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Mapping with iterating uint as identifier - multiple transactions in the same block

Struct not being stored in mapping when it contains more than two 'string' properties. Bug?Wrong value returned from functionDeploying a contract multiple times with the same LibraryThis contract does not implement all functions and thus cannot be createdProblems with mapping in soliditySolidity if condition based mapping with multiple structMapping address to multidimensional uintGas cost difference between uint[] and mapping(uint => uint)Multiple Array[] along with mapping handlingremix ERC223: This contract does not implement all functions and thus cannot be created

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1

I want to use an iterating uint as an identifying number, but I have a simple question to make sure I can do this safely on the mainnet. Here's a simple example to demonstrate the issue:

pragma solidity ^0.5.8;

contract Names 

 uint lastId;
 mapping(uint => string) public numberedNames;

 constructor() public 
 lastId = 0;
 

 function setName(string memory name) public 
 numberedNames[lastId] = name;
 lastId++;
 

My question is that if setName gets called multiple times within the same block, is it possible that lastId does not get updated after the first call, thus overriding the previous numberedNames element?

solidity mapping uint256

share|improve this question

asked 8 hours ago

SuperCodeBrahSuperCodeBrah

1556

add a comment | 

1

I want to use an iterating uint as an identifying number, but I have a simple question to make sure I can do this safely on the mainnet. Here's a simple example to demonstrate the issue:

pragma solidity ^0.5.8;

contract Names 

 uint lastId;
 mapping(uint => string) public numberedNames;

 constructor() public 
 lastId = 0;
 

 function setName(string memory name) public 
 numberedNames[lastId] = name;
 lastId++;
 

My question is that if setName gets called multiple times within the same block, is it possible that lastId does not get updated after the first call, thus overriding the previous numberedNames element?

solidity mapping uint256

share|improve this question

asked 8 hours ago

SuperCodeBrahSuperCodeBrah

1556

add a comment | 

I want to use an iterating uint as an identifying number, but I have a simple question to make sure I can do this safely on the mainnet. Here's a simple example to demonstrate the issue:

pragma solidity ^0.5.8;

contract Names 

 uint lastId;
 mapping(uint => string) public numberedNames;

 constructor() public 
 lastId = 0;
 

 function setName(string memory name) public 
 numberedNames[lastId] = name;
 lastId++;
 

My question is that if setName gets called multiple times within the same block, is it possible that lastId does not get updated after the first call, thus overriding the previous numberedNames element?

solidity mapping uint256

share|improve this question

asked 8 hours ago

SuperCodeBrahSuperCodeBrah

1556

pragma solidity ^0.5.8;

contract Names 

 uint lastId;
 mapping(uint => string) public numberedNames;

 constructor() public 
 lastId = 0;
 

 function setName(string memory name) public 
 numberedNames[lastId] = name;
 lastId++;
 

share|improve this question

asked 8 hours ago

SuperCodeBrahSuperCodeBrah

1556

share|improve this question

asked 8 hours ago

SuperCodeBrahSuperCodeBrah

1556

asked 8 hours ago

SuperCodeBrahSuperCodeBrah

1556

asked 8 hours ago

SuperCodeBrahSuperCodeBrah

1556

1 Answer
1

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votes

2

No, it doesn't matter whether transactions are in the same block or not. Each transaction is processed on its own, sequentially. The code you propose is fine, though an array may make more sense.

share|improve this answer

answered 8 hours ago

smarxsmarx

20.7k1820

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  In terms of an array making more sense, are you suggesting just to push the name onto the end of the array and use array indexes as as the identifier? Part of the reason I wanted to use a mapping is to allow for easier deleting. I'm not totally sure that I'll need to delete anything yet, but I'd think having to delete from an array while also maintaining the identifier would be messier.
  
  – SuperCodeBrah
  8 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Deleting from an array works the same way. delete foo[5] will just zero out the storage used by foo[5], regardless of whether foo is a mapping or an array.
  
  – smarx
  7 hours ago
  

  
  
  
  

add a comment | 

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2

No, it doesn't matter whether transactions are in the same block or not. Each transaction is processed on its own, sequentially. The code you propose is fine, though an array may make more sense.

share|improve this answer

answered 8 hours ago

smarxsmarx

20.7k1820

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  In terms of an array making more sense, are you suggesting just to push the name onto the end of the array and use array indexes as as the identifier? Part of the reason I wanted to use a mapping is to allow for easier deleting. I'm not totally sure that I'll need to delete anything yet, but I'd think having to delete from an array while also maintaining the identifier would be messier.
  
  – SuperCodeBrah
  8 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Deleting from an array works the same way. delete foo[5] will just zero out the storage used by foo[5], regardless of whether foo is a mapping or an array.
  
  – smarx
  7 hours ago
  

  
  
  
  

add a comment | 

2

No, it doesn't matter whether transactions are in the same block or not. Each transaction is processed on its own, sequentially. The code you propose is fine, though an array may make more sense.

share|improve this answer

answered 8 hours ago

smarxsmarx

20.7k1820

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  In terms of an array making more sense, are you suggesting just to push the name onto the end of the array and use array indexes as as the identifier? Part of the reason I wanted to use a mapping is to allow for easier deleting. I'm not totally sure that I'll need to delete anything yet, but I'd think having to delete from an array while also maintaining the identifier would be messier.
  
  – SuperCodeBrah
  8 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Deleting from an array works the same way. delete foo[5] will just zero out the storage used by foo[5], regardless of whether foo is a mapping or an array.
  
  – smarx
  7 hours ago
  

  
  
  
  

add a comment | 

No, it doesn't matter whether transactions are in the same block or not. Each transaction is processed on its own, sequentially. The code you propose is fine, though an array may make more sense.

share|improve this answer

answered 8 hours ago

smarxsmarx

20.7k1820

share|improve this answer

answered 8 hours ago

smarxsmarx

20.7k1820

answered 8 hours ago

smarxsmarx

20.7k1820

answered 8 hours ago

smarxsmarx

20.7k1820