如何用python更新json文件

I'm trying to update existing Json file, but from some reason, the requested value is not being changed but the entire set of values (with the new value) is being appended to the original file

我试图更新现有的Json文件，但是出于某种原因，请求的值没有被更改，但是整个值集(带有新值)被附加到原始文件中

jsonFile = open("replayScript.json", "r+")
data = json.load(jsonFile)


tmp = data["location"]
data["location"] = "NewPath"

jsonFile.write(json.dumps(data))

and the result is : Required:

其结果是:

{
   "location": "NewPath",
   "Id": "0",
   "resultDir": "",
   "resultFile": "",
   "mode": "replay",
   "className":  "",
   "method":  "METHOD"
}

Actual:

实际:

{
"location": "/home/karim/storm/project/storm/devqa/default.xml",
"Id": "0",
"resultDir": "",
"resultFile": "",
"mode": "replay",
"className":  "",
"method":  "METHOD"
}
{
    "resultDir": "",
    "location": "pathaaaaaaaaaaaaaaaaaaaaaaaaa",
    "method": "METHOD",
    "className": "",
    "mode": "replay",
    "Id": "0",
    "resultFile": ""
}

2 个解决方案

#1

The issue here is that you've opened a file and read its contents so the cursor is at the end of the file. By writing to the same file handle, you're essentially appending to the file.

这里的问题是，您已经打开了一个文件并读取了它的内容，因此光标位于文件的末尾。通过写入相同的文件句柄，您实际上是添加到该文件。

The easiest solution would be to close the file after you've read it in, then reopen it for writing.

最简单的解决方案是在您读过文件之后关闭它，然后重新打开它进行写入。

with open("replayScript.json", "r") as jsonFile:
    data = json.load(jsonFile)

tmp = data["location"]
data["location"] = "NewPath"

with open("replayScript.json", "w") as jsonFile:
    json.dump(data, jsonFile)

Alternatively, you can use seek() to move the cursor back to the beginning of the file then start writing, followed by a truncate() to deal with the case where the new data is smaller than the previous.

或者，您可以使用seek()将光标移回文件的开头，然后开始编写，然后使用truncatetable()处理新数据小于前一个数据的情况。

with open("replayScript.json", "r+") as jsonFile:
    data = json.load(jsonFile)

    tmp = data["location"]
    data["location"] = "NewPath"

    jsonFile.seek(0)  # rewind
    json.dump(data, jsonFile)
    jsonFile.truncate()

#2

def updateJsonFile():
    jsonFile = open("replayScript.json", "r") # Open the JSON file for reading
    data = json.load(jsonFile) # Read the JSON into the buffer
    jsonFile.close() # Close the JSON file

    ## Working with buffered content
    tmp = data["location"] 
    data["location"] = path
    data["mode"] = "replay"

    ## Save our changes to JSON file
    jsonFile = open("replayScript.json", "w+")
    jsonFile.write(json.dumps(data))
    jsonFile.close()

#1