Need this architecture

      address1 => [struct1, struct2],
      address2 => [struct1, struct2, struct3,],
      address3 => [struct1, struct2, struct3, struct4, struct5],

My Attempt

// SPDX-License-Identifier: GPL-3.0
pragma solidity ^0.8.0;

contract Owner {

    uint private _ids;

    struct UserDetails {
        uint256 id;
        string title;

    mapping (address => UserDetails[]) public users;
    mapping (address => uint256) public userDetails; 

    function createPost(string memory _title) public {
        _ids ++; 
        uint256 _users = users[msg.sender].push(UserDetails(_ids, _title)); 
        userDetails[msg.sender] = _users;

but i cant push struct into the mapping, it's showing me error:

TypeError: Different number of components on the left hand side (1) than on the right hand side (0).

please help ;)

1 Answer 1


Just remove uint256 _users = in the createPost() so that uint256 _users = users[msg.sender].push(UserDetails(_ids, _title)); becomes users[msg.sender].push(UserDetails(_ids, _title));

  • but i want to save this in a variable. uint256 _users = users[msg.sender].push(UserDetails(_ids, _title)); userDetails[msg.sender] = _users; i want to achieve this basically Mar 9, 2022 at 9:24
  • please have look on my question again, i edited my code. Mar 9, 2022 at 9:26
  • So what I understand is that you are trying to keep number of elements from the struct array in userDetails mapping. if that is the case then function createPost(string memory _title) public { _ids ++; users[msg.sender].push(UserDetails(_ids, _title)); userDetails[msg.sender] = users[msg.sender].length; } Mar 9, 2022 at 9:41
  • Thanks mate, it worked. Thank u :) Mar 9, 2022 at 9:43
  • I am glad. Cheers :) Mar 9, 2022 at 9:45

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