Mapping issue #19 #26

johnfawole · 2022-09-29T13:01:08Z

This is the submission of issue #19. Please, let me know if you have any edits.

I look forward to hearing from you.

issue chainstacklabs#19 Co-Authored-By: Priyank Gupta <priyankgupta0308@gmail.com>

Genesis3800 · 2022-10-12T18:46:21Z

info-articles/Mapping in solidity - issue #19.md/article.md

+
+   goerli: {
+
+     url: `https://eth-goerli.alchemyapi.io/v2/${Chainstack_API_KEY}`,


Hey John,
The Goerli URL needs to change in terms of format. I appreciate using the Chainstack_API_KEY const in the URL,
but the overall URL needs to look like this-
https://nd-123-456-789.p2pify.com/$${Chainstack_API_KEY}

We can't use a URL with 'alchemy' in it on our blog.

Genesis3800 · 2022-10-12T18:55:42Z

info-articles/Mapping in solidity - issue #19.md/article.md

+mapping(address => mapping(address => uint)) public allowance; 
+```
+The mapping above is a nested one that involves two sets of addresses where one allows or approves the other to take a specific action.
+3. ### Identifying owners


This line doesn't render correctly while viewing the file. Attaching an SS.

Genesis3800 · 2022-10-12T18:58:30Z

info-articles/Mapping in solidity - issue #19.md/article.md

+## How Mappings Are Stored in Solidity
+Mapping in itself is not capable of storing data. The only extent to which they are helpful in helping us tie some key types to value types. This is why you will discover that you cannot get the “.length” of mappings because they do not store actual data in real-time.
+
+But while it does not store data, we will need the hash of the key to trace its value pair. The hashes are stored in the storage slots of the contract. As a result, mappings can only declared at the state level and should be stored in storage; not calldata or memory. 


Nice explanation.

Genesis3800 · 2022-10-12T19:10:30Z

info-articles/Mapping in solidity - issue #19.md/article.md

+     theBalanceOf[msg.sender] = 3 ether;
+    }
+```
+### Getting Mapping


Nice little section. I feel one more thing could be added.
We don't have to always assign mapping value to a new variable to get a mapping. We can also simply return a mapping value from a function without using another variable.

Something like this-

function gettingMapping2() external view returns(uint){
return theBalanceOf[msg.sender];
}

Genesis3800 · 2022-10-12T19:12:33Z

info-articles/Mapping in solidity - issue #19.md/article.md

+## How to Work with Arrays in Mapping
+There is a slight variation when you have strings of arrays as the value type of your mapping, especially when it is a dynamic array. In such instances, be mindful of your parameters.
+```
+ contract MappingArrays{


This code snippet has a missing closing parenthesis } in the end

Suggested change

contract MappingArrays{

contract MappingArrays{

```suggestion

contract MappingArrays{

Genesis3800 · 2022-10-12T19:18:54Z

info-articles/Mapping in solidity - issue #19.md/article.md

+
+The next stage is to compile and deploy this contract using Hardhat. Perhaps you have not installed Hardhat in your terminal; paste this on your terminal:
+```
+nvm install latest


Hey @johnfawole,

This command is used to install node through nvm, this is NOT the command to install hardhat from the command line.

Changed it to - npm install — save-dev hardhat

Genesis3800 · 2022-10-12T19:20:40Z

info-articles/Mapping in solidity - issue #19.md/article.md

+```
+For the compilation, run this command:
+```
+npx hardhat compile


The readers should be told where they should paste their code. Hardhat has an src folder in their root directory where contracts are written.

Genesis3800 · 2022-10-12T19:21:36Z

info-articles/Mapping in solidity - issue #19.md/article.md

+```
+npx hardhat compile
+```
+Bear in mind that you should not have put on the auto-compile option on Remix. Or else, the CLI will return that there is nothing to compile.


I don't understand this one. How is remix related here? Are you somehow working with remix through the CLI?

Yes, but for convenience, I have deleted it and suggested doing this on Vs Code terminal instead.

Genesis3800 · 2022-10-12T19:22:24Z

info-articles/Mapping in solidity - issue #19.md/article.md

+```
+Bear in mind that you should not have put on the auto-compile option on Remix. Or else, the CLI will return that there is nothing to compile.
+
+Once that is successful, deploy it to your favorite testnet using the Chainstack Ethereum URL. First, create a file in deploy.js and run this script:


This is not a deploy script. This is the configuration that goes inside the hardhat.config file. This isn't how a deploy script goes.

Genesis3800 · 2022-10-12T19:23:29Z

info-articles/Mapping in solidity - issue #19.md/code/readme.md

+
+You will need Hardhat for the compiling and deployment. Run this on your terminal
+```
+nvm install latest


This is a command to install the latest version of node, this doesn't install hardhat.

Genesis3800 · 2022-10-26T14:21:23Z

info-articles/Mapping in solidity - issue #19.md/article.md

+
+The next stage is to compile and deploy this contract using Hardhat. Go to the Hardhat folder on your device, locate the src folder and write your contract there. Perhaps you have not installed Hardhat in your terminal, paste this on your Vs Code terminal:
+```
+npm install — save-dev hardhat


npm install --save-dev hardhat is the correct command to install hardhat. I think you made a spelling mistake here. The section to install hardhat needs to include the process to create a new hardhat project using their in-terminal UI.
We can install ethers and other required libraries without running an extra command, by using npx hardhat command to set up a basic javascript project.

Yes, it was a typo. Corrected it now.

Genesis3800 · 2022-10-26T14:25:59Z

info-articles/Mapping in solidity - issue #19.md/article.md

+
+This contract is a simple wallet contract where users can deposit, transfer, and know the remaining Ethers in the contract. Here, we used mapping to track both balances and allowance.
+
+The next stage is to compile and deploy this contract using Hardhat. Go to the Hardhat folder on your device, locate the src folder and write your contract there. Perhaps you have not installed Hardhat in your terminal, paste this on your Vs Code terminal:


I don't think there is an src folder in hardhat anymore. The smart contract needs to go under the 'contracts' folder.

Yes, yes, discovered that too.

Genesis3800 · 2022-10-26T14:37:03Z

info-articles/Mapping in solidity - issue #19.md/article.md

+
+};
+```
+The final step is to write a deployment script. Create a deploy.js file where you will write your deployment script - you can choose either Javascript or Typescript. When you are done, start a node:


You don't need to start a node to deploy a contract, a mock blockchain is used to test contracts, not to deploy them

Deleted it since it is a test project. Thanks.

Genesis3800 · 2022-10-26T14:37:36Z

info-articles/Mapping in solidity - issue #19.md/article.md

+```
+npx hardhat node
+```
+Then you can deploy to a testnet:


First a deploy script specific to the contract needs to be written to deploy a contract before calling the script.

Indicated that.

This is the final draft, I have added the deployment script as instructed. Do consider merging the PR. Thanks

johnfawole and others added 7 commits September 29, 2022 13:37

Mapping article

69c635b

issue chainstacklabs#19 Co-Authored-By: Priyank Gupta <priyankgupta0308@gmail.com>

Update code.sol

00e12c8

Update code.sol

524f2c0

Update About.md

582615f

Add files via upload

e0f805b

Update article.md

cf59626

Update readme.md

d3c28b0

Genesis3800 suggested changes Oct 12, 2022

View reviewed changes

johnfawole added 3 commits October 14, 2022 11:36

Update article.md

d4fff0d

Update readme.md

c5ebd90

Update article.md

864df0a

Genesis3800 suggested changes Oct 26, 2022

View reviewed changes

johnfawole added 2 commits November 11, 2022 08:10

Update article.md

a57f941

Added the deployment script

9ff6a7d

This is the final draft, I have added the deployment script as instructed. Do consider merging the PR. Thanks

Genesis3800 merged commit aa29b0d into chainstacklabs:master Dec 19, 2022


		goerli: {

		url: `https://eth-goerli.alchemyapi.io/v2/${Chainstack_API_KEY}`,


		This contract is a simple wallet contract where users can deposit, transfer, and know the remaining Ethers in the contract. Here, we used mapping to track both balances and allowance.

		The next stage is to compile and deploy this contract using Hardhat. Go to the Hardhat folder on your device, locate the src folder and write your contract there. Perhaps you have not installed Hardhat in your terminal, paste this on your Vs Code terminal:

Mapping issue #19 #26

Mapping issue #19 #26

Uh oh!

Conversation

johnfawole commented Sep 29, 2022

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants