How to save complex object in the contract in solidity

0 votes

I have this use case where I need to persist the following sample data in my contract.

{
    Linkage : {"4" : "1", "77" : "59", "5" : "64", "4" : "464", "455" : "364", "25" : "364", "25" : "164", "55" : "8684", "85" : "864"},
    UserId : "Some Id",
}

The dictionary is obviously expandable (root And Linkage). I want to send the data and retreive it as an object (c# and Java style). So when I communicate from WEB3 I can pass json. Is that possible?

This is where I got stuck...

pragma solidity ^0.4.13;

contract Test{         
  struct UserProfile{       
    string UserId;
  }   

  UserProfile public Profile;

  function setProfile(UserProfile newProfile) public {
    Profile  = newProfile;
  }        
}
Oct 15, 2018 in Blockchain by slayer
• 29,350 points
3,324 views

1 answer to this question.

0 votes

You can't pass objects when initiating a transaction (yet). You can only pass in/return a structthrough internal function calls (see Solidity FAQ).

You'll have to pass in your data using primitive types and add them to your internal struct:

pragma solidity ^0.4.13;

contract Test { 
  struct UserProfile {
    string userId;
    mapping(uint256 => uint256) linkage;
  }   

  UserProfile public profile;

  function addLinkage(uint256 id, uint256 value) public {
    profile.linkage[id] = value;
  }
}

Note, if you want to pass in your linkages in bulk, you can use addLinkage(uint256[] ids, uint256[] values).

answered Oct 15, 2018 by Omkar
• 69,210 points

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