Add an extra flag in ES query to check if a field exists - elasticsearch

Question

I am writing a query to get some records like this:
curl -X GET 'http://localhost:9200/posts/post/_search?from=0&size=30&pretty' -d '{
"query": {
"filtered": {
"query": {
"query_string": {
"query": "content:(aid OR hiv)"
}
}
}
},
"fields": [
"content",
"entity_avatar_link",
"author_link",
"name"
],
size: 30,
from: 0
}
This much is working fine and I am getting the results.
I am trying to add a script field (which acts a flag) which returns whether a field exists in the doc along with every doc returned (I cannot return the field, as in most cases, it will be a very large size (an embedded field)). So, I added this also to the query:
"script_fields": {
"is_arranged_flag": {
"script": "!_source.arranged_retweets.empty"
}
}
So the whole query will be like:
curl -X GET 'http://localhost:9200/posts/post/_search?from=0&size=30&pretty' -d '{
"query": {
"filtered": {
"query": {
"query_string": {
"query": "content:(aid OR hiv)"
}
}
}
},
"fields": [
"content",
"entity_avatar_link",
"author_link",
"name"
],
"script_fields": {
"is_arranged_flag": {
"script": "!_source.arranged_retweets.empty"
}
}
size: 30,
from: 0
}
But after adding the script_fields section, no result is coming out (results is empty [] for the same search query).
I have also tried:
"script_fields": {
"is_arranged_flag": {
"script": "!doc['arranged_retweets'].empty"
}
}
What am I doing wrong?
Here is the mapping http://localhost:9200/posts/post/_mapping
{
"post": {
"properties": {
"arranged_retweets": {
"properties": {
"author_gender": {
"type": "string"
},
"author_link": {
"type": "string"
}
}
},
"content": {
"type": "string",
"analyzer": "tweet_analyzer"
},
"name": {
"type": "string",
"index": "not_analyzed",
"omit_norms": true,
"index_options": "docs"
},
"author_link": {
"type": "string",
"index": "not_analyzed",
"omit_norms": true,
"index_options": "docs"
},
"entity_avatar_link": {
"type": "string",
"index": "not_analyzed",
"omit_norms": true,
"index_options": "docs"
},
}
}
}

Answer 1

I think this is the valid script_fields segment.
"script_fields": {
"is_arranged_flag": {
"script": "!doc['arranged_retweets'].empty"
}
}
Reference: scripting (Read the section on document fields)

Answer 2

I figured it out with the help of the discussion here (https://groups.google.com/forum/#!topic/elasticsearch/BJZdlFSJSRg). The field arranged_retweets is an object. So, we need to check down to the inner level arranged_retweets.author_gender and check if it is empty like this:
"script_fields": {
"is_arranged_flag": {
"script": "!doc['arranged_retweets.author_gender'].empty"
}
}