ActiveRecord的寻找，只返回选定列 [英] ActiveRecord find and only return selected columns
问题描述
如果你穿过这个绊倒，检查这两个答案，因为我现在会用勇气此
If you stumble across this, check both answers as I'd now use pluck for this
我有一个相当大的自定义数据集，我想回到被echoe'd出来为JSON。一个部分是：
I have a fairly large custom dataset that I'd like to return to be echoe'd out as json. One part is:
l=Location.find(row.id)
tmp[row.id]=l
但我想要做的是这样的：
but I'd like to do something like:
l=Location.find(row.id).select("name, website, city")
tmp[row.id]=l
但这似乎并不奏效。我将如何得到这个工作？
but this doesn't seem to be working. How would I get this to work?
THX
修改1
另外，有我可以通过只我要包含的属性的数组的方式？
edit 1
alternatively, is there a way that I can pass an array of only the attributes I want included?
推荐答案
L = Location.find（：ID =＆GT; ID，：选择=＆gt;中的名称，网址，城市：限制=＆GT; 1）
...或...
L = Location.find_by_sql（：条件=＆GT; [？选择名称，网址，城市FROM地点WHERE ID = LIMIT 1，ID]）
此引用文档给你选项的完整列表，你可以用
This reference doc gives you the entire list of options you can use with .find, including how to limit by number, id, or any other arbitrary column/constraint.
L = Location.where（[ID =？，ID]）。选择（名称，网站，城市）。第一个
参考：活动记录查询界面
您也可以交换这些链接调用的顺序，做。选择（...），其中（...）第一个 - 。所有这些调用要做的就是构造SQL查询，然后把它关闭。
You can also swap the order of these chained calls, doing .select(...).where(...).first - all these calls do is construct the SQL query and then send it off.
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