Django自定义表单中外键显示pk而非name字段的问题求助

在编辑Django模型时，表单的外键字段（service和device）在ChoiceTxtField输入框中显示的是模型的PK编号，而非对应的name字段值，需要调整让其显示name字段。

现有代码 #

forms.py #

class ListTextWidget(forms.Select):
    template_name = 'include/_forms_orders_datalist.html'

    def format_value(self, value):
        if value == '' or value is None:
            return ''
        if self.is_localized:
            return formats.localize_input(value)
        return str(value)

class ChoiceTxtField(forms.ModelChoiceField):
    widget=ListTextWidget()

class SimpleOrderEditForm(forms.ModelForm):
    service = ChoiceTxtField(queryset=Service.objects.order_by('-used'))
    device = ChoiceTxtField(queryset=Device.objects.order_by('-used'))

    def __init__(self, *args, **kwargs):
        self.request = kwargs.pop('request', None)
        super(SimpleOrderEditForm, self).__init__(*args, **kwargs)
        status_excluded = ['','-']
        self.fields['service'].choices = [(k, v) for k, v in self.fields['service'].choices if k not in status_excluded]
        self.fields['device'].choices = [(k, v) for k, v in self.fields['device'].choices if k not in status_excluded]

    class Meta:
        model = Orders
        fields = ['device','service']
        widgets = {}

include/_forms_orders_datalist.html #

<input id="ajax_input_{{ widget.name }}" list="{{ widget.name }}" autocomplete="off"
    {% if widget.value != None %} name="{{ widget.name }}" value="{{ widget.value|stringformat:'s' }}"{% endif %}
    {% include "django/forms/widgets/attrs.html" %}>

    {% for group_name, group_choices, group_index in widget.optgroups %}
        {% for option in group_choices %}
            <span class="badge rounded-pill bg-warning text-dark" id="list-item-{{ widget.name }}" name="list-item-{{ widget.name }}">
                {% include option.template_name with widget=option %}</span>
        {% endfor %}
            {% endfor %}

<datalist id="{{ widget.name }}">
    <optgroup label="">
    </optgroup>
</datalist>

models.py #

class Orders(models.Model):
    service = models.ForeignKey('Service', default=1, on_delete = models.SET_DEFAULT, null=True, verbose_name='Услуга', related_name='get_service')
    device = models.ForeignKey('Device', default=1,  on_delete = models.SET_DEFAULT, null=True, verbose_name='Устройство', related_name='get_device')

class Service(models.Model):
    name = models.CharField(max_length=150, db_index=True, unique=True, verbose_name='Наименования услуги')

    def __str__(self):
        return self.name


class Device(models.Model):
    name = models.CharField(max_length=150, db_index=True, unique=True, verbose_name='Устройство')

解决方案 #

1. 给Device模型添加__str__方法 #

Service模型已经定义了__str__返回name，但Device模型缺少该方法，导致choices中的显示值异常。添加后，表单choices的文本会自动使用模型的name字段：

class Device(models.Model):
    name = models.CharField(max_length=150, db_index=True, unique=True, verbose_name='Устройство')
    
    def __str__(self):
        return self.name

2. 修改ListTextWidget的format_value方法 #

当前format_value直接返回PK的字符串形式，需要修改为根据PK获取对应模型实例的name值：

from django.core.exceptions import ObjectDoesNotExist

class ListTextWidget(forms.Select):
    template_name = 'include/_forms_orders_datalist.html'

    def format_value(self, value):
        if value == '' or value is None:
            return ''
        if self.is_localized:
            return formats.localize_input(value)
        # 根据PK获取模型实例，返回name字段
        try:
            # 从widget关联的queryset中查询实例
            instance = self.choices.queryset.get(pk=value)
            return instance.name
        except (ObjectDoesNotExist, AttributeError):
            # 异常情况下返回原PK值，避免报错
            return str(value)

3. （可选）模板层调整显示逻辑 #

如果不想修改widget，也可以在模板中通过遍历choices找到当前选中项的文本：

{% with selected_text=widget.value|stringformat:'s' %}
    {% for group_name, group_choices, group_index in widget.optgroups %}
        {% for option in group_choices %}
            {% if option.value == widget.value|stringformat:'s' %}
                {% with selected_text=option.label %}
                {% endwith %}
            {% endif %}
        {% endfor %}
    {% endfor %}

    <input id="ajax_input_{{ widget.name }}" list="{{ widget.name }}" autocomplete="off"
        {% if widget.value != None %} name="{{ widget.name }}" value="{{ selected_text }}"{% endif %}
        {% include "django/forms/widgets/attrs.html" %}>
{% endwith %}

说明 #

完成上述修改后，表单输入框会显示外键关联模型的name字段值，而非PK编号。其中第一步是基础（保证choices的文本正确），第二步是核心（让input的value显示name），按需选择修改方式即可。

内容的提问来源于stack exchange，提问作者JopaBoga