Python 读取 JSON 字符串 | 类型错误：字符串索引必须是整数
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Reading a JSON string | TypeError: string indices must be integers
提问by Billy Dawson
I'm trying to create a program that will read in a JSON string through the GUI and then use this to perform additional functions, in this case breaking down a mathematical equation. At the moment I am getting the error:
我正在尝试创建一个程序，该程序将通过 GUI 读取 JSON 字符串，然后使用它来执行其他功能，在这种情况下分解数学方程式。目前我收到错误：
"TypeError: string indices must be integers"
“类型错误：字符串索引必须是整数”
and I have no idea why.
我不知道为什么。
The JSON I am trying to read in is as follows:
我试图读入的 JSON 如下：
{
"rightArgument":{
"cell":"C18",
"value":9.5,
"type":"cell"
},
"leftArgument":{
"rightArgument":{
"cell":"C3",
"value":135,
"type":"cell"
},
"leftArgument":{
"rightArgument":{
"cell":"C4",
"value":125,
"type":"cell"
},
"leftArgument":{
"cell":"C5",
"value":106,
"type":"cell"
},
"type":"operation",
"operator":"*"
},
"type":"operation",
"operator":"+"
},
"type":"operation",
"operator":"+"
}
import json
import tkinter
from tkinter import *
data = ""
list = []
def readText():
mtext=""
mtext = strJson.get()
mlabel2 = Label(myGui,text=mtext).place(x=180,y=200)
data = mtext
def mhello():
_getCurrentOperator(data)
def _getCurrentOperator(data):
if data["type"] == "operation":
_getCurrentOperator(data["rightArgument"])
_getCurrentOperator(data["leftArgument"])
list.append(data["operator"])
elif data["type"] == "group":
_getCurrentOperator(data["argument"])
elif data["type"] == "function":
list.append(data["name"]) # TODO do something with arguments
for i in range(len(data["arguments"])):
_getCurrentOperator(data["arguments"][i])
else:
if (data["value"]) == '':
list.append(data["cell"])
else:
list.append(data["value"])
print(list)
myGui = Tk()
strJson = StringVar()
myGui.title("Simple Gui")
myGui.geometry("400x300")
label = Label(text = 'Welcome!').place(x=170,y=40)
btnStart = Button(myGui,text='Start',command=mhello).place(x=210,y=260)
btnRead = Button(myGui,text='Read text',command=readText).place(x=210,y=200)
txtEntry = Entry(myGui, textvariable=strJson).place(x=150,y=160)
btnOptions = Button(myGui, text = "Options").place(x=150,y=260)
myGui.mainloop()
采纳答案by Vincent Beltman
You are never parsing the string to a dictionary (json object). Change data = mtextto: data = json.loads(mtext)You should also add global datato the readText method
您永远不会将字符串解析为字典（json 对象）。更改data = mtext为：data = json.loads(mtext)您还应该添加global data到 readText 方法
回答by mhawke
TypeError: string indices must be integersmeans an attempt to access a location within a string using an index that is not an integer. In this case your code (line 18) is using the string "type"as an index. As this is not an integer, a TypeErrorexception is raised.
TypeError: string indices must be integers表示尝试使用非整数索引访问字符串中的位置。在这种情况下，您的代码（第 18 行）使用字符串"type"作为索引。由于这不是整数，因此TypeError会引发异常。
It seems that your code is expecting datato be a dictionary. There are (at least) 3 problems:
您的代码似乎希望data成为字典。有（至少）3个问题：
- You are not decoding ("loading") the JSON string. For this you should use
json.loads(data)in thereadText()function. This will return the dictionary that your code expects elsewhere. datais a global variable with value initialised to an empty string (""). You can not modify a global variable within a function without first declaring the variable using theglobalkeyword.- The code builds a list by appending successive items to it, however, that list is not used elsewhere. It is printed after the definition of
_getCurrentOperator()but this is before any processing has been done, hence it is still empty at that point and[]is displayed. Moveprint(list)tomhello()after_getCurrentOperator(). (BTW usinglistas a variable name is not advised as this shadows the builtinlist)
- 您没有解码（“加载”）JSON 字符串。为此，您应该
json.loads(data)在readText()函数中使用。这将返回您的代码在其他地方期望的字典。 data是一个全局变量，其值初始化为空字符串 ("")。您不能在没有首先使用global关键字声明变量的情况下修改函数内的全局变量。- 代码通过向列表追加连续项来构建列表，但是，该列表不会在其他地方使用。它在定义之后打印，
_getCurrentOperator()但这是在任何处理完成之前，因此在该点它仍然是空的[]并被显示。移动print(list)到mhello()后_getCurrentOperator()。（顺便说一句list，不建议使用作为变量名，因为这会影响内置list）
You can revise readText()to this:
您可以修改readText()为：
def readText():
global data
mtext=""
mtext = strJson.get()
mlabel2 = Label(myGui,text=mtext).place(x=180,y=200)
data = json.loads(mtext)
回答by Brian Sanchez
sometimes you need to use json.loads again.. this worked for me..
有时你需要再次使用 json.loads .. 这对我有用..
jsonn_forSaleSummary_string = json.loads(forSaleSummary) //still string
jsonn_forSaleSummary = json.loads(jsonn_forSaleSummary_string)
finally!! json
最后！！json
