how to combine parent and children from Solr nested documents - solr

Question

I'm new on lucence, solr queries, I have doubts about how to make a query to nested documents.
I have nested document indexed, as below
[
{
"id": "1",
"title": "Solr1",
"_childDocuments_": [
{
"id": "2",
"title": "Solr2",
"_childDocuments_": [
{
"id": "3",
"title": "Solr3",
"_childDocuments_": [
{
"id": "4",
"title": "SolrCloud supports it"
}
],
"something_else":"irrelevant"
}
],
"something_else":"irrelevant"
}
],
"something_else":"irrelevant"
},
{
"id": "5",
"title": Solr5",
"_childDocuments_": [
{
"id": "6",
"title": "SolrCloud here as well"
}
]
}
]
How do I search title:SolrCloud, and listed all children's parents? Such as
[
{
"id": "1",
"title": "Solr1",
"_childDocuments_": [
{
"id": "2",
"title": "Solr2",
"_childDocuments_": [
{
"id": "3",
"title": "Solr3",
"_childDocuments_": [
{
"id": "4",
"title": "SolrCloud supports it"
}
]
}
]
}
]
},
{
"id": "5",
"title": Solr5",
"_childDocuments_": [
{
"id": "6",
"title": "SolrCloud here as well"
}
]
}
]
which listed all parents of document 4(Sorl1, Solr2, Solr3) and document 6(Solr5).
And the depth of documents is not constants.

Answer 1

My current solution is that massaging data, add trace into original data, so I will know document come from. such as
[
{
"id": "1",
"title": "Solr1",
"_childDocuments_": [
{
"id": "2",
"title": "Solr2",
**"parent_id":"1",**
**"trace":"Solr1",**
"_childDocuments_": [
{
"id": "3",
"title": "Solr3",
**"parent_id":"2",**
**"trace":"Solr1/Solr2",**
"_childDocuments_": [
{
"id": "4",
"title": "SolrCloud supports it"
**"parent_id":"3",**
**"trace":"Solr1/Solr2/Solr3",**
}
],
"something_else":"irrelevant"
}
],
"something_else":"irrelevant"
}
],
"something_else":"irrelevant"
},
{
"id": "5",
"title": Solr5",
"_childDocuments_": [
{
"id": "6",
**"parent_id":"5",**
**"trace":"Solr5",**
"title": "SolrCloud here as well"
}
]
}
]
So after indexed, I could know who's parent document from result.
Could someone agree on this?
Looking for better solution than this.