我的 python 函数是 returning None，即使在声明 return 语句之后也是如此。我不明白我在哪里绑腿。递归是必须的

Question

# i want to read 'jsondict' json below store it in cond,field,operator,val variable using recursion(mandatory) but my function returning None, what should i do.

''' jsondict = { “条件”：“和”， “规则”：[ { "id": "价格", “字段”：“价格”， “类型”：“双”， “输入”：“数字”， “运营商”：“少”， “价值”：10.25 }, { “条件”：“或”， “规则”：[ { "id": "类别", “字段”：“类别”， “类型”：“整数”， “输入”：“select”， “运算符”：“等于”， “价值”：2 }, { "id": "类别", “字段”：“类别”， “类型”：“整数”， “输入”：“select”， “运算符”：“等于”， “价值”：1 } ] } ] }

    cond = []
    field = []
    operator = []
    val = []
    
    def rules(n):   
        for key, value in n.items():
            #print(key, value)
            if key == 'condition':
              cond.append(value)
                       
            elif key == 'rules':
                #print(key, values)
                for i in value:
                    #print(i)
                    for a, b in i.items():
                        #print(a,b)
                        if a == 'field':
                            field.append(b)
                            #print(b)
                        elif a == 'operator':
                            operator.append(b)
                        elif a == 'value':
                            val.append(b)
                        elif a == 'condition':
                            cond.append(b)
                        elif a == 'rules':
                            for j in b:
                                print(rules(j))
                                return rules(j)   # HERE CALLING FUNTION
    rules(jsondict)    
    
    print(field)      # CHECKING IF VALUES GOING IN VARIABLES
    print(operator)
    print(val)
    print(cond)

'''

Answer 1

在递归的第 2 步中，您将规则方法应用于此类字典：

{ "id": "category", "field": "category", "type": "integer",
"input": "select", "operator": "equal", "value": 2 }

它不起作用，因为没有“规则”键。

此外，return调用该函数会导致 for 循环中断。调用不带“return”关键字的方法。

尝试这样的事情：

def rules(n):
  for key, value in n.items():
    if key == 'condition':
      cond.append(value)
    elif key =='field':
      field.append(value)
    elif key == 'operator':
      operator.append(value)
    elif key == 'value':
      val.append(value)
    elif key == 'rules':
      for v in value:
        rules(v)

我的 python 函数是 returning None，即使在声明 return 语句之后也是如此。我不明白我在哪里绑腿。递归是必须的

My python function is returning None, even if after declaring return statement. I'm unable to understand where I am legging. Recursion is mandatory

python

recursion