public String invokeUpdateHandler(String updateHandlerUri, String docId,
                                      Params params) {
        assertNotEmpty(params, "params");
        return db.invokeUpdateHandler(updateHandlerUri, docId, params.getInternalParams());
    }
public String invokeUpdateHandler ( String updateHandlerUri , String docId , Params params ) { assertNotEmpty ( params , "params" ) ; return db . invokeUpdateHandler ( updateHandlerUri , docId , params . getInternalParams ( ) ) ; }
Invokes an Update Handler.
<P>Example usage:</P>
<pre>
{@code
final String newValue = "foo bar";
Params params = new Params()
.addParam("field", "title")
.addParam("value", newValue);
String output = db.invokeUpdateHandler("example/example_update", "exampleId", params);

}
</pre>
<pre>
Params params = new Params()
.addParam("field", "foo")
.addParam("value", "bar");
String output = dbClient.invokeUpdateHandler("designDoc/update1", "docId", params);
</pre>

@param updateHandlerUri The Update Handler URI, in the format: <code>designDoc/update1</code>
@param docId            The document id to update.
If no id is provided, then a document will be created.
@param params           The query parameters as {@link Params}.
@return The output of the request.
@see <a
href="https://console.bluemix.net/docs/services/Cloudant/api/design_documents.html#update-handlers"
target="_blank">Design documents - update handlers</a>