问题
Where I used to do this:
Foo.find_by_bar('a-value')
I can now do this:
Foo.where(:bar => 'a-value').limit(1).first
Is this recommended? Is this the best way? Should I continue to use the "old" way because it continues to be useful syntactic sugar, or is there an Even Better way I can do that now, which will support chaining and all the other good stuff?
回答1:
Rails 4 :
Foo.find_by bar: 'a_value' , wibble: 'a wibble value'
回答2:
I think the preferable way to return a single record would be along the lines of your second example, but you can omit the limit part:
Foo.where(:bar => 'a-value').first
This follows the new syntax and supports chaining if you want to add more conditions to the lookup.
回答3:
Rails gives you a whole load of magic methods for this kind of thing:
Foo.find_by_bar('a-value')
You can also use multiple attributes:
Foo.find_by_bar_and_wibble('a foo value', 'a wibble value')
And appending a ! causes it to throw a RecordNotFound if nothing's found:
Foo.find_by_bar!('a-value')
回答4:
Other alternative:
Foo.find(:first, conditions: { bar: 'a-value' })
You can also use multiple attributes:
Foo.find(:first, conditions: { bar: 'a-value' , wibble: 'a wibble value' })
来源：https://stackoverflow.com/questions/6326440/best-way-to-find-a-single-record-using-activerecord-3-arel