Docs: HighLevelRestClient#multiGet (#29095)

Add documentation for HighLevelRestClient#multiGet.

Relates to #28389.
This commit is contained in:
Nik Everett 2018-03-16 18:52:34 -04:00 committed by GitHub
parent 60cb476cc9
commit 2f21dc7129
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3 changed files with 377 additions and 1 deletions

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@ -37,10 +37,14 @@ import org.elasticsearch.action.delete.DeleteRequest;
import org.elasticsearch.action.delete.DeleteResponse;
import org.elasticsearch.action.get.GetRequest;
import org.elasticsearch.action.get.GetResponse;
import org.elasticsearch.action.get.MultiGetItemResponse;
import org.elasticsearch.action.get.MultiGetRequest;
import org.elasticsearch.action.get.MultiGetResponse;
import org.elasticsearch.action.index.IndexRequest;
import org.elasticsearch.action.index.IndexResponse;
import org.elasticsearch.action.support.ActiveShardCount;
import org.elasticsearch.action.support.WriteRequest;
import org.elasticsearch.action.support.WriteRequest.RefreshPolicy;
import org.elasticsearch.action.support.replication.ReplicationResponse;
import org.elasticsearch.action.update.UpdateRequest;
import org.elasticsearch.action.update.UpdateResponse;
@ -68,6 +72,11 @@ import java.util.Map;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;
import static org.hamcrest.Matchers.arrayWithSize;
import static org.hamcrest.Matchers.hasEntry;
import static org.hamcrest.Matchers.containsString;
import static org.hamcrest.Matchers.hasKey;
import static org.hamcrest.Matchers.not;
import static java.util.Collections.emptyMap;
import static java.util.Collections.singletonMap;
@ -809,7 +818,7 @@ public class CRUDDocumentationIT extends ESRestHighLevelClientTestCase {
{
GetRequest request = new GetRequest("posts", "doc", "1");
//tag::get-request-no-source
request.fetchSourceContext(new FetchSourceContext(false)); // <1>
request.fetchSourceContext(FetchSourceContext.DO_NOT_FETCH_SOURCE); // <1>
//end::get-request-no-source
GetResponse getResponse = client.get(request);
assertNull(getResponse.getSourceInternal());
@ -1066,4 +1075,201 @@ public class CRUDDocumentationIT extends ESRestHighLevelClientTestCase {
// end::bulk-processor-options
}
}
public void testMultiGet() throws Exception {
RestHighLevelClient client = highLevelClient();
{
String mappings = "{\n" +
" \"mappings\" : {\n" +
" \"type\" : {\n" +
" \"properties\" : {\n" +
" \"foo\" : {\n" +
" \"type\": \"text\",\n" +
" \"store\": true\n" +
" }\n" +
" }\n" +
" }\n" +
" }\n" +
"}";
NStringEntity entity = new NStringEntity(mappings, ContentType.APPLICATION_JSON);
Response response = client().performRequest("PUT", "/index", Collections.emptyMap(), entity);
assertEquals(200, response.getStatusLine().getStatusCode());
}
Map<String, Object> source = new HashMap<>();
source.put("foo", "val1");
source.put("bar", "val2");
source.put("baz", "val3");
client.index(new IndexRequest("index", "type", "example_id")
.source(source)
.setRefreshPolicy(RefreshPolicy.IMMEDIATE));
{
// tag::multi-get-request
MultiGetRequest request = new MultiGetRequest();
request.add(new MultiGetRequest.Item(
"index", // <1>
"type", // <2>
"example_id")); // <3>
request.add(new MultiGetRequest.Item("index", "type", "another_id")); // <4>
// end::multi-get-request
// Add a missing index so we can test it.
request.add(new MultiGetRequest.Item("missing_index", "type", "id"));
// tag::multi-get-request-item-extras
request.add(new MultiGetRequest.Item("index", "type", "with_routing")
.routing("some_routing")); // <1>
request.add(new MultiGetRequest.Item("index", "type", "with_parent")
.parent("some_parent")); // <2>
request.add(new MultiGetRequest.Item("index", "type", "with_version")
.versionType(VersionType.EXTERNAL) // <3>
.version(10123L)); // <4>
// end::multi-get-request-item-extras
// tag::multi-get-request-top-level-extras
request.preference("some_preference"); // <1>
request.realtime(false); // <2>
request.refresh(true); // <3>
// end::multi-get-request-top-level-extras
// tag::multi-get-execute
MultiGetResponse response = client.multiGet(request);
// end::multi-get-execute
// tag::multi-get-response
MultiGetItemResponse firstItem = response.getResponses()[0];
assertNull(firstItem.getFailure()); // <1>
GetResponse firstGet = firstItem.getResponse(); // <2>
String index = firstItem.getIndex();
String type = firstItem.getType();
String id = firstItem.getId();
if (firstGet.isExists()) {
long version = firstGet.getVersion();
String sourceAsString = firstGet.getSourceAsString(); // <3>
Map<String, Object> sourceAsMap = firstGet.getSourceAsMap(); // <4>
byte[] sourceAsBytes = firstGet.getSourceAsBytes(); // <5>
} else {
// <6>
}
// end::multi-get-response
assertTrue(firstGet.isExists());
assertEquals(source, firstGet.getSource());
MultiGetItemResponse missingIndexItem = response.getResponses()[2];
// tag::multi-get-indexnotfound
assertNull(missingIndexItem.getResponse()); // <1>
Exception e = missingIndexItem.getFailure().getFailure(); // <2>
ElasticsearchException ee = (ElasticsearchException) e; // <3>
// TODO status is broken! fix in a followup
// assertEquals(RestStatus.NOT_FOUND, ee.status()); // <4>
assertThat(e.getMessage(),
containsString("reason=no such index")); // <5>
// end::multi-get-indexnotfound
// tag::multi-get-execute-listener
ActionListener<MultiGetResponse> listener = new ActionListener<MultiGetResponse>() {
@Override
public void onResponse(MultiGetResponse response) {
// <1>
}
@Override
public void onFailure(Exception e) {
// <2>
}
};
// end::multi-get-execute-listener
// Replace the empty listener by a blocking listener in test
final CountDownLatch latch = new CountDownLatch(1);
listener = new LatchedActionListener<>(listener, latch);
// tag::multi-get-execute-async
client.multiGetAsync(request, listener); // <1>
// end::multi-get-execute-async
assertTrue(latch.await(30L, TimeUnit.SECONDS));
}
{
MultiGetRequest request = new MultiGetRequest();
// tag::multi-get-request-no-source
request.add(new MultiGetRequest.Item("index", "type", "example_id")
.fetchSourceContext(FetchSourceContext.DO_NOT_FETCH_SOURCE)); // <1>
// end::multi-get-request-no-source
MultiGetItemResponse item = unwrapAndAssertExample(client.multiGet(request));
assertNull(item.getResponse().getSource());
}
{
MultiGetRequest request = new MultiGetRequest();
// tag::multi-get-request-source-include
String[] includes = new String[] {"foo", "*r"};
String[] excludes = Strings.EMPTY_ARRAY;
FetchSourceContext fetchSourceContext =
new FetchSourceContext(true, includes, excludes);
request.add(new MultiGetRequest.Item("index", "type", "example_id")
.fetchSourceContext(fetchSourceContext)); // <1>
// end::multi-get-request-source-include
MultiGetItemResponse item = unwrapAndAssertExample(client.multiGet(request));
assertThat(item.getResponse().getSource(), hasEntry("foo", "val1"));
assertThat(item.getResponse().getSource(), hasEntry("bar", "val2"));
assertThat(item.getResponse().getSource(), not(hasKey("baz")));
}
{
MultiGetRequest request = new MultiGetRequest();
// tag::multi-get-request-source-exclude
String[] includes = Strings.EMPTY_ARRAY;
String[] excludes = new String[] {"foo", "*r"};
FetchSourceContext fetchSourceContext =
new FetchSourceContext(true, includes, excludes);
request.add(new MultiGetRequest.Item("index", "type", "example_id")
.fetchSourceContext(fetchSourceContext)); // <1>
// end::multi-get-request-source-exclude
MultiGetItemResponse item = unwrapAndAssertExample(client.multiGet(request));
assertThat(item.getResponse().getSource(), not(hasKey("foo")));
assertThat(item.getResponse().getSource(), not(hasKey("bar")));
assertThat(item.getResponse().getSource(), hasEntry("baz", "val3"));
}
{
MultiGetRequest request = new MultiGetRequest();
// tag::multi-get-request-stored
request.add(new MultiGetRequest.Item("index", "type", "example_id")
.storedFields("foo")); // <1>
MultiGetResponse response = client.multiGet(request);
MultiGetItemResponse item = response.getResponses()[0];
String value = item.getResponse().getField("foo").getValue(); // <2>
// end::multi-get-request-stored
assertNull(item.getResponse().getSource());
assertEquals("val1", value);
}
{
// tag::multi-get-conflict
MultiGetRequest request = new MultiGetRequest();
request.add(new MultiGetRequest.Item("index", "type", "example_id")
.version(1000L));
MultiGetResponse response = client.multiGet(request);
MultiGetItemResponse item = response.getResponses()[0];
assertNull(item.getResponse()); // <1>
Exception e = item.getFailure().getFailure(); // <2>
ElasticsearchException ee = (ElasticsearchException) e; // <3>
// TODO status is broken! fix in a followup
// assertEquals(RestStatus.CONFLICT, ee.status()); // <4>
assertThat(e.getMessage(),
containsString("version conflict, current version [1] is "
+ "different than the one provided [1000]")); // <5>
// end::multi-get-conflict
}
}
private MultiGetItemResponse unwrapAndAssertExample(MultiGetResponse response) {
assertThat(response.getResponses(), arrayWithSize(1));
MultiGetItemResponse item = response.getResponses()[0];
assertEquals("index", item.getIndex());
assertEquals("type", item.getType());
assertEquals("example_id", item.getId());
return item;
}
}

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@ -0,0 +1,168 @@
[[java-rest-high-document-multi-get]]
=== Multi-Get API
The `multiGet` API executes multiple <<java-rest-high-document-get,`get`>>
requests in a single http request in parallel.
[[java-rest-high-document-mulit-get-request]]
==== Multi-Get Request
A `MultiGetRequest` is built empty and you add `MultiGetRequest.Item`s to
configure what to fetch:
["source","java",subs="attributes,callouts,macros"]
--------------------------------------------------
include-tagged::{doc-tests}/CRUDDocumentationIT.java[multi-get-request]
--------------------------------------------------
<1> Index
<2> Type
<3> Document id
<4> Add another item to fetch
==== Optional arguments
`multiGet` supports the same optional arguments that the
<<java-rest-high-document-get-request-optional-arguments,`get` API>> supports.
You can set most of these on the `Item`:
["source","java",subs="attributes,callouts,macros"]
--------------------------------------------------
include-tagged::{doc-tests}/CRUDDocumentationIT.java[multi-get-request-no-source]
--------------------------------------------------
<1> Disable source retrieval, enabled by default
["source","java",subs="attributes,callouts,macros"]
--------------------------------------------------
include-tagged::{doc-tests}/CRUDDocumentationIT.java[multi-get-request-source-include]
--------------------------------------------------
<1> Configure source inclusion for specific fields
["source","java",subs="attributes,callouts,macros"]
--------------------------------------------------
include-tagged::{doc-tests}/CRUDDocumentationIT.java[multi-get-request-source-exclude]
--------------------------------------------------
<1> Configure source exclusion for specific fields
["source","java",subs="attributes,callouts,macros"]
--------------------------------------------------
include-tagged::{doc-tests}/CRUDDocumentationIT.java[multi-get-request-stored]
--------------------------------------------------
<1> Configure retrieval for specific stored fields (requires fields to be
stored separately in the mappings)
<2> Retrieve the `foo` stored field (requires the field to be stored
separately in the mappings)
["source","java",subs="attributes,callouts,macros"]
--------------------------------------------------
include-tagged::{doc-tests}/CRUDDocumentationIT.java[multi-get-request-item-extras]
--------------------------------------------------
<1> Routing value
<2> Parent value
<3> Version
<4> Version type
{ref}/search-request-preference.html[`preference`],
{ref}/docs-get.html#realtime[`realtime`]
and
{ref}/docs-get.html#get-refresh[`refresh`] can be set on the main request but
not on any items:
["source","java",subs="attributes,callouts,macros"]
--------------------------------------------------
include-tagged::{doc-tests}/CRUDDocumentationIT.java[multi-get-request-top-level-extras]
--------------------------------------------------
<1> Preference value
<2> Set realtime flag to `false` (`true` by default)
<3> Perform a refresh before retrieving the document (`false` by default)
[[java-rest-high-document-multi-get-sync]]
==== Synchronous Execution
After building the `MultiGetRequest` you can execute it synchronously with
`multiGet`:
["source","java",subs="attributes,callouts,macros"]
--------------------------------------------------
include-tagged::{doc-tests}/CRUDDocumentationIT.java[multi-get-execute]
--------------------------------------------------
[[java-rest-high-document-multi-get-async]]
==== Asynchronous Execution
The asynchronous execution of a multi get request requires both the
`MultiGetRequest` instance and an `ActionListener` instance to be passed to
the asynchronous method:
["source","java",subs="attributes,callouts,macros"]
--------------------------------------------------
include-tagged::{doc-tests}/CRUDDocumentationIT.java[multi-get-execute-async]
--------------------------------------------------
<1> The `MultiGetRequest` to execute and the `ActionListener` to use when
the execution completes.
The asynchronous method does not block and returns immediately. Once the
request completed the `ActionListener` is called back using the `onResponse`
method if the execution successfully completed or using the `onFailure` method
if it failed.
A typical listener for `MultiGetResponse` looks like:
["source","java",subs="attributes,callouts,macros"]
--------------------------------------------------
include-tagged::{doc-tests}/CRUDDocumentationIT.java[multi-get-execute-listener]
--------------------------------------------------
<1> Called when the execution is successfully completed. The response is
provided as an argument.
<2> Called in case of failure. The raised exception is provided as an argument.
[[java-rest-high-document-multi-get-response]]
==== Multi Get Response
The returned `MultiGetResponse` contains a list of `MultiGetItemResponse`s in
`getResponses` in the same order that they were requested.
`MultiGetItemResponse` contains *either* a
<<java-rest-high-document-get-response, `GetResponse`>> if the get succeeded
or a `MultiGetResponse.Failure` if it failed. A success looks just like a
normal `GetResponse`.
["source","java",subs="attributes,callouts,macros"]
--------------------------------------------------
include-tagged::{doc-tests}/CRUDDocumentationIT.java[multi-get-response]
--------------------------------------------------
<1> `getFailure` returns null because there isn't a failure.
<2> `getResponse` returns the `GetResponse`.
<3> Retrieve the document as a `String`
<4> Retrieve the document as a `Map<String, Object>`
<5> Retrieve the document as a `byte[]`
<6> Handle the scenario where the document was not found. Note that although
the returned response has `404` status code, a valid `GetResponse` is
returned rather than an exception thrown. Such response does not hold any
source document and its `isExists` method returns `false`.
When one of the subrequests as performed against an index that does not exist
`getFailure` will contain an exception:
["source","java",subs="attributes,callouts,macros"]
--------------------------------------------------
include-tagged::{doc-tests}/CRUDDocumentationIT.java[multi-get-indexnotfound]
--------------------------------------------------
<1> `getResponse` is null.
<2> `getFailure` isn't and contains an `Exception`.
<3> That `Exception` is actually an `ElasticsearchException`
<4> and it has a status of `NOT_FOUND`. It'd have been an HTTP 404 if this
wasn't a multi get.
<5> `getMessage` explains the actual cause, `no such index`.
In case a specific document version has been requested, and the existing
document has a different version number, a version conflict is raised:
["source","java",subs="attributes,callouts,macros"]
--------------------------------------------------
include-tagged::{doc-tests}/CRUDDocumentationIT.java[multi-get-conflict]
--------------------------------------------------
<1> `getResponse` is null.
<2> `getFailure` isn't and contains an `Exception`.
<3> That `Exception` is actuall and `ElasticsearchException`
<4> and it has a status of `CONFLICT`. It'd have been an HTTP 409 if this
wasn't a multi get.
<5> `getMessage` explains the actual cause, `

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@ -14,6 +14,7 @@ Single document APIs::
[[multi-doc]]
Multi-document APIs::
* <<java-rest-high-document-bulk>>
* <<java-rest-high-document-multi-get>>
include::document/index.asciidoc[]
include::document/get.asciidoc[]
@ -21,6 +22,7 @@ include::document/exists.asciidoc[]
include::document/delete.asciidoc[]
include::document/update.asciidoc[]
include::document/bulk.asciidoc[]
include::document/multi-get.asciidoc[]
== Search APIs