Validate a $Location in Firebase

Question

I am trying to do some validation on incoming data into my firebase app. My structure is at the bottom. I have removed existing validation rules for clarity - however we can assume that reads and writes are allowed at the root rules level.

$categoryid will look something like this:

1234: {1:{...}, 2:{...}, 3:{...}}

I want to ensure that $categoryid (which is 1234 in the above example) is numerical - however the rule ".validate": "$categoryid.isNumeric()" results in an "no such method or property" error.

I could check for data.child($categoryid) in categories, however the variable doesn't exist at that level and results in an "unknown variable" error.

I'm sure I'm missing a trick here...

{
  "rules": {   
    "categories": {
      "$categoryid": {
        "$itemid": {
          "members": {
            "$id": {

            }
          }
        }
      }
    }
  }
}

Answer 1

There is currently no good way to do this, but there is a hacky work around that involves storing the $categoryId in a field, then checking that that field is numeric.

Using these security rules:

{
  "rules": {   
    "categories": {
      "$categoryid": {
        ".validate": "'' + newData.child('meta/id') === $categoryId && newData.child('meta/id').isNumber()"
        "meta": {},
        "items": {
          "$itemid": {
            "members": {
              "$id": {

              }
            }
          }
        }
      }
    }
  }
}

We can then create a new category by running:

categoriesRef.child(1234).set({meta: {id: 1234}});

These rules will check that a) the $categoryId matches $categoryId/meta/id and that $categoryId/meta/id is a number.

Answer 2

To do this validation you can use RegEx /^[0-9]+$/

{
   "rules": {   
    "categories": {
     "$categoryid": {
        .validate": "$categoryid.matches(/^[0-9]+$/)"
       "$itemid": {
         "members": {
           "$id": {

           }
         }
      }
     }
  }
 }
}