如何在Phoenix选择字段中显示模型的所有记录 [英] How to show all records of a model in Phoenix select field

问题描述

我有以下型号...

1. Page
2. Category

1. Page
2. Category

我在page_controller.ex

def new(conn, _params) do
  changeset = Page.changeset(%Page{})
  categories = Repo.all(Category)
  render(conn, "new.html", changeset: changeset, categories: categories)
end

在page/new.html.eex中，我有以下用于选择字段的代码

I have following code for select field in page/new.html.eex

<div class="form-group">
  <%= label f, :category_id, "Parent", class: "control-label" %>
  <%= select f, :category_id, @categories ,class: "form-control" %>
</div>

它应该在选择字段中显示所有类别，因此我可以为页面选择一个类别，但是不幸的是我找不到问题.如果您有任何建议，请告诉我.

It should show all categories in select field so i can choose one category for the page but unfortunately i am unable to find the problem. if you have any suggestion please let me know.

推荐答案

select/4 函数需要第三个参数的元组列表.

The select/4 function expects a list of tuples for the 3rd argument.

从文档中

值应该是包含两个项目元组(例如映射和关键字列表)的Enumerable，或者是将元素用作生成的select的键和值的任何Enumerable.

Values are expected to be an Enumerable containing two-item tuples (like maps and keyword lists) or any Enumerable where the element will be used both as key and value for the generated select.

尝试将您的控制器更改为:

Try changing your controller to:

categories = Repo.all(Category) |> Enum.map(&{&1.name, &1.id})

这也可以在查询级别完成:

This can also be done at the query level:

query = from(c in Category, select: {c.name, c.id})
categories = Repo.all(query)

请参见凤凰城:订购查询集，以获取有关将查询定义为模型中的功能.

See Phoenix: Ordering a query set for an explanation of defining a query as a function in your model.

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