问题
I'm new to rails and this might seem obvious, but couldn't find a answer.
when i do
u = User.where("email=?", email_string)
u.name = "new name"
doesn't work i keep getting
NoMethodError: undefined method `name=' for #<ActiveRecord::Relation:0x1049c2890>
but if i change
u = User.where("email=?", email_string)
to
u = User.find_by_email(email_string)
i can see my changes being persisted and no error thrown.
So what am i missing. is it that .where returns a read only object or something ?
回答1:
.where is actually a scope and indeed returns a collection of Users and not a single one. You can obtain the first matching user (as .find_by_email does) with
User.where('email = ?', email_string).first
Additionally, you can return a collection with
User.find_all_by_email(email_string)
I hope this helps.
来源：https://stackoverflow.com/questions/7442791/where-vs-find-activerecordrelation-nomethoderror