title: With Elasticsearch .NET and NEST 6.x : How to MultiGet documents from multiples indices
body: <pre><code>var ids = new Dictionary&lt;string, List&lt;string&gt;&gt;();
  ids["Topic"] = new List&lt;string&gt; {"KL7KJ2QBWD77yvpxyjvd", "374wJ2QBWD77yvpxDjpX", "B7499GMBWD77yvpxFzgW"};
  ids["Prod"] = new List&lt;string&gt;();
  ids["Account"] = new List&lt;string&gt;();
  </code></pre>
  
  <p>I made this fluent NEST query:</p>
  
  <pre><code>var results = client.MultiGet(m =&gt; 
  m.Index("topics").GetMany&lt;Topic&gt;(ids["Topic"])
  
  .Index("prods").GetMany&lt;Prod&gt;(ids["Prod"])
  
  .Index("accounts").GetMany&lt;Account&gt;(ids["Account"])
  </code></pre>
  
  <p>it's generating the request below. We see the request use only the last index set which is "accounts" (and this is not what I need) :</p>
  
  <pre><code>http://localhost:9200/accounts/_mget?pretty=true
  {
    "docs": [
      {
        "_type": "Topic",
        "_id": "KL7KJ2QBWD77yvpxyjvd"
      },
      {
        "_type": "Topic",
        "_id": "374wJ2QBWD77yvpxDjpX"
      },
      {
        "_type": "Topic",
        "_id": "B7499GMBWD77yvpxFzgW"
      }
    ]
  }
  # Response:
  {
    "docs" : [
      {
        "_index" : "accounts",
        "_type" : "Topic",
        "_id" : "KL7KJ2QBWD77yvpxyjvd",
        "found" : false
      },
      {
        "_index" : "accounts",
        "_type" : "Topic",
        "_id" : "374wJ2QBWD77yvpxDjpX",
        "found" : false
      },
      {
        "_index" : "accounts",
            "_type" : "Topic",
        "_id" : "B7499GMBWD77yvpxFzgW",
        "found" : false
      }
    ]
  }
  </code></pre>
  
  <p>In fact I would like to create in fluent NEST the following (valid) Elasticsearch query request (with no specific index) : </p>
  
  <pre><code>http://localhost:9200/_mget?pretty=true
  {
    "docs": [
      {
        "_index": "topics",
        "_type": "Topic",
        "_id": "KL7KJ2QBWD77yvpxyjvd"
      },
      {
        "_index": "topics",
        "_type": "Topic",
        "_id": "374wJ2QBWD77yvpxDjpX"
      },
      {
        "_index": "topics",
        "_type": "Topic",
        "_id": "B7499GMBWD77yvpxFzgW"
      }
    ]
  }
  </code></pre>
  
  <p>Is there a way, in fluent NEST, to specify each index/type for each list of ids ?</p>
  
  <p>And of course if I'm adding specific ids to ids["Prod"] and ids["Account"] this will be generated properly for those... for instance: </p>
  
  <pre><code>http://localhost:9200/_mget?pretty=true
  {
    "docs": [
      {
        "_index": "topics",
        "_type": "Topic",
        "_id": "KL7KJ2QBWD77yvpxyjvd"
      },
      {
        "_index": "prods",
        "_type": "Prod",
        "_id": "xxxxx"
      },
      {
        "_index": "accounts",
        "_type": "Account",
        "_id": "yyyyy"
      }
    ]
  }
  </code></pre>