如何创建按父分组的子模型记录的下拉列表 [英] How to create dropdown list of child model records grouped by the parent

问题描述

我有三个模型：属性，城市和区域。一个城市属于一个地区，而一个地区则有许多城市。用户在定义新属性时选择一个城市。

I have three models, Properties, Cities and Regions. A city belongs_to a region and region has_many cities. The user picks a city when defining a new property.

有很多城市，因此我希望下拉列表如下所示：

There are many cities so I'd like to have the dropdown list look something like this:

Region 1:
 City 1
 City 2
 City 3
Region 2:
 City 4
 City 5

等。但是只有城市是可以选择的，即区域是灰色的，并且仅作为视觉引导。有没有一种方法可以按父分组子记录？

etc. But only the cities are selectable, ie the regions are greyed out and are only there as a visual guide. Is there a way to group the child records by parent?

推荐答案

您要使用rails option_groups_from_collection_for_select帮助器

You want to use the rails "option_groups_from_collection_for_select" helper

http ：//api.rubyonrails.org/classes/ActionView/Helpers/FormOptionsHelper.html#method-i-option_groups_from_collection_for_select

= option_groups_from_collection_for_select(@regions, :cities, :name, :id, :name, 3)

如果您要手动提供2级选项数组，则使用 grouped_options_for_select

if you want to manually provide the 2 level array of options, then use "grouped_options_for_select"

http://api.rubyonrails.org/classes/ActionView/Helpers/FormOptionsHelper.html#method-i-grouped_options_for_select

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