Phoenix:订购查询集 [英] Phoenix: Ordering a query set

问题描述

我(一个菜鸟)在玩Phoenix框架，玩得开心，并建立了一个很小的twitter克隆.我一切正常，但是，我想按updated_at字段(升序)排序推文.从tweet_controller可以看到，我试图弄乱order_by子句，但这对我没有任何帮助.

I'm [a noob] playing around with the Phoenix framework for fun and building a small twitter clone. I everything working, however, I want to order the tweets by the updated_at field (ascending). As you can see from tweet_controller, I have tried messing around with an order_by clause, but this did nothing for me.

问题

我该如何实现?在EEx内还是在tweet_controller本身内?

How do I achieve this? Within the EEx or within the tweet_controller itself?

tweet/index.html.eex

<div class="row">
  <%= for tweet <- @tweets do %>

  <h4><%= tweet.tweet %></h4>

  <% end %> 
</div>

controllers/tweet_controller.ex

...
alias TodoApp.Tweet

def index(conn, _params) do
  tweets = Repo.all(Tweet, order_by: tweet)
  render(conn, "index.html", tweets: tweets)
end
...

推荐答案

您需要使用 Ecto查询:

query = from(t in Tweet, order_by: t.updated_at)
tweets = Repo.all(query)

您可能要考虑在Tweet模型中为查询定义一个函数.

You may want to consider defining a function in your Tweet model for the query.

def ordered(query) do
  from t in query,
    order_by: t.updated_at
end

您还可以使用函数语法:

You can also use the function syntax:

def ordered(query) do
  query
  |> order_by([t], t.updated_at)
end

然后您可以在控制器中使用它:

Then you can use this in your controller:

tweets = Tweet |> Tweet.ordered() |> Repo.all()

以下是有关查询的好帖子: http://blog.drewolson.org/composable -queries-ecto/

Here is a good post on queries: http://blog.drewolson.org/composable-queries-ecto/

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