I encouter little problems using mix. I have the following contract-code:

contract C {
    function C() {}

    struct S {
        address creator;

    mapping(string => S) M;
    uint x;

    function set(string _hash) {
        S memory N = S({
            creator : msg.sender

        M[_hash] = N; //I dont see the mapping in Mix
        x = _hash; //I see 'x' in the current state with the correct value

    function get(string _hash) returns (address addr) {
        return M[_hash].creator;

The problem is that I do not see the current state of the contract in the bottom right corner of the IDE. While I see x and the value of _hash, I do not see the state of the mapping(string => S), which should be in the variable M

I thought the mapping maybe is just empty after calling, but when I call the get-function, It returns the correct address from the sender before.

Does anyone had the same issue before or can help me with this?

1 Answer 1


Mappings work by hashing the key to get the storage address and so the keys themselves aren't stored. Unless keys can be provided, such as in a seperate lookup table, there is no simple way to view the contents of a mapping so Mix simply doesn't show them.

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