[Backport 1.x] Add higher-level HTTP DSL methods (#447)

CHANGELOG.md

@@ -6,6 +6,7 @@ Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 - Added support for point-in-time search and associated APIs ([#405](https://github.com/opensearch-project/opensearch-net/pull/405))
 - Added support for the component template APIs ([#411](https://github.com/opensearch-project/opensearch-net/pull/411))
 - Added support for the composable index template APIs ([#437](https://github.com/opensearch-project/opensearch-net/pull/437))
+- Added high-level DSL for raw HTTP methods ([#447](https://github.com/opensearch-project/opensearch-net/pull/447))
 
 ### Deprecated
 - Deprecated the low-level `IndexTemplateV2` APIs in favour of the new `ComposableIndexTemplate` APIs ([#454](https://github.com/opensearch-project/opensearch-net/pull/454))

USER_GUIDE.md

@@ -260,3 +260,12 @@ var client = new OpenSearchLowLevelClient(config);
 ```
 
 Note the main difference here is that we are instantiating an `OpenSearchLowLevelClient` rather than `OpenSearchClient`, and `ConnectionConfiguration` instead of `ConnectionSettings`.
+
+
+## Advanced Features
+
+- [Bulk Requests](guides/bulk.md)
+- [Document Lifecycle](guides/document-lifecycle.md)
+- [Index Template](guides/index-template.md)
+- [Making Raw JSON REST Requests](guides/json.md)
+- [Search](guides/search.md)

guides/bulk.md

@@ -0,0 +1,155 @@
+# Bulk
+
+In this guide, you'll learn how to use the OpenSearch .NET Client API to perform bulk operations. You'll learn how to index, update, and delete multiple documents in a single request.
+
+## Setup
+
+First, create a client instance with the following code:
+
+```cs
+var nodeAddress = new Uri("http://myserver:9200");
+var client = new OpenSearchClient(nodeAddress);
+```
+
+Next, create an index named `movies` and another named `books` with the default settings:
+
+```cs
+var movies = "movies";
+var books = "books";
+if (!(await client.Indices.ExistsAsync(movies)).Exists) {
+  await client.Indices.CreateAsync(movies);
+}
+
+if (!(await client.Indices.ExistsAsync(books)).Exists) {
+  await client.Indices.CreateAsync(books);
+}
+```
+
+## Bulk API
+
+The `bulk` API action allows you to perform document operations in a single request. The body of the request is an array of objects that contains the bulk operations and the target documents to index, create, update, or delete.
+
+### Indexing multiple documents
+
+The following code creates two documents in the `movies` index and one document in the `books` index:
+
+```cs
+var response = await client.BulkAsync(b => b
+    .Index<object>(i => i
+        .Index(movies)
+        .Id(1)
+        .Document(new { Title = "Beauty and the Beast", Year = 1991 })
+    )
+    .Index<object>(i => i
+        .Index(movies)
+        .Id(2)
+        .Document(new { Title = "Beauty and the Beast - Live Action", Year = 2017 })
+    )
+    .Index<object>(i => i
+        .Index(books)
+        .Id(1)
+        .Document(new { Title = "The Lion King", Year = 1994 })
+    ));
+```
+
+### Creating multiple documents
+
+Similarly, instead of calling the `create` method for each document, you can use the `bulk` API to create multiple documents in a single request. The following code creates three documents in the `movies` index and one in the `books` index:
+
+```cs
+var response = await client.BulkAsync(b => b
+    .Index(movies)
+    .CreateMany(new[]
+    {
+        new { Title = "Beauty and the Beast 2", Year = 2030 },
+        new { Title = "Beauty and the Beast 3", Year = 2031 },
+        new { Title = "Beauty and the Beast 4", Year = 2049 }
+    })
+    .Create<object>(i => i
+        .Index(books)
+        .Document(new { Title = "The Lion King 2", Year = 1998 })
+    ));
+```
+
+Note that we specified only the `_index` for the last document in the request body. This is because the `bulk` method accepts an `index` parameter that specifies the default `_index` for all bulk operations in the request body. Moreover, we omit the `_id` for each document and let OpenSearch generate them for us in this example, just like we can with the `create` method.
+
+### Updating multiple documents
+
+```cs
+var response = await client.BulkAsync(b => b
+    .Index(movies)
+    .Update<object>(i => i
+        .Id(1)
+        .Doc(new { Year = 1992 })
+    )
+    .Update<object>(i => i
+        .Id(2)
+        .Doc(new { Year = 2018 })
+    ));
+```
+
+### Deleting multiple documents
+
+```cs
+var response = await client.BulkAsync(b => b
+    .Index(movies)
+    .DeleteMany<object>(new long[] { 1, 2 }));
+```
+
+### Mix and match operations
+
+You can mix and match the different operations in a single request. The following code creates two documents, updates one document, and deletes another document:
+
+```cs
+var response = await client.BulkAsync(b => b
+    .Index(movies)
+    .CreateMany(new[]
+    {
+        new { Title = "Beauty and the Beast 5", Year = 2050 },
+        new { Title = "Beauty and the Beast 6", Year = 2051 }
+    })
+    .Update<object>(i => i
+        .Id(3)
+        .Doc(new { Year = 2052 })
+    )
+    .Delete<object>(i => i.Id(4)));
+```
+
+### Handling errors
+
+The `bulk` API returns an array of responses for each operation in the request body. Each response contains a `status` field that indicates whether the operation was successful or not. If the operation was successful, the `status` field is set to a `2xx` code. Otherwise, the response contains an error message in the `error` field.
+
+The following code shows how to look for errors in the response:
+
+```cs
+var response = await client.BulkAsync(b => b
+    .Index(movies)
+    .Create<object>(i => i
+        .Id(1)
+        .Document(new { Title = "Beauty and the Beast", Year = 1991 })
+    )
+    .Create<object>(i => i
+        .Id(2)
+        .Document(new { Title = "Beauty and the Beast 2", Year = 2030 })
+    )
+    .Create<object>(i => i // document already exists error
+        .Id(1)
+        .Document(new { Title = "Beauty and the Beast 3", Year = 2031 })
+    )
+    .Create<object>(i => i // document already exists error
+        .Id(2)
+        .Document(new { Title = "Beauty and the Beast 4", Year = 2049 })
+    ));
+
+foreach (var item in response.ItemsWithErrors) {
+    Console.WriteLine(item.Error.Reason);
+}
+```
+
+## Cleanup
+
+To clean up the resources created in this guide, delete the `movies` and `books` indices:
+
+```cs
+await client.Indices.DeleteAsync(new[] { movies, books });
+```