轨道 - 找到条件在轨道4 [英] rails - find with condition in rails 4

问题描述

我最近将rails升级到了Rails 4.1.6。
$ b 这个查询用于工作：

  @user = User.find（：all：：conditions => {：name =>'batman'}）
  

现在我得到这个错误信息：

$ $ $ $ $ $ $ $ $ $找不到全部使用'id'的用户：（all，{：conditions => {：name =>batman}}）（找到0结果，但是正在寻找2）
/ pre>

当我检查日志时，我可以看到rails正在尝试做一个完全不同的查询：

<$用户负载（0.4ms）SELECTusers。* FROMusersWHEREusers。idIN（'all'，'---
：conditions ：
：name：batman
'）

让所有的用户ID为全部和{：conditions => {：name =>蝙蝠侠}}。请帮助。

UPDATE：

我真正的问题是我想获得一个特定的用户并添加给他的车，只有蓝色的车。例如，这是我的查询，用户ID是20。
$ b $ $ p $ @user = User.joins（：cars）.find（ 20，：cars => {：color =>blue}）


这个错误：
$ b

找不到所有用户都是'id'：（20，{：cars => {：color =>蓝色}}）
（找到41个结果，但是正在寻找2）

解决方案

其他一些人已经指出：查询语法改变了。试试这个：

$ p $ @user = User.joins（：cars）.where（：cars => {：color => ;blue}）。find（20）


注意，如果该记录会引发异常没有找到，返回一个空数组而不是调用：

  @user = User.joins（：cars）.where（： id => 20，：cars => {：color =>blue}）
  

我建议阅读： http://guides.rubyonrails.org/active_record_querying.html

---

如果你想加载用户，即使他没有任何汽车，也不能显示他的蓝色汽车，它是这样的：

$ p $ @user = User.find（20）＃返回用户
@ user.cars。其中（：color =>'blue'）＃返回用户的蓝色汽车（或一个空的数组）


I recently upgraded my rails to Rails 4.1.6.

This query used to work :

@user = User.find(:all, :conditions => { :name => 'batman' })

Now I get this error message:

Couldn't find all Users with 'id': (all, {:conditions=>{:name=>"batman"}}) (found 0 results, but was looking for 2)

When I check the logs I can see that rails is trying to do a completely different query :

User Load (0.4ms)  SELECT "users".* FROM "users"  WHERE "users"."id" IN ('all', '---
:conditions:
  :name: batman
')

It looks like, it's trying to get all the users with the id "all" and "{:conditions=>{:name=>"batman"}}". Please help.

UPDATE:

My real question behind that was I want to get a specific user and add to it his cars, only the cars that are blue. For example this is my query, the user id is 20.

@user = User.joins(:cars).find(20, :cars => {:color => "blue"})

But I get this error:

Couldn't find all Users with 'id': (20, {:cars=>{:color=>"blue"}}) (found 41 results, but was looking for 2)

解决方案

Some others already pointed out: The query syntax changed. Try this:

@user = User.joins(:cars).where(:cars => { :color => "blue" }).find(20)

Note that this will raise an exception if that record is not found, to return an array empty instead call:

@user = User.joins(:cars).where(:id => 20, :cars => { :color => "blue" })

I suggest to read: http://guides.rubyonrails.org/active_record_querying.html

---

If you want to load the user even if he does not have any cars and than display only his blue cars, I would do it like this:

@user = User.find(20)              # returns the user
@user.cars.where(:color => 'blue') # returns the user's blue cars (or an empty array)

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