Question

我有一个Django应用程序，允许用户创建变量并命名它们

class Product(models.Model):
    name = models.CharField(max_length=40, unique=True)
    int1_name = models.CharField(max_length=60, blank=True, null=True)
    int1_default = models.IntegerField(blank=True, null=True)
    int2_name = models.CharField(max_length=60, blank=True, null=True)
    int2_default = models.IntegerField(blank=True, null=True)
    float1_name = models.CharField(max_length=60, blank=True, null=True)
    float1_default = models.FloatField(blank=True, null=True)
    float2_name = models.CharField(max_length=60, blank=True, null=True)
    float2_default = models.FloatField(blank=True, null=True)
    string1_name = models.CharField(max_length=60, blank=True, null=True)
    string1_default = models.CharField(max_length=60, blank=True, null=True)
    string2_name = models.CharField(max_length=60, blank=True, null=True)
    string2_default = models.CharField(max_length=60, blank=True, null=True)

然后存储它们

class ItemData(models.Model):
    created = models.DateTimeField(default=datetime.now)
    item = models.ForeignKey(Item, editable=False)
    int1_val = models.IntegerField(blank=True, null=True)
    int2_val = models.IntegerField(blank=True, null=True)
    float1_val = models.DecimalField(blank=True, null=True, max_digits=12, decimal_places=2)
    float2_val = models.DecimalField(blank=True, null=True, max_digits=12, decimal_places=2)
    string1_val = models.CharField(max_length=60, blank=True, null=True)
    string2_val = models.CharField(max_length=60, blank=True, null=True)

当我向用户提供一个表单（他们已经创建）填写时，我会执行以下操作，使用用户为变量指定的名称来填充字段

class ItemDataForm(ModelForm):

    # Only renames the fields based on whether the product has a name for the field
    def __init__(self,product,*args,**kwargs):
        super(ItemDataForm, self).__init__(*args, **kwargs)
        # delete all the fields that will be automatically filled in when saving
        del self.fields['created']
        # if the values is set in the product
        if product.int1_name:
            self.fields['int1_val'].label = product.int1_name
            self.fields['int1_val'].value = product.int1_default
        else:
            del self.fields['int1_val']
        if product.int2_name:
            self.fields['int2_val'].label = product.int2_name
            self.fields['int2_val'].value = product.int2_default
        else:
            del self.fields['int2_val']
        if product.float1_name:
            self.fields['float1_val'].label = product.float1_name
            self.fields['float1_val'].value = product.float1_default
        else:
            del self.fields['float1_val']
        if product.float2_name:
            self.fields['float2_val'].label = product.float2_name
            self.fields['float2_val'].value = product.float2_default
        else:
            del self.fields['float2_val']
        if product.string1_name:
            self.fields['string1_val'].label = product.string1_name
            self.fields['string1_val'].value = product.string1_default
        else:
            del self.fields['string1_val']
        if product.string2_name:
            self.fields['string2_val'].label = product.string2_name
            self.fields['string2_val'].value = product.string2_default
        else:
            del self.fields['string2_val']

有没有什么方法可以做到这一点pythonicaly像列表是settings.py并循环它：

USER_SETTABLE_VARIABLES = ['int1','int2','float1','float2','string1','string2']

这同样适用于我在保存之前确保输入的数据是唯一的方式：

def is_unique(self,latestSI):
    if (self.cleaned_data['int1_val'] == latestSI.int1_val and
        self.cleaned_data['int2_val'] == latestSI.int2_val and
        self.cleaned_data['float1_val'] == latestSI.float1_val and
        self.cleaned_data['float2_val'] == latestSI.float2_val and
        self.cleaned_data['string1_val'] == latestSI.string1_val and
        self.cleaned_data['string2_val'] == latestSI.string2_val):
        return False
    else:
        return True

我只是问，因为当我想添加到模型时，我不想编辑所有这些功能。

Answer 1

请勿使用exec！ getattr完全足够，更安全，也更易读。

class ItemDataForm(ModelForm):
    def __init__(self,product,*args,**kwargs):
        super(ItemDataForm, self).__init__(*args, **kwargs)
        del self.fields['created']
        fields = 'int1', 'int2', 'float1', 'float2', 'string1', 'string2'
        for field in fields:
            val = getattr(product, field + '_name')
            fval = field + '_val'
            if val:
                self.fields[fval].label = val
                self.fields[fval].value = getattr(product, field + '_default')
            else:
                del self.fields[fval]

Answer 2

可能有更好的方法，但无需添加任何大量代码，您可以尝试这样做：

USER_SETTABLE_VARIABLES = ['int1','int2','float1','float2','string1','string2']

for variable in USER_SETTABLE_VARIABLES:
  exec("if if product."+variable+":\n\tself.fields['" + variable + "'].label = product."+variable+"\n\tself.fields['"+variable+"'].value = product."+variable+"\nelse:\n\tdel self.fields['"+variable+"']

但这只会省去编写一些代码的麻烦，并且可以更容易地添加更多用户可设置的变量。但我不推荐这种方法，因为你的代码会变得不那么可读

使用getattr实现相同的功能：

for variable in USER_SETTABLE_VARIABLES:
   if getattr(product, variable):
       self.fields[variable].label = getattr(product, variable):
       .....
   else:
       .....

更多Pythonic方式为多个属性重复某些操作

2 个答案: