Questions tagged [mapping]
A type in solidity that allows access to arbitrary elements via a key, similar to a dictionary or hashmap in other languages.
521
questions
0
votes
1
answer
5
views
How much would be too much data to save in a public mapping?
So I know that in solidity for larger data we wouldn't use contract to save the data but rather we'd use some kind of external database.
But I'm not sure how large is too large and what would happen ...
0
votes
1
answer
11
views
What is the best gas efficient way to reset all values for keys in a mapping?
As far as I understand there is no way in solidity to automatically reset all values of a mapping to default in solidity. now lets say I have a mapping mapping with 7 keys and values set. to refresh ...
1
vote
1
answer
10
views
How to create a hash based on struct array types?
I have the following arguments to call a function in a smart contract:
ERC20Reward[] calldata _erc20Rewards
ERC721Reward[] calldata _erc721Rewards
ERC1155Reward[] calldata _erc1155Rewards
...
- 631
0
votes
1
answer
29
views
How to identify a specific ERC1155 token instance?
I'm trying to write a game item contract where the player can upgrade the items. For this, I need to be able to clearly distinct the different instances of the same tokenID.
Let me explain, if :
ID=0 -...
1
vote
1
answer
14
views
i have an upgradable smart contract with 3 mappings, i set only the first two in the initialize function
i have an upgradable smart contract with 3 mappings, i set only the first two in the initialize function .
pragma solidity ^0.8.0;
contract ContractA {
mapping(uint256 => address) public ...
- 328
1
vote
1
answer
92
views
What are the possible security threats when using mappings in Solidity?
Does the use of a nested mapping possess any threats to the security of the contract below?
contract Users {
struct User {
address payable regAddress;
uint64 timestamp;
...
- 202
0
votes
3
answers
38
views
How to access a mapping from another contract with enums
The second contract needs to check the mapping in the first contract to see if the person finished the required course. I checked a few old threads but they said it wasn't possibly with that version ...
- 1
0
votes
2
answers
10
views
Representing Price in a Mapping
I want to use a mapping that stores prices for each token in my ERC721 contract but am hitting an issue with the default uint value being 0. I'd like for my getPrice(uint256 tokenId) function to ...
- 123
0
votes
1
answer
34
views
Brownie not returning Mapping Values
Good day to everyone, I've been working with brownie for sometime now and have been running into a lot of challenges. I created a struct basically and a mapping to that struct, however when I deploy ...
- 3
1
vote
1
answer
25
views
How many strings can i store inside a mapping before the contract fails to work?
I have a single contract that is on the verge of its size limit (One more function and i wont be able to deploy anymore)
Within this contract, there is a mapping that I want to feed with strings after ...
- 47
0
votes
0
answers
14
views
Gas fees differ for updating different values?
I've did some gas efficiency tests on the testnet and wonder why the following is the case...
Updating values can be done with both of these methods:
x += y; /// or /// x = x + y;
For mappings, like ...
- 185
0
votes
0
answers
27
views
Is there any way to get the array length inside a mapping without a getter function or count variable?
mapping(address => uint256[]) public submitterAddressToFormIdsAssigned;
This is a mapping from an address to an array of uint256s.
I want to get the length of array. I used a count variable before ...
- 326
2
votes
1
answer
65
views
Storage collision in vyper hashmap?
Can you get a storage collision in vyper?
The HashMap value is stored at the keccack256 of the key.
So wouldn't this mean storage collisions are possible?
- 10.2k
0
votes
1
answer
15
views
Why we can't initial a public mapping in a struct?
contract MyContract {
struct Balance {
uint numDeposit;
mapping(address=> uint) public Deposit; //It will give an error due the public keyword
uint numWithdraw;
...
- 15
0
votes
2
answers
24
views
Initializing string variables from mapping values doesnt work
I try something like this:
mapping (uint256 =>string) public example;
then i initialze 'example' in the constructor
example[0]="apple";
example[1]="peach";
then i define a ...
- 47
1
vote
1
answer
766
views
Error encoding arguments: Error: types/values length mismatch (count={"types":1,"values":3}
Can you please explain me why it's happening and how I can solve it ?
Error:
call to GameItem.storeWalletAddress errored: Error encoding arguments: Error: types/values length mismatch (count={"...
0
votes
1
answer
63
views
Do keys in a map also packed to storage as well?
If we have this mapping
mapping(uint128 => uint256) private first;
mapping(uint128 => uint256) private second;
Do the keys of uint128 from both first and second gets stored together in one ...
- 1
1
vote
1
answer
21
views
Return a reference of map item from a function
Hello Solidity Community,
I have a chunk of code that repeats a lot, wondering if I could make a function or something to shorten it. Similar chunks of code appear a lot as well.
Skin memory skin = ...
- 27
1
vote
0
answers
17
views
How do I conduct Presale off chain? Keeping the address and the amount of coins purchased
I'm creating a presale website and a presale coin in solidity. How do I keep tract of the poeple who bought it something like whitelisting right
- 43
1
vote
1
answer
21
views
Dynamic update of struct field inside mapping
I have a struct
struct Shots{
uint coverDrive;
uint straightDrive;
uint pull;
uint squareCut;
}
and I used a mapping
mapping(address => Shots) public BattingSkill;
Now I want to ...
2
votes
1
answer
255
views
Gas limit for calling a smart contract function varies greatly upon address list parameter
Consider the following smart contract:
pragma solidity ^0.8.19;
contract Test {
mapping (address => bool) registered;
function test(address[] calldata addresses) external {
...
- 241
0
votes
1
answer
16
views
Variable Values do not persist in between function calls
I am new to Solidity, and I am experimenting on smart contracts using Remix-IDE connected to a deployed local Geth instance.
What I am trying to do is to create a struct containing multiple fields for ...
- 1
1
vote
1
answer
41
views
Gas cost of mapping operations
Suppose, your contract has something like
if (_balances[account] >= someNumber) {
_balances[account] = _balances[account] - _balances[account]/10;
}
What is the gas cost of this operation? I ...
- 111
0
votes
1
answer
67
views
Function isn't returning the uint256 value after initializing mapping
I'm facing a problem with the function return type in solidity. Here is my code:
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.17;
contract Birth {
mapping(uint256 => bool) public ...
1
vote
1
answer
117
views
Mapping String to uint
I'm trying to map string to uint but for some reason I'm not able to return the value. However on the demo contract it is working fine. Can somebody help me find the difference?
// SPDX-License-...
- 11
0
votes
0
answers
36
views
Using a nested mapping as a substitute of an mapping with array as value
I have an parent (address) which can have a collection of children linked to it. First I did this with a mapping of an address to a array of Children[] named parentToChildMapping. This was not really ...
- 126
0
votes
1
answer
18
views
Which one is gas efficient?
Lets say i want to store some data about each address ,through the mapping.
My first idea is: store in struct this way:
struct user {
address userAddress;
uint256 someUint:
string someString;
...
- 350
0
votes
0
answers
32
views
How to compare two values of structs of the same msg.sender from different mappings
I'm having a Smart Contract contest among friends about who loses the most weight. Each competitor is expected to enter its weight at the beginning of the week and at the end of the week. The ...
0
votes
1
answer
54
views
How to find all non zero mapping values?
This question is tightly related to how mappings are stored in the storage. Is there a way to search the storage and find all non-zero values of the mapping?
- 1,039
1
vote
1
answer
43
views
Using an Array to Delete Mappings
BEFORE YOU DOWNVOTE
I know questions on deleting mappings have come up thousands of times but I'd like to pose a question... can you delete it if it's in an array?
the following code allows the caller ...
- 282
0
votes
1
answer
50
views
Get mapping value with JSON-RPC → eth_getStorageAt || eth_call
How do I get mapping values from my contract with JSON-RPC (without using web3.js)?
In my contract:
struct Data {
address key;
string value;
}
mapping(bytes32 => Data) public values;
I can't ...
0
votes
1
answer
72
views
cost fee according to the size of a mapping
I try to improve my skills in solidity programming, for that i try to ode a dynamic NFT, which evolve according to 2 variables stored in a mapping.
struct NFTInfo {
uint32 nbOwners;
...
- 1
0
votes
2
answers
96
views
Storing address in a mapping
Is this code sufficient to store an address in a mapping?
mapping (address => bool) public registeredAddresses;
function register(address addr) public {
// check if Address hasn't been ...
- 133
2
votes
1
answer
84
views
Struct returns indexed numbers and property names
I'm using ethers and hardhat to run my React application. I want to pass an object as a parameter to a Solidity function. The function should map the object (struct) to the id provided as a property ...
0
votes
1
answer
222
views
Retreive a mapping nested inside a struct from Ethers
Hello Ethereum community,
I have couple of structs in my solidity code to organize things. Here is one struct from the code:
struct Staking {
uint total;
uint currentIndex;
mapping(address => ...
- 27
1
vote
0
answers
21
views
Why not repurpose mapping as array in solidity?
An array T[] can be implemented as a mapping(uint -> T) with indices acting as key in mapping and storing array length as separate uint.
I want to understand, if it is more gas efficient to use ...
- 11
0
votes
1
answer
183
views
ParserError: Source "@chainlink/contracts/src/v0.8/interfaces/AggregatorV3Interface.sol" not found: File outside of allowed directories
I'm trying to compile a "FundMe.sol" contract: the issue is that when I try to compile it I keep getting the following Compiler Error:
Brownie v1.19.2 - Python development framework for ...
0
votes
1
answer
100
views
Copying an array of structs to memory
I have some code that attempts to copy an array to mapping:
// Mapping of user addresses to their payment configuration
mapping(address => PaymentConfiguration[]) internal configurations;
// Event ...
- 271
0
votes
2
answers
31
views
How can I return multiple value?
How can I return multiple value.
If I get string ,it return the last value.
How to get string ,its return multiple value?
pragma solidity ^0.8.0 ;
contract Simple {
mapping(string => uint) ...
- 11
1
vote
1
answer
66
views
Unable to reach storage struct via mapping
Gm,
I've got a smart contract for 2D board game purposes. There is a struct Unit
struct Unit
{
UnitType unitType;
uint16 x;
uint16 y;
int8 hp;
int8 dmg;
...
- 21
0
votes
2
answers
27
views
Updating a struct property in an array stored as mapping value
This is my data structure for storing a list of questions which will be different for every address
struct Question{
uint16 id;
string question_string;
string answer;
}
and this is stored ...
0
votes
2
answers
59
views
Is this the right way to assign values to struct array with mapping?
struct userdata
{
string task;
bool isdone;
}
userdata[] public userinfo;
address public user;
// mapping (uint[]=>string) public tasksno;
mapping (address=>userdata[]) ...
0
votes
1
answer
177
views
Operator == Not compatible with types address[] storage ref and address
I have a mapping which maps uniqueids to an array of structs called Listing:
mapping(uint256 => Market.Listing[]) private _listings;
// the struct in the Market.sol
struct Listing {
address[] ...
- 153
0
votes
0
answers
47
views
Mapping or Struct to store data in NFT : gas fee and best practice
What is the best practice and gas less to store data inside the nft, not in metadata.
First exemple with 3 writes and second with 1 write.
But it seems Struct is more expensive. And when it will be ...
1
vote
2
answers
238
views
Delete an entry from mapping vs. setting it to zero
In most ERC721 setApprovalForAll() implementations, to revoke approval, the mapping is set to 0, instead of deleting the entry. I wonder what happens if many users have many approvals revoked, wouldn'...
- 115
1
vote
1
answer
96
views
How to loop through mapping in solidity with least gas cost possible?
I have a mapping defined in my contract like below.
mapping(address => uint256) public stakers
I need to loop through it to get all of them for my frontend and other contract.
function getStakers() ...
- 71
0
votes
1
answer
19
views
how can i use mapping on structure inside another structure and create some elements
i want to create some Pledges for Startup there are these structures:
struct Startup {
address payable founder;
string title;
string startupDescription;
uint goal;
uint ...
- 1
0
votes
1
answer
26
views
Mappings cannot be assigned to error Solidity
pragma solidity >=0.4.21 <0.7.0;
contract Bid{
mapping(string=>uint) propertyVoteCount;
mapping(string=>mapping(string => bool)) propertyUserVoted;
function vote(...
1
vote
1
answer
48
views
When declaring an Interface, do i have to declare the mappings of the contract too?
Actually im wondering if in order to use a mapping from a 3d party contract in an other contract, can i devlare the mapping in the interface and use it like Mycontract.mapping() and view/modifiy it ,...
- 45
0
votes
0
answers
21
views
Get next highest number / bidder in solidity
I am building an auction contract, every 7 days the highest bidder will get chosen and the non-winning bidders will participate for next week's auction.
My question is: lets say bidders sends bids in ...
- 289