU>(Func<TU, Task<TU>> execut
 
     return responses;
   }
+
+  public bool Exists(string indexName, CancellationToken cancellationToken = default) => AsyncHelper.RunSync(() => IndexExistsAsync(indexName, cancellationToken));
+
+  public async Task<bool> IndexExistsAsync(string indexName, CancellationToken cancellationToken = default)
+  {
+    try
+    {
+      await GetSettingsAsync(indexName, null, cancellationToken);
+    }
+    catch (AlgoliaApiException ex) when (ex.HttpErrorCode == 404)
+    {
+      return await Task.FromResult(false);
+    }
+    catch (Exception ex)
+    {
+      throw ex;
+    }
+
+    return await Task.FromResult(true);
+  }
 }

clients/algoliasearch-client-kotlin/client/src/commonMain/kotlin/com/algolia/client/extensions/SearchClient.kt

@@ -521,3 +521,16 @@ public fun securedApiKeyRemainingValidity(apiKey: String): Duration {
   val validUntil = Instant.fromEpochMilliseconds(match.groupValues[1].toLong())
   return validUntil - Clock.System.now()
 }
+
+public suspend fun SearchClient.indexExists(indexName: String): Boolean {
+  try {
+    getSettings(indexName)
+  } catch (e: AlgoliaApiException) {
+    if (e.httpErrorCode == 404) {
+      return false
+    }
+    throw e
+  }
+
+  return true
+}