如何从带有未转义反斜杠的JSON文件读取？ [英] How to read from a JSON file with unescaped backslashes?

问题描述

我有一个包含连接字符串的JSON文件：

I have a JSON file that contains a connection string:

abc.json

{
  "host":"1.2.3.4",
  "user":"abc",
  "passwd":"s&]\yz$&u42/",
  "dbname":"sample",
  "port":2341
}

这是我的Python脚本尝试读取数据：

Here's my Python script which tries to read the data:

 import psycopg2 as pg
 dbconn = "C:\abc.json"
 with open(dbconn) as conn_file:
     conn = json.load(conn_file)

它给了我这个错误：

json.decoder.JSONDecodeError: Invalid \escape: line 4 column 16 (char 53)

如何解决此错误？

推荐答案

您的文件无效：没有这样的转义序列，例如 \y 在JSON中，并且必须自己转义反斜杠，因此： \\ 。

Your file is not valid: there's no such escape sequence as \y in JSON, and bare backslashes must themselves be escaped thus: \\.

如果可以的话，最简单的解决方案是修复

The simplest solution, if you can, is to fix your file so that it is valid JSON, by escaping that backslash.

如果由于某种原因您不能这样做，则可以为 json.loads（）捕获此特定错误并修补源文本：

If for some reason you can't, it's possible to write a wrapper for json.loads() that catches this specific error and patches up the source text:

import json
from json.decoder import JSONDecodeError

def permissive_json_loads(text):
    while True:
        try:
            data = json.loads(text)
        except JSONDecodeError as exc:
            if exc.msg == 'Invalid \\escape':
                text = text[:exc.pos] + '\\' + text[exc.pos:]
            else:
                raise
        else:
            return data

为简单起见，上面的函数使用字符串而不是文件。

For the sake of simplicity, the function above takes a string rather than a file.

这也是一种大锤，可以破解坚果方法，反复尝试加载整个JSON文档，并将所有未转义的反斜杠修复为它找到了它们-对于很少出现问题的小型JSON文档是合理的，但是如果您要处理带有许多这些未转义的反斜杠错误的大型JSON文档，则不合适。

It's also something of a "sledgehammer to crack a nut" approach, repeatedly trying to load the whole JSON document and fixing any unescaped backslashes as it finds them – which is reasonable for small JSON documents that rarely have the problem, but less appropriate if you're handling large JSON documents with lots of these unescaped backslash errors.

在这里起作用：

>>> print(text)
{
  "host":"1.2.3.4",
  "user":"abc",
  "passwd":"s&]\yz$&u42/",
  "dbname":"sample",
  "port":2341
}

>>> config = permissive_json_loads(text)
>>> print(config['passwd'])
s&]\yz$&u42/

以您为例，您将从文件中读取一个字符串，然后在该字符串上调用该函数：

In your case, you'd read from your file into a string, and call the function on that:

 dbconn = "C:\abc.json"
 with open(dbconn) as conn_file:
     conn_doc = conn_file.read()
 conn = permissive_json_loads(conn_doc)

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