Python 变量已声明但仍然报错

Question

我想将请求中的数据分配给代码中多处使用的变量 currentKampjson。但是当我尝试将 currentKampjson 分配给任何它被声明为新变量的东西时，这适用于每个变量。

currentKampjson是字典类型变量

currentKampjson = {"info":1, "info2":3}

@app.route("/stream/currentkamp")
def streamCurrentKamp():
    return render_template("stream/currentKamp.html", kamp = currentKampjson)

@app.route("/currentKamp/getKamp")
def getCurrentKamp():
    return jsonify(currentKamp)
    
print(currentKampjson)
@app.route("/currentKamp/update", methods=["POST"])
def updateCurrentKamp():
    indata = eval(request.data)
    
    currentKampjson = indata
    with open("jsonFiles/kamper/currentKamp.json","w") as f:
        json.dump(indata, f)
    return "SUCCESS"

此代码运行良好，即使我在这里使用 currentKampjson：

@app.route("/currentKamp/update", methods=["POST"])
def updateCurrentKamp():
    indata = eval(request.data)
    print(currentKampjson)
    #currentKampjson = indata
    with open("jsonFiles/kamper/currentKamp.json","w") as f:
        json.dump(indata, f)
    return "SUCCESS"

Answer 1

在当前情况下，您需要对变量使用 global 关键字，但在通常情况下，全局变量不是一个好的做法。

您可以阅读有关范围的更多信息，例如这里：

https://realpython.com/python-scope-legb-rule/ https://matthew-brett.github.io/teaching/global_scope.html

currentKampjson = {"info":1, "info2":3}

@app.route("/stream/currentkamp")
def streamCurrentKamp():
    global currentKampjson
    return render_template("stream/currentKamp.html", kamp=currentKampjson)

@app.route("/currentKamp/getKamp")
def getCurrentKamp():
    return jsonify(currentKamp)
    
print(currentKampjson)

@app.route("/currentKamp/update", methods=["POST"])
def updateCurrentKamp():
    global currentKampjson
    indata = eval(request.data)
    
    currentKampjson = indata

    with open("jsonFiles/kamper/currentKamp.json", "w") as f:
        json.dump(indata, f)

    return "SUCCESS"

Python 变量已声明但仍然报错

Python variable is declared and still gives error

python

variables

scope

flask