[Ethereum] How to handle dynamic size string array in solidity

I have a shop owner and a shop owner can have multiple products. I want to keep the products id in an array.

Also, A public method can return all the product id list of a shop owner.

I tried the following code

pragma solidity 0.5.0;

contract Shop {

    struct ShopOwner {
        string id;
        string[] productList;
    }

    struct Product {
        string id;
        string name;
    }

    mapping(string => ShopOwner) private mapShopOwner;

    function getUserProductList(string _shopOwnerId) public view returns(string[]) {
        return (mapShopOwner[_shopOwnerId].productList);
    }

}

This seems does not support the solidity language.

I am getting the error

browser/Structure.sol:17:33: TypeError: Data location must be "memory"
for parameter in function, but none was given.
function getUserProductList(string _userId) public view returns(string[]) {
^————^

and

browser/Structure.sol:17:69: TypeError: Data location must be "memory"
for return parameter in function, but none was given.
function getUserProductList(string _userId) public view returns(string[]) {
^——^

And I do not want to use pragma experimental ABIEncoderV2;

I wonder, what is the correct procedure to handle this types of relation.