How to search parent document without children?

[Lyudmila_Fokina]

Try this one (worked for me);
{
"query": {
"bool" : {
"must" : [ {
"bool" : {
"must_not" : {
"has_child" : {
"type": "child",
"query": {
"match_all": {}
}
}
}
}
},
{
"match": {
"relation_type": "parent"
}
}]
}
},
"size": 10
}