Django Admin Inline默认生成多字段问题及解决方法

问题描述 #

我有一个关联Ticket模型外键的TicketMessage模型，希望在Ticket的Admin面板中以Inline形式展示TicketMessage的message字段。实现后发现默认生成了三个message字段而非预期的一个，需要了解该问题产生的原因，以及如何设置为默认仅显示一个message字段。

TicketMessage模型代码 #

from django.db import models
from django.utils.translation import gettext as _

from painless.models import TimeStampMixin

class TicketMessage(TimeStampMixin):

    class Meta:
        verbose_name = _("Ticket Message"),
        verbose_name_plural = ("Ticket Messages")

  
    ticket = models.ForeignKey(
        "Ticket",
        default=False,
        on_delete=models.PROTECT,
        related_name="ticket_message",
        help_text="Lorem ipsum"
    )

    message = models.TextField(
        _("message"),
        max_length=500,
        help_text="Lorem ipsum",
    )


    def __str__(self):
        return f"Ticket subject: {self.ticket}"

    def __repr__(self):
        return f"Ticket subject: {self.ticket}"

Ticket Admin配置代码 #

from django.contrib import admin
from django.utils.translation import gettext_lazy as _

from desk.models import (
    Ticket,
    TicketMessage
)


class TicketMessageInline(admin.TabularInline):
    model = TicketMessage


@admin.register(Ticket)
class TicketAdmin(admin.ModelAdmin):

    list_display = (
        'subject',
        'status_choices',
        'priority_choices',
        'is_read',
        'is_important',
        'is_archive',
    )

    list_filter = (
        'is_read',
        'is_important',
        'is_archive',
        'status_choices',
    )

    inlines = (
        TicketMessageInline,
    )

    filter_horizontal = (
        "tags",
    )

    
    fieldsets = (
        (_("Primary Informations"), {
            'fields': (
                'subject',
                'message',
                'status_choices',
                'priority_choices',
            )
        }),

        (_("Options"), {
            'fields': (
                'is_important',
                'is_archive',
                'is_read',
                'is_duplicated',
            )
        }),

        
        (_("Others"), {
            'fields': (
                'department',
                'resolved_at',
            )
        }),

        
        (_("Tags"), {
            'fields': (
                'tags',
            )
        }),
    )

问题原因 #

Django Admin的Inline类默认设置extra = 3，这个属性用于控制表单中额外显示的空白输入表单数量，因此默认会渲染3个空白的message输入字段。

解决方案 #

在TicketMessageInline类中添加extra = 1参数，即可将默认显示的空白message字段数量改为1个。修改后的完整Admin配置代码如下：

from django.contrib import admin
from django.utils.translation import gettext_lazy as _

from desk.models import (
    Ticket,
    TicketMessage
)


class TicketMessageInline(admin.TabularInline):
    model = TicketMessage
    extra = 1


@admin.register(Ticket)
class TicketAdmin(admin.ModelAdmin):

    list_display = (
        'subject',
        'status_choices',
        'priority_choices',
        'is_read',
        'is_important',
        'is_archive',
    )

    list_filter = (
        'is_read',
        'is_important',
        'is_archive',
        'status_choices',
    )

    inlines = (
        TicketMessageInline,
    )

    filter_horizontal = (
        "tags",
    )


    fieldsets = (
        (_("Primary Informations"), {
            'fields': (
                'subject',
                'message',
                'status_choices',
                'priority_choices',
            )
        }),

        (_("Options"), {
            'fields': (
                'is_important',
                'is_archive',
                'is_read',
                'is_duplicated',
            )
        }),


        (_("Others"), {
            'fields': (
                'department',
                'resolved_at',
            )
        }),


        (_("Tags"), {
            'fields': (
                'tags',
            )
        }),
    )

内容的提问来源于stack exchange，提问作者Thoughtless Thinker