query_key option to return TRUE or FALSE on checks for stored key of certain type

[SamsungGalaxyPlayer]

There are many cases where servers may be used with a view key only to receive payments. Thus, it is useful to have functionality to be able to safely check through an RPC call if a wallet is view-only or not.

Related: https://monero.stackexchange.com/questions/10160/querying-wallet-rpc-about-whether-a-wallet-is-view-only

The RPC should allow an option to "check" for a given key_type if the particular key exists. The response should be TRUE or FALSE.

The RPC call should accept as an input a new optional parameter command with can be set to return (existing functionality) or check (true/false response).

This specific implementation is just an illustration of a possible method to meet the requirements of safely checking if a view-only wallet exists or not. The Monero devs (you) have a better idea of how it's best to implement.

[plowsof]

An error message will be returned if you query the spend key of a view-only wallet, so in a 'round about way' you can detect it by checking the response (which will be The wallet is watch-only. Cannot retrieve spend key.) but i guess a specific check wouldn't be too hard to implement , checks notes ah yes, i have zero c++ knowledge :D

curl -X POST http://192.168.1.68:18084/json_rpc -d '{"jsonrpc":"2.0","id":"0","method":"query_key","params":{"key_type":"view_key"}}' -H 'Content-Type: application/json'
{
  "id": "0",
  "jsonrpc": "2.0",
  "result": {
    "key": "f359631075708155cc3d92a32b75a7d02a5dcf27756707b47a2b31b21c389501"
  }
}

curl -X POST http://192.168.1.68:18084/json_rpc -d '{"jsonrpc":"2.0","id":"0","method":"query_key","params":{"key_type":"spend_key"}}' -H 'Content-Type: application/json'
{
  "error": {
    "code": -29,
    "message": "The wallet is watch-only. Cannot retrieve spend key."
  },
  "id": "0",
  "jsonrpc": "2.0"