How can I return dynamic string array in Solidity?

Question

How can I return a dynamic string array? I came across serialization and deserialization. How can I serialize and deserialize dynamic string array ?

pragma solidity ^0.5.0;

contract Abc{
    string[] st;

    function add(string memory newValue) public {
        st.push(newValue);
    }

    // return st

Answer 1

As of Solidity 0.7.5 the ABIEncoderV2 is not experimental anymore and can be selected using the pragma directive.

This gives native support for returning dynamic string arrays from functions.

pragma solidity ^0.8.2;
pragma abicoder v2;

contract Abc {
    string[] st;

    function add(string memory newValue) public {
        st.push(newValue);
    }

    function getSt() public view returns (string[] memory) {
        return st;
    }
}

On a side note, starting with Solidity 0.8.0 abicoder v2 is enabled by default and the pragma directive can therefore be omitted.

Answer 2

Actually there is not support from solidity for returning an array of strings as described here:

Return dynamic array of string

You can fix it adopting this workaround described here:

Deserialize a string

Answer 3

You need to use ABIEncoderV2:

pragma experimental ABIEncoderV2;

contract Foo {
  string [] private strings;

  function addString (string memory str) public {
    strings.push (str);
  }

  function getStrings () public view returns (string [] memory) {
    return strings;
  }
}

See documentation for details.