Firebase Security Rules: .indexOn unique ids

Question

I have this structure:

\"post\": {
   \"groupMember\": {
     \"-KHFHEHFWDB1213\": \"true\",
     \"-KSJHDDJISIS011\": \"true\",
     \"-KJSIO19229129k\": \"tru         


        

Answer 1

To query whether or not one of the given keys has value "true" (note that as typed your data structure is a string, not a boolean -- something to look out for!) you'll want to create security rules like so:

{
  "post": {
    "groupMember": {
      "$memberId": {".indexOn": ".value"}
    }
  }
}

And then use queryOrderedByValue("true") on the /post/groupMember path. Important to note is $memberId in the rules, which declares a wildcard key representing your autogenerated ids, and .value, which indicates that rather than indexing on a child property (if your structure had another layer of nesting) you want to index on the immediate leaf node value.