Storing image URLs in Solidity

Question

I have a very basic but functional smart contract which stores an image URL (and some other fields) for front-end use. However, while it works with shortened image URLs, most URLs are too long, causing the gas costs to skyrocket beyond the block gas limit.

Is there a more efficient way to store the URLs, or would I need to automatically shorten them somehow before sending them to the back-end?

For some context, here is my contract (As mentioned, very basic):

contract Advertisement {
    string private image_url = "https://via.placeholder.com/350";
    string private text = "Placeholder text";
    uint private price = 0; // First user can upload their image for free (+gas);

    function updateAdvertisement(string memory new_image, string memory new_text) public payable {
        require(msg.value > price, "Payment must be greater than the listed price");
        
        image_url = new_image;
        text = new_text;
        price = msg.value;
    }

    function getAdvertisement() public view returns(string memory, string memory, uint) {
        return (image_url, text, price);
    }
}

Answer 1

If you would like to store the url data decentralized then IPFS is a good way to go.

If you just want to use the url to display something and use it off-chain (backend). Instead of returns the real url, you can returns the id of the url, the backend can look from db for the url based on that id.