如何将缺少的参数字段从db合并到Rails中的参数哈希

Question

Lets say the app recieves a param hash like this

 Parameters: {"utf8"=>"✓", "authenticity_token"=>"sjfsj", "user"=>{"name"=>"Joe", "mobile"=>"12345678"}, "commit"=>"Save Changes"}

and this is the user model

{name: "value", mobile: "value", email: "value", many_others: "other_values" }

What am trying to do is create a new hash with all fields combined( params + missing_fields_from_db ). So if the params has some missing keys it will be taken from model add to the new hash.

Like this:

{name: "Joe", mobile: "12345678", email: "value", many_others: "other_values" }

Is there a method available for that in ruby || rails ruby || rails ?

Thank you

Answer 1

You are looking for a Hash#merge or Hash#reverse_merge . Difference:

a = { foo: 1, bar: 2, baf: 3 }
b = { foo: 2, bar: 1, baz: 1 }
a.merge(b)
#=> {:foo=>2, :bar=>1, :baf=>3, :baz=>1}
a.reverse_merge(b)
#=> {:foo=>1, :bar=>2, :baz=>1, :baf=>3}

Note, that Hash#merge is a pure Ruby method, Hash#reverse_merge comes from Rails.