How to set the value of a struct mapping to NULL?

Question

So, for example, if I have the following mapping in my Solidity code:

mapping (uint => myStruct) myMapping;

If let's say I have an object of this mapping. For example, myMapping[1] is mapped to a struct with certain values. But now I'd like myMapping[1] to be mapped to a NULL value or an empty myStruct.

How can I achieve this in my Solidity code?

Answer 1

You can try the code bellow. Just update the key with a blank structure. It will make the struct associated with the key to return to its default values.

pragma solidity ^0.8.0;

contract foo {

struct Test {
    uint myUint;
    string myString;
}

mapping(uint => Test) public myMapping;

function setMapping(uint key, uint _myUint, string memory _myString) public {
    Test memory test;
    test.myUint = _myUint;
    test.myString = _myString;
    myMapping[key] = test;
}

function nullifyStruct(uint key) public {
    Test memory test;
    myMapping[key] = test;
}


}

Answer 2

You can use the keyword delete

delete myMapping[key];