solidity - Require() 函数在下面的代码中无法正常工作

Question

在 Rinkeyby 测试网络的 InjectedWeb3 环境中的 Remix IDE 上部署此合约。

我尝试删除 require 中的错误消息语句，然后它不会抛出错误，但仍然无法正常工作，即无论任何 require 条件如何，该函数都会被执行。

pragma solidity >=0.4.22 <0.7.0;
contract RegisterLand{

struct land{
     uint area;
     string location;
     uint floorsAllowed;
     mapping(uint => address) owner;
     uint count;
     bool idExists;
}
 mapping(uint => land) lands;
 function Register(uint id,uint area, string memory location, uint 
 floorsAllowed) public
 {
    require(
            !lands[id].idExists,
            "ID already exists"
             );
  lands[id] = land(area, location, floorsAllowed,0,true);
  lands[id].owner[lands[id].count] = msg.sender;
 }
 function ViewLand(uint id) public view returns(address currentOwner, 
 uint 
 landArea, string memory landLocation, uint landFloors )
 {
  require(lands[id].idExists,
         "Id doesn't exist.");
  currentOwner = lands[id].owner[lands[id].count];
  landArea = lands[id].area;
  landLocation = lands[id].location;
  landFloors = lands[id].floorsAllowed;
 } 
}

错误:

Failed to decode output: Error: overflow (operation="setValue", fault="overflow", details="Number can only safely store up to 53 bits", version=4.0.32)

Answer 1

有一个已知问题，要求 View /纯函数不会在公共(public)网络上恢复: https://forum.openzeppelin.com/t/require-in-view-pure-functions-dont-revert-on-public-networks/1211

如果您使用 Remix JavaScript VM，则使用不存在的 id 调用 ViewLand 会按预期恢复。

如果您对 dapp 开发有疑问，也可以在 OpenZeppelin 社区论坛中提问:https://forum.openzeppelin.com/

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