如何从Django中的ModelForm手动创建一个选择字段？ [英] How to manually create a select field from a ModelForm in Django?

问题描述

我有一个 ModelForm 其中一个字段（名为创建者）是一个 ForeignKey ，所以对于 {{form.creator}} Django呈现< select> 标签如下：

I have a ModelForm where one of the field (named creator) is a ForeignKey, so for {{ form.creator }} Django renders the <select> tag like this:

<select id="id_approver" name="approver">
    <option selected="selected" value="">---------</option>
    <option value="1">hobbes3</option>
    <option value="2">tareqmd</option>
    <option value="3">bob</option>
    <option value="4">sam</option>
    <option value="5">jane</option>
</select>

但是我想添加一个 onchange 事件属性，所以我以后可以使用AJAX做别的事情。我也想更改 --------- 来表示其他内容，并显示审批者的全名，而不是其用户名。

But I want to add a onchange event attribute so I can use AJAX later to do something else. I also want to change --------- to say something else and display the approvers' full name, not their username.

那么可以得到可能的批准者列表并生成我自己的选择选项？类似

So is it possible to get a list of possible approvers and generate my own select options? Kind of like

<select id="id_approver" name="approver" onchange="some_ajax_function()">
    <option select="selected" value="0">Choose a user</option>
{% for approver in form.approver.all %} <!-- This won't work -->
    <option value="{{ approver.pk }}">{{ approver.get_full_name }}</option>
{% endfor %}
</select>

而且，我也认为大多数审批者名单太大（比如50多个）那么我最终会想要一个可以查询的自动完成字段给审批者。所以我一定要写自己的HTML。

And I'm also thinking most of the list of approvers get too large (like over 50), then I'll eventually want some sort of a searchable auto-complete field for the approver. So then I'll definitely need to write my own HTML.

如果有人需要它，我的 ModelForm 像这样：

In case anyone needs it, my ModelForm looks like this:

class OrderCreateForm( ModelForm ) :
    class Meta :
        model = Order
        fields = (
            'creator',
            'approver',
            'work_type',
            'comment',
        )

推荐答案

ModelChoiceField文档解释了如何做到这一点。

The ModelChoiceField documentation explains how to do this.

要更改空的标签： p>

To change the empty label:

empty_label

    By default the <select> 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:

    # A custom empty label
    field1 = forms.ModelChoiceField(queryset=..., empty_label="(Nothing)")

    # No empty label
    field2 = forms.ModelChoiceField(queryset=..., empty_label=None)

对于你的第二个查询，它也在文档中解释：

As for your second query, it is also explained the in docs:

The __unicode__ method of the model will be called to generate string
representations of the objects for use in the field's choices;
to provide customized representations, subclass ModelChoiceField and override
label_from_instance. This method will receive a model object, and should return
a string suitable for representing it. For example:

class MyModelChoiceField(ModelChoiceField):
    def label_from_instance(self, obj):
        return "My Object #%i" % obj.id

最后，要传递一些自定义ajax，请使用 attrs 参数为选择小部件（这是在ModelForm字段中使用什么）。

Finally, to pass some custom ajax, use the attrs argument for the select widget (which is what is used in the ModelForm field).

最后你应该有这样的东西：

In the end, you should have something like this:

creator = MyCustomField(queryset=...,
                        empty_label="Please select",
                        widget=forms.Select(attrs={'onchange':'some_ajax_function()'})

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