我可以获得正确的数据以在我的 ERB 中显示，但我没有遵循标准。你能帮忙吗？

发布于 2024-10-16 01:10:59 字数 958 浏览 1 评论 0原文

我有两个模型：用户和交易。 Transactions 表有 user_id 列，用于存储负责事务的用户的 id。

在交易的index.html.erb上，这是自动生成的代码：

<td><%=h transaction.user_id %></td>

由于我希望显示用户名，因此在我的第一种方法中，我将其转换为：

# Index.html.erb
# First approach
<td><%=h User.find(:first, :conditions => ["id =?", transaction.user_id]).firstname %></td>

这让我正确地得到了名字，但我不确定这是正确的这样我在 user.rb （模型文件）中创建了这个方法：

# user.rb
# Second approach
def find_by_id id
    @firstname = User.find(:first, :conditions => ["id =?", id]).firstname
    return @firstname
end

并将 index.html.erb 中的行修改为：

# Index.html.erb
# Second approach
<td><%=h User.find_by_id(transaction.user_id) %></td>

但这并没有给我用户的名字，而是输出类似于 #< ;User:0x000000021ecf60>

我不确定：a) 为什么会发生这种情况以及如何从方法中获取返回值以正确打印& b）如果我即使在第二种打印用户名的方法中也遵循标准。

原文

I have two models: user and transaction. Transactions table has user_id column for storing the id of the user responsible for transaction.

On the index.html.erb for transactions this was the auto generated code:

<td><%=h transaction.user_id %></td>

Since I want user's name to be displayed, in my first approach I converted this to:

# Index.html.erb
# First approach
<td><%=h User.find(:first, :conditions => ["id =?", transaction.user_id]).firstname %></td>

This got me the firstname correctly, but I was not sure this was the right way so I created this method in user.rb (model file):

# user.rb
# Second approach
def find_by_id id
    @firstname = User.find(:first, :conditions => ["id =?", id]).firstname
    return @firstname
end

And modified the line in index.html.erb to:

# Index.html.erb
# Second approach
<td><%=h User.find_by_id(transaction.user_id) %></td>

But this does not give me user's firstname and instead the output is something like #<User:0x000000021ecf60>

I am not sure: a) Why this is happening and how to get the return from method to print correctly & b) If I am following standards even in second approach to getting the username printed.

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━╋う一瞬間旳綻放 2024-10-23 01:10:59

假设您在事务模型中正确设置了事务和用户之间的关联：

class Transaction < ActiveRecord::Base
  belongs_to :user
end

那么您可以简单地执行以下操作：

<td><%=h transaction.user.firstname %></td>

您的“find_by_id”方法不起作用的原因是因为您将其创建为实例方法。因此，当您调用 User.find_by_id 时，它使用普通的 Rails“魔术方法”（一点也不神奇 - 它只是使用 method_missing）来查找记录。我认为，当您拥有所有这些面向对象的可爱功能时，重写此方法以仅返回用户的名字是非常糟糕的设计。

Assuming you have your association between transactions and users setup properly in the transaction model:

class Transaction < ActiveRecord::Base
  belongs_to :user
end

Then you can simply do:

<td><%=h transaction.user.firstname %></td>

The reason your 'find_by_id' method didn't work is because you created it as an instance method. So, when you called User.find_by_id, it used the normal Rails 'magic method' (not so magic at all - it just uses method_missing) for finding records. I would argue that it is very bad design to override this method to just return the first name of the user when you've got all this object-oriented loveliness around.

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