如何使用R和JSON保留Etherscan API的換行符？

Question

我正在使用Etherscan API下載某些已驗證合同的Solidity代碼。 盡管這樣做確實有效，但我丟失了需要保留的換行符。

例如，考慮https://etherscan.io/address/0xb494e1195e0c6bad435be4c9fa0b36ce94bfd7d1#code上已驗證合同的代碼

該合同的Solidity代碼片段為：

pragma solidity ^0.4.18;

/**
 * @title SafeMath
 * @dev Math operations with safety checks that throw on error
 */
library SafeMath {
  function mul(uint256 a, uint256 b) internal pure returns (uint256) {
    uint256 c = a * b;
    assert(a == 0 || c / a == b);
    return c;
 }
 function div(uint256 a, uint256 b) internal pure returns (uint256) {
    // assert(b > 0); // Solidity automatically throws when dividing by 0
    uint256 c = a / b;
    // assert(a == b * c + a % b); // There is no case in which this doesn't hold
   return c;
 }
more code....

最終，我希望將Solidity代碼存儲為包含換行符的字符串，即我想要

str_a <- "pragma solidity ^0.4.18;\\n\\n/**\\n* @title SafeMath\\n* @dev Math operations with safety checks that throw on error\\n*/\\nlibrary SafeMath {\\nfunction mul(uint256 a, uint256 b) internal pure returns (uint256) {\\nuint256 c = a * b;\\nassert(a == 0 || c / a == b);\\nreturn c;\\n}\\nfunction div(uint256 a, uint256 b) internal pure returns (uint256) {\\n// assert(b > 0); // Solidity automatically throws when dividing by 0\\nuint256 c = a / b;\\n// assert(a == b * c + a % b); // There is no case in which this doesn't hold\\nreturn c;\\n}"

但是，我編寫的代碼會產生

pragma solidity ^0.4.18;/** * @title SafeMath * @dev Math operations with safety checks that throw on error */library SafeMath { function mul(uint256 a, uint256 b) internal pure returns (uint256) { uint256 c = a * b; assert(a == 0 || c / a == b); return c; } function div(uint256 a, uint256 b) internal pure returns (uint256) { // assert(b > 0); // Solidity automatically throws when dividing by 0 uint256 c = a / b; // assert(a == b * c + a % b); // There is no case in which this doesn't hold return c; }

我的產生輸出的代碼如下，其中gstr_api_key是在代碼前面定義的表示API密鑰的全局字符串：

str_address <- "0xb494e1195e0c6bad435be4c9fa0b36ce94bfd7d1"

# Build string needed for URL
str_APIAction <- "/api?module=contract&action=getsourcecode&address="
str_APIKey <- paste("&apikey=", gstr_api_key, sep="")
str_path <- paste(str_APIAction, str_address, str_APIKey, sep="")

# Send request to API
raw_result <- httr::GET(url = gstr_eth_url, path = str_path)

# Convert response in to useful 
raw_char <- rawToChar(raw_result$content)
raw_list <- jsonlite::fromJSON(raw_char)

str_a <- raw_list$result[1] 

我對JSON格式的了解有限，但我知道JSON中不允許換行符。 那是對的嗎？

如何修改代碼，以便獲得所需的輸出？

Answer 1

我已經解決了問題-無法使用API​​完成。 而是使用httr和XML庫抓取頁面。 最后很容易