Save an array in mapping and get the value in Solidity

arraysmappingsolidity

I want to create a mapping with an array of values.
For example, I want to create a mapping of address that will hold the array of tokenIds that address holds.

0x0000XXXXX[0] = 989

0x0000XXXXX[1] = 121

Below is what I am trying in code:

struct Token {
    uint token;
}
mapping(address => Token[]) public addressMintedTokens;

function setTokens(_receiver, tokenId) internal {
addressMintedTokens[_receiver].push(tokenId);
}

Unfortunately, this is not working and giving an error
Member "push" not found or not visible after argument-dependent lookup in struct

Best Answer

To insert a key-value pair in your mapping, you can either use this syntax:

uint tokenId = 1729;
addressMintedTokens[_receiver] = Token({ token: tokenId });

Or this syntax:

uint tokenId = 1729;
addressMintedTokens[msg.sender].push(Token(tokenId));

Related Solutions

[Ethereum] How to initialize an empty array and push items into it

You need to use an array in storage because it is not possible to resize memory arrays.

contract D { 
    uint[] myArray;
    function Test() constant returns (uint[]) {
       myArray.push(123); 
       return myArray;
    }
}

Otherwise you need to define the size of the array during initialization:

contract C {
    function f(uint len) {
        uint[] memory a = new uint[](7);
        bytes memory b = new bytes(len);
        // Here we have a.length == 7 and b.length == len
        a[6] = 8;
    }
}

[Ethereum] How to create a simple fixed-size array

The fixed arrays doesn't have push member, you need to use the index to set the value:

pragma solidity ^0.4.24;

contract Garbage {
    address[3] public addresses;
    uint idx;

    function addAddress(address _address) public {
        require(idx < addresses.length);

        addresses[idx] = _address;
        idx++;
    }
}

Best Answer

Related Solutions

[Ethereum] How to initialize an empty array and push items into it

[Ethereum] How to create a simple fixed-size array

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