Solidity Structs – How to Initialize a Struct with an Empty Array

The other answer which didnt work brought me on track to find it out myself:

contract testStruct {
    struct stru{
        string[] s;
    }

    stru myStru;

    function add(string s) {
        myStru.s.push(s);
    }

    function getAt(uint256 i) constant returns (string s) {
        s = myStru.s[i];
    }
}

I encountered the exact same problem when I was trying to implement a very similar smart contract. Ultimately, I ended up changing my design pattern. Solidity doesn't yet support initialization of a struct array from memory when trying to write to a storage array in a struct. Hopefully this will be supported in the future because it's quite limiting.

My workaround was opting for this design pattern, where the array of structs is declared outside of the struct itself. I then just map each address to that struct array. It's not pretty, but it does work.

address[] internal addresses;
mapping(string => address) internal names;
mapping(address => Profile) public profiles;
mapping(address => mapping(address => Profile)) internal followers;
mapping(address => mapping(address => Profile)) internal following;
mapping(address => Post[]) internal posts;

// Profile
struct Profile {
    address owner;
    string name;
    uint timeCreated;
    uint id;
    uint postCount;
    uint followerCount;
    uint followingCount;
    address[] followers;
    address[] following;
}

// Post
struct Post {
    address author;
    string content;
    uint timeCreated;
    uint id;
}

You can find my full implementation here:

https://gist.github.com/charlesalexanderlee/c97d6169c9d65d03d74bb25a07d442e1