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Get API

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Get API

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Get Request

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A GetRequest requires the following arguments:

GetRequest getRequest = new GetRequest(
        "posts", 
        "doc",  
        "1");

	Index
	Type
	Document id

Optional arguments

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The following arguments can optionally be provided:

request.fetchSourceContext(FetchSourceContext.DO_NOT_FETCH_SOURCE);

Disable source retrieval, enabled by default

String[] includes = new String[]{"message", "*Date"};
String[] excludes = Strings.EMPTY_ARRAY;
FetchSourceContext fetchSourceContext =
        new FetchSourceContext(true, includes, excludes);
request.fetchSourceContext(fetchSourceContext);

Configure source inclusion for specific fields

String[] includes = Strings.EMPTY_ARRAY;
String[] excludes = new String[]{"message"};
FetchSourceContext fetchSourceContext =
        new FetchSourceContext(true, includes, excludes);
request.fetchSourceContext(fetchSourceContext);

Configure source exclusion for specific fields

request.storedFields("message"); 
GetResponse getResponse = client.get(request, RequestOptions.DEFAULT);
String message = getResponse.getField("message").getValue();

	Configure retrieval for specific stored fields (requires fields to be stored separately in the mappings)
	Retrieve the `message` stored field (requires the field to be stored separately in the mappings)

request.routing("routing");

Routing value

request.parent("parent");

Parent value

request.preference("preference");

Preference value

request.realtime(false);

Set realtime flag to false (true by default)

request.refresh(true);

Perform a refresh before retrieving the document (false by default)

request.version(2);

Version

request.versionType(VersionType.EXTERNAL);

Version type

Synchronous Execution

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When executing a GetRequest in the following manner, the client waits for the GetResponse to be returned before continuing with code execution:

GetResponse getResponse = client.get(getRequest, RequestOptions.DEFAULT);

Synchronous calls may throw an IOException in case of either failing to parse the REST response in the high-level REST client, the request times out or similar cases where there is no response coming back from the server.

In cases where the server returns a 4xx or 5xx error code, the high-level client tries to parse the response body error details instead and then throws a generic ElasticsearchException and adds the original ResponseException as a suppressed exception to it.

Asynchronous Execution

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Executing a GetRequest can also be done in an asynchronous fashion so that the client can return directly. Users need to specify how the response or potential failures will be handled by passing the request and a listener to the asynchronous get method:

client.getAsync(request, RequestOptions.DEFAULT, listener);

The GetRequest to execute and the ActionListener to use when the execution completes

The asynchronous method does not block and returns immediately. Once it is completed the ActionListener is called back using the onResponse method if the execution successfully completed or using the onFailure method if it failed. Failure scenarios and expected exceptions are the same as in the synchronous execution case.

A typical listener for get looks like:

ActionListener<GetResponse> listener = new ActionListener<GetResponse>() {
    @Override
    public void onResponse(GetResponse getResponse) {
        
    }

    @Override
    public void onFailure(Exception e) {
        
    }
};

	Called when the execution is successfully completed.
	Called when the whole `GetRequest` fails.

Get Response

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The returned GetResponse allows to retrieve the requested document along with its metadata and eventually stored fields.

String index = getResponse.getIndex();
String type = getResponse.getType();
String id = getResponse.getId();
if (getResponse.isExists()) {
    long version = getResponse.getVersion();
    String sourceAsString = getResponse.getSourceAsString();        
    Map<String, Object> sourceAsMap = getResponse.getSourceAsMap(); 
    byte[] sourceAsBytes = getResponse.getSourceAsBytes();          
} else {
    
}

	Retrieve the document as a `String`
	Retrieve the document as a `Map<String, Object>`
	Retrieve the document as a `byte[]`
	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 a get request is performed against an index that does not exist, the response has 404 status code, an ElasticsearchException gets thrown which needs to be handled as follows:

GetRequest request = new GetRequest("does_not_exist", "doc", "1");
try {
    GetResponse getResponse = client.get(request, RequestOptions.DEFAULT);
} catch (ElasticsearchException e) {
    if (e.status() == RestStatus.NOT_FOUND) {
        
    }
}

Handle the exception thrown because the index does not exist

In case a specific document version has been requested, and the existing document has a different version number, a version conflict is raised:

try {
    GetRequest request = new GetRequest("posts", "doc", "1").version(2);
    GetResponse getResponse = client.get(request, RequestOptions.DEFAULT);
} catch (ElasticsearchException exception) {
    if (exception.status() == RestStatus.CONFLICT) {
        
    }
}

The raised exception indicates that a version conflict error was returned

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