Any chance the 2nd and 3rd lines can be combined in an one-liner and hopefully save one valuable?
def self.date_format
record = find_by_key('strftime')
record ? record.value : "%Y-%b-%d'
end
the above function in a Config model try to fetch a database record by a key, return a default if not found in database.
Even better if can be written in named scope. Thanks
As requested.
Nobody yet has mentioned try, which is perfect for this situation:
value = find_by_key('strftime').try(:value) || "%Y-%b-%d"
You could use:
(find_by_key('strftime').value rescue nil) || "%Y-%b-%d"
though using exceptions is not very efficient.
Does
value = find_by_key('strftime') || "%Y-%b-%d"
work for you?
Do you need to assign a "value" variable at all? If not...
def self.date_format
find_by_key('strftime') || "%Y-%b-%d"
end
Related
I want to mock this function:
def self.set_segment_info(segment_info, history_record)
history_record.segment_info = segment_info
end
In my test, I want a mock that only confirms that I called set_segment_info with an expected value. I don't care about what I pass in for history_record.
How would I do this? I tried
SegmentHistoryRecord.expects(:set_segment_info).with(:segment_info => expected_segment_info, :history_record => anything)
But that doesn't work.
I ran into this today and ended up doing something like:
SegmentHistoryRecord.expects(:set_segment_info).with(
expected_segment_info,
anything
)
I find it more readable that the do version and it helped me avoid a rubocop issue with too many parameters.
Here's an implementation where, if your function takes a lot of parameters, it's more convenient to specify a value for just the one you care about, instead of for all of them:
expected_segment_info = # ...
SegmentHistoryRecord.expects(:set_segment_info).with() { |actual_parameters| actual_parameters[:segment_info] == expected_segment_info }
(Where, as in the original question, set_segment_info is the function being mocked, and segment_info is the parameter whose value you want to match. Note that the history_record parameter -- and any others that might be present -- don't need to be included.)
SegmentHistoryRecord.expects(:set_segment_info).with() do |param1, param2|
# change below to your verification for :segment_info
# and leave param2 doing nothing, the expectation will ignore param2
param1 == expected_segment_info
end
Method find_something may return nil. In the following code,
something = find_something(id) ? find_something(id) : create_something(foo)
find_something(id) is called twice. This is a smell that I want to avoid. Is there a way to avoid redundancy in this expression?
Anything like this?
something = find_something(id) || create_something(foo)
There's not quite enough detail given to say this with confidence, though it might be this is a case for find_or_create_by.
If this does suit, you would just do:
something = YourModel.find_or_create_by(id: id)
You can also provide a block to this, which is passed to the create method if no record is found. For example:
something = YourModel.find_or_create_by(id: id) do |instance|
# this block only gets executed on create
instance.some_new_attribute = 'goes here'
end
Hope that's useful - let me know if it suits your use case.
My question model holds the prompt and the answer choices for questions that students can answer. It includes columns named :choice_0, :choice_1, :choice_2, :choice_3, :choice_4, and :choice_5.
In one section of my controller, I've used the following code:
correct_array.push(these_params[:choice_0]) if !these_params[:choice_0].blank?
correct_array.push(these_params[:choice_1]) if !these_params[:choice_1].blank?
correct_array.push(these_params[:choice_2]) if !these_params[:choice_2].blank?
correct_array.push(these_params[:choice_3]) if !these_params[:choice_3].blank?
correct_array.push(these_params[:choice_4]) if !these_params[:choice_4].blank?
correct_array.push(these_params[:choice_5]) if !these_params[:choice_5].blank?
In other areas of my app, I've used the #{} syntax, for example:
params[:choice_#{n}]
But that doesn't work within a params hash for some reason. I'm sure that there is a drier way to accomplish these five lines.
Thank you in advance for any insight.
A more Ruby way to do this is:
correct_array = (0..5).map { |i| these_params["choice_#{i}".to_sym] }.select(&:present?)
Or as a method:
def correct_array
(0..5).map { |i| these_params["choice_#{i}".to_sym] }.select(&:present?)
end
In either case, you have the added bonus of not having to initialize correct_array as it is created on the fly.
You may try this
(0..5).each do |i|
param_i = these_params["choice_#{i}".to_sym]
correct_array.push(param_i) if param_i.present?
end
I am new to Ruby, so let me describe the context of my problem first:
I have a json as input which has the following key / value pair:
{
"service": "update"
}
The value has many different values for example: insert,delete etc.
Next there is a method x which handles the different requests:
def x(input)
case input[:service]
services = GenericService.new
when "update"
result = services.service(UpdateService.new,input)
when "insert"
result = services.service(InsertService.new,input)
when "delete"
result = services.service(DeleteService.new,input)
....
....
else
raise "Unknown service"
end
puts JSON.pretty_generate(result)
end
What is bothering me is that I still need to use a switch statement to check the String values (reminds me of 'instance of' ugh..). Is there a cleaner way (not need to use a switch)?
Finally I tried to search for an answer to my question and did not succeed, if however I missed it feel free to comment the related question.
Update: I was thinking to maybe cast the string to the related class name as follows: How do I create a class instance from a string name in ruby? and then call result = services.services(x.constantize.new,input) , then the class names ofcourse needs to match the input of the json.
You can try something like:
def x(input)
service_class_name = "#{input[:service].capitalize}Service"
service_class = Kernel.const_get(service_class_name)
service_class.new(input).process
end
In addition you might want to check if this is a valid Service class name at all.
I don't understand why you want to pass the service to GenericService this seems strange. let the service do it's job.
If you're trying to instatiate a class by it's name you're actually speaking about Reflection rather than Polymorphism.
In Ruby you can achieve this in this way:
byName = Object.const_get('YourClassName')
or if you are in a Rails app
byName= 'YourClassName'.constantize
Hope this helps
Just first thoughts, but you can do:
eval(services.service("#{input[:service].capitalize}Service.new, #{input})") if valid_service? input[:service]
def valid_service?
w%(delete update insert).include? input[:service]
end
As folks will no doubt shout, eval needs to be used with alot of care
I have a collection of objects. There are 3 properties in each object
'id', 'name', 'is_primary'
The collection of objects will usually have anywhere from 1 to 5 objects.
What I want to do is check the collection to see if is_primary is true. If so output the name, or at least return it.
I want to do this in 1 line of code if possible. I am trying to slim up this one line for erb output in rails. Later in the page i'll output them all. I thought I had it, but if I return nil it adds extra space which shifts all the html oddly.
Thanks.
Hmm, this doesn't quite work if no element is_primary...I'm still thinking...
c.detect(&:is_primary).name
Ok, how about:
((a = c.detect(&:is_primary)) && a.name).to_s
As it happens, it is OK in an erb template for the <%= expression to return nil, that just results in an empty string, so for that case you can use:
(a = c.detect(&:is_primary)) && a.name
Update: Responding to the first comment, I do have a test case that I didn't post...
class A; attr_accessor :is_primary, :name, :id; end
t = [A.new, A.new, A.new, (a = A.new; a.name = 'xyz'; a.is_primary = true; a)]
puts (a = t.detect(&:is_primary)) && a.name
puts ((a = [].detect(&:is_primary)) && a.name).to_s
Complementing #DigitalRoss, you can also write:
collection.detect(&:is_primary).try(:name) || "default_if_no_element_or_name"
(well, to be honest I prefer Ick's maybe over Rails' try: c.detect(&:is_primary).maybe.name)
Side note: IMHO a flag that can only be active for a row it's not such a good idea. You may have inconsistent states with more than one being active and you'll have worry about it when updating (transactions, and so on). Try to store the PK reference somewhere else (a parent model? a state model?).
I want to do this in 1 line of code if possible. I am trying to slim up this one line for erb output in rails. Later in the page i'll output them all.
No need for one-liners (funny since I just wrote one): move the code to yous models or helpers as appropriate and keep your views pristine.