How to add resource and specify related element? - rest

Question

I have a simple API for a game tip website:
/class is the endpoint for in game classes
/tip is the endpoints for the tips
/user is the endpoint for the users
Each tip has 3 relations:
(:User)-[:AUTHORED]-(:Tip)
(:Class)<-[:FOR]-(:Tip)
(:Class)<-[:AGAINST]-(:Tip)
When I create a Tip using POST, I do'nt know how to add relations at the create time.
I can do this way: Add relation to another node in SDN4 + REST after creating the resource, but I want to do it with only one query.
EDIT:
I tried to POST this:
'{"content":"TEST", "forClass":"/class/2", "againstClass":"/class/2"}'
and the item has been created, no InvalidArgument Exception raised, but if I go to my class resource's tips, I don't have any tips:
GET /class/2/tips:
{
"_embedded" : {
"tip" : [ ]
},
"_links" : {
"self" : {
"href" : "http://localhost:8080/class/2/tips"
}
}
}
GET /tip/9 (the created one):
{
"content" : "TEST",
"_links" : {
"self" : {
"href" : "http://localhost:8080/tip/9"
},
"tip" : {
"href" : "http://localhost:8080/tip/9"
},
"author" : {
"href" : "http://localhost:8080/tip/9/author"
},
"againstClass" : {
"href" : "http://localhost:8080/tip/9/againstClass"
},
"forClass" : {
"href" : "http://localhost:8080/tip/9/forClass"
}
}
}
GET /tip/9/forClass:
{
"name" : null,
"_links" : {
"self" : {
"href" : "http://localhost:8080/class/2"
},
"bnSClass" : {
"href" : "http://localhost:8080/class/2"
},
"tips" : {
"href" : "http://localhost:8080/class/2/tips"
}
}
}