set instance variable equal to only specific model parameters - ruby-on-rails

Question

def place
#place = Activity.find(params[:id])
end
How would I choose specific params? We have activity.address1,2, zip state etc and just need an instance variable we can use which is equal to just the address attributes.

Answer 1

You could do something like:
def place
#place ||= Activity.find(params[:id])
#address_attributes = #place.attributes.slice('address_1', 'address_2', 'zip', 'state')
end
In which case you'll have an instance variable that contains a hash of the specified attributes that you might use something like:
#address_attributes['address_1']
Personally, I find typing the '' around the key values annoying and prefer using symbols. In which case you might do something like:
def place
#place ||= Activity.find(params[:id])
#address_attributes = #place.attributes.with_indifferent_access.slice(:address_1, :address_2, :zip, :state)
end
Which you would use something like:
#address_attributes[:address_1]
But, even the brackets and symbols are a little annoying. So, you might do something like:
def place
#place ||= Activity.find(params[:id])
#address_attributes = OpenStruct.new(#place.attributes.with_indifferent_access.slice(:address_1, :address_2, :zip, :state))
end
Which you could then use something like:
#address_attributes.address_1
Now, personally, I don't like that long line in the place method, so I would be tempted to do something like:
def place
#place ||= Activity.find(params[:id])
#address_attributes = get_address_attributes
end
private
def get_address_attributes
OpenStruct.new(
#place.
attributes.
with_indifferent_access.
slice(
:address_1,
:address_2,
:zip,
:state
)
)
end
Now, if this is all in a controller, and you're setting the #address_attributes variable just so that you can use it in a view, then maybe that's good enough.
But, if you're using the #address_attributes variable elsewhere in the current instance, then you might consider doing something like:
attr_accessor *%w(
address_attributes
).freeze
delegate *%w(
address_1
address_2
zip
state
), to: :address_attributes, prefix: place
def place
#place ||= Activity.find(params[:id])
#address_attributes = get_address_attributes
end
private
def get_address_attributes
OpenStruct.new(
#place.
attributes.
with_indifferent_access.
slice(
:address_1,
:address_2,
:zip,
:state
)
)
end
In which case, you could make calls like:
place_address_1
Which seems a lot nicer than something like:
#address_attributes['address_1']