Best way to find a single record using ActiveRecor

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' })