Elastic Search: General and Conditional Filters

I am using Elastic Search, with a match_all query and filtering. In my situation, I want to apply general filter and conditional filters.

Here in pseudo:

• query: match all (works fine)
• filter selection period between d1 and d2 (works fine without bullet 3)
• filter (only applies if the field exists, but how?)
• and etc.

See the following code. I want to apply the "groups" filter only if the "groups" field exists! The filter "exists" does not take effect in this case.

    "query":
    {
        "filtered":
        {
            "query":
            {
                "match_all": {}
            },
            "filter":
            {
                "bool":
                {
                    "must":
                    {
                        "range":
                        {
                            "date": {
                                "from": "2015-06-01",
                                "to": "2015-06-30"
                            }
                        }

                    },
                    "must_not":
                    {
                        "term":
                        {
                            "e.state": 0
                        }
                    }
                }
            },
            "filter":
            {
                "bool":
                {
                    "must":
                    {
                        "exists": {"field": "groups"},
                        "filter":
                        {
                            "bool":
                            {
                                "must":
                                {
                                    "term": {"groups.sex": "w"}
                                },
                                "should":
                                {
                                    "terms": {"groups.categories.id": [7,10]}
                                }
                            }
                        }
                    }
                }
            }
        }
    }
}