I am creating the following contract:

pragma solidity ^ 0.4.17;

contract TodoList {

    event NewTodo(uint todoId, string value);
    event DeleteTodo(uint todoId, string value);

    mapping(uint => address) public todoOwner;
    mapping(address => uint) ownerTodoCount;

    TodoItem[] public todoItems;

    struct TodoItem {
        string value;
        //TODO submit ether to a TodoItem
        bool active;

    function createTodo(string _value) internal returns(uint) {
        uint id = todoItems.push(TodoItem(_value, true)) - 1;
        todoOwner[id] = msg.sender;
        NewTodo(id, _value);
        return id;

    function getAllTodos() constant returns(string[], bool[]) {
        uint length = todoItems.length;

        string[] memory values = new string[](length);
        bool[] memory actives = new bool[](length);

        for (uint i = 0; i < length; i++) {
            values[i] = todoItems[i].value;
            actives[i] = todoItems[i].active;

        return (values, actives);

I would like to display all todos by a user. For this I created the getAllTodos function.

However, when doing truffle compile I get the following error:

UnimplementedFeatureError: Nested dynamic arrays not implemented here.

Any suggestions how to access all todos?

1 Answer 1


So dynamic nested arrays are something not perfectly handled by solidity as of now. Every time you access a function involving a nested array, it must be internal. Thus, I am guessing the error could be in function getAllTodos whose access scope isn't specified, thus defaulting to public.

I hope this works! (PS- I have heard that this could also fail because nested arrays isn't fully implemented yet, but well worth a try

  • Thx for your reply! Would you be so kind to add a sample code, how to do it better? I guess this might be highly relevant for future "answer" searchers.
    – Carol.Kar
    Feb 2, 2018 at 5:26
  • So I think the code could work if you have the following function definition: function getAllTodos() internal returns(string[], bool[]) Feb 2, 2018 at 15:31

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