<p dir="auto"><strong>Elasticsearch version</strong>: 5.0.0-beta1</p>
<p dir="auto"><strong>Plugins installed</strong>: []</p>
<p dir="auto"><strong>JVM version</strong>: 1.8.0_72</p>
<p dir="auto"><strong>OS version</strong>: Ubuntu 15</p>
<p dir="auto"><strong>Description of the problem including expected versus actual behavior</strong>:<br>
As described here <a href="https://www.elastic.co/guide/en/elasticsearch/reference/5.0/search-suggesters-completion.html#querying" rel="nofollow">https://www.elastic.co/guide/en/elasticsearch/reference/5.0/search-suggesters-completion.html#querying</a>  one can use source filtering while returning suggestions under _suggest endpoint. However, using the source filtering returns following error to me.<br>
<a target="_blank" rel="noopener noreferrer nofollow" href="https://cloud.githubusercontent.com/assets/10341430/19214302/2c4a8924-8d9d-11e6-88af-ba838a879c97.png"><img src="https://cloud.githubusercontent.com/assets/10341430/19214302/2c4a8924-8d9d-11e6-88af-ba838a879c97.png" alt="image" style="max-width: 100%;"></a></p>
<p dir="auto"><strong>Steps to reproduce</strong>:</p>
<ol dir="auto">
<li>Follow examples mentioned on the above mentioned url for creating index with mapping and indexing document.</li>
<li>Use following query for the suggestion<br>
curl -XPOST "<a href="http://localhost:9200/music/_suggest" rel="nofollow">http://localhost:9200/music/_suggest</a>" -d'<br>
{<br>
"_source": "completion.*",<br>
"song-suggest" : {<br>
"prefix" : "nir",<br>
"completion" : {<br>
"field" : "suggest"<br>
}<br>
}<br>
}'</li>
</ol>
<p dir="auto"><strong>Looking at the documentation, i also wonder why to use completion.* as my source filtered field. Shouldn't it be the name of the field which exist in the document??</strong></p>
<p dir="auto"><em>Surprisingly there is no exception thrown in Elasticsearch log file.</em></p>
<p dir="auto">I found this while going through snippets that aren't marked <code class="notranslate">// CONSOLE</code>. In this case the <a href="https://github.com/elastic/elasticsearch/blame/master/docs/reference/search/suggesters/completion-suggest.asciidoc#L201-L222">this</a> snippet looks to suggest something that isn't implemented.</p>