Type error: memory is not implicitly convertible to expected type

Question

I have a function that returns a list of BetProposition smart contracts:

function getBetsForMatchup(uint matchupIdentifier) public returns (BetProposition[]) {
        return bets[matchupIdentifier];
    }

Later I initialize a local variable array as such, so I can loop through them:

   BetProposition[] betsToCancel = getBetsForMatchup(matchupIdentifier);

However, this doesn't seem to work and I get this error:

TypeError: Type contract BetProposition[] memory is not implicitly convertible to expected type contract BetProposition[] storage pointer.
    BetProposition[] betsToCancel = getBetsForMatchup(matchupIdentifier);
    ^------------------------------------------------------------------^

I'm not totally sure what this means. Any help appreciated. Thanks

Answer 1

The compiler thinks you are trying to store the return value of getBetsForMatchup in contract (permanent) storage.

Try changing

   BetProposition[] betsToCancel = getBetsForMatchup(matchupIdentifier);

to

   BetProposition[] memory betsToCancel = getBetsForMatchup(matchupIdentifier);

This compiled on remix:

   pragma solidity ^0.4.20;
   contract BetProposition {
       uint public somevar;

       function BetProposition(uint _some) public {
         somevar = _some;
       }
   }

   contract Tester2 {
        mapping(uint => BetProposition[]) bets;

        function getBetsForMatchup(uint matchupIdentifier) public view returns (BetProposition[]) {
            return bets[matchupIdentifier];
        }

        function other(uint matchupIdentifier) public view returns(uint) {
             uint total = 0;
             BetProposition[] memory betsToCancel = getBetsForMatchup(matchupIdentifier);
             for (uint i = 0; i < betsToCancel.length; i++) {
                 total = total + betsToCancel[i].somevar();
             }
             return total;
        }
}