django表单下拉字段中的占位符 [英] Placeholder in django form dropdown field

问题描述

我对Django形式的下拉字段有一点疑问。我想在此字段中添加占位符（或不使用活动的第一选项作为占位符），并添加一些其他内容，例如不添加标签，类等。
我在 forms.py ，但现在我的表单已损坏-不要将值保存到数据库。

I have a little problem with a dropdown field in django form. I want to add to this field placeholder (or not active first option as placeholder) and some other stuff as no label, class etc. I wrote something like this, in my forms.py but now my form is broken - don't save values to database.

from .models import Scenario, ScenarioArea
from django import forms

class newScenario(forms.ModelForm):
    scenarioArea=forms.ModelChoiceField(label="", queryset=ScenarioArea.objects.values_list("scenarioAreaName", flat=True).distinct(), empty_label=None)

lass Meta:
        model = Scenario
        fields = ['scenarioArea']

其他所有字段类型都可以使用，但是此下拉列表不起作用...
您能帮我吗？

Every other field type is working, but not this dropdown... Could you help me?

推荐答案

默认情况下，ModelChoiceField使用的窗口小部件的顶部会有
空选择清单。您可以使用empty_label
属性更改此
标签的文本（默认情况下为 ---------），也可以通过设置$ b完全禁用空标签$ b empty_label设置为None：

By default the widget used by ModelChoiceField will have an empty choice at the top of the list. You can change the text of this label (which is "---------" by default) with the empty_label attribute, or you can disable the empty label entirely by setting empty_label to None:

将 empty_label 设置为无，此选项未显示。

As you're setting empty_label to None, this option is not being shown.

示例

scenario_area = forms.ModelChoiceField(label="", queryset=ScenarioArea.objects.distinct('scenarioAreaName'), empty_label="Placeholder")

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