Is it ok to use struct as constants in initializer?

Rails
1

I want to define simple global objects that contain a code and
description for custom errors. Is it a bad idea to use structs in an
initializer in the app?

api_error_constants.rb in /config/initializers

error_type = Struct.new(:code, :description)
BAD_JSON = error_type.new(“001” , “Problem parsing JSON”)
BAD_XML = error_type.new(“002” , “Problem parsing XML”)
…
…

Or is there a more appropriate/standard way?

2

On Thu, Nov 29, 2012 at 3:47 AM, comopasta Gr [email protected]
wrote:

error_type = Struct.new(:code, :description)
BAD_JSON = error_type.new(“001” , “Problem parsing JSON”)
BAD_XML = error_type.new(“002” , “Problem parsing XML”)

class MyClass
class APIParseError < StandardError
def initialize(code, lib)
@code = code
@lib = lib
end

def to_s
  "#{@code}: Problem parsing #{@lib}"
end

end
end

raise(MyClass::APIParseError.new(“001”, :XML))
#=> MyClass::MyError: 001: Problem parsing XML

3

On Thu, Nov 29, 2012 at 4:11 AM, Jordon B. [email protected]
wrote:

raise(MyClass::APIParseError.new(“001”, :XML))
#=> MyClass::MyError: 001: Problem parsing XML

This would actually display: “MyClass::APIParseError” I had a
misspelling since I didn’t run it through an REPL to get the output I
just wrote it so of course typos can happen but it will show you the
right error class when you output it.

4

Ok, I would remove my previous post if I could but I can’t access it
anymore.

In any case. I have improved that code to a better version where I rely
on raise and rescues to handle exceptions generated by the module. No
more ugly if xxxx != false

Anyway my question was not about how to generate exceptions but about
the fact of using a struc in my initializers.

I would delete the whole thread anyway…

5

Jordon B. wrote in post #1087053:

On Thu, Nov 29, 2012 at 3:47 AM, comopasta Gr [email protected]
wrote:

error_type = Struct.new(:code, :description)
BAD_JSON = error_type.new(“001” , “Problem parsing JSON”)
BAD_XML = error_type.new(“002” , “Problem parsing XML”)

class MyClass
class APIParseError < StandardError
def initialize(code, lib)
@code = code
@lib = lib
end

def to_s
  "#{@code}: Problem parsing #{@lib}"
end

end
end

raise(MyClass::APIParseError.new(“001”, :XML))
#=> MyClass::MyError: 001: Problem parsing XML

Thanks Jordon. I wanted to keep my question simple but maybe it needed
more details. Sorry I have to paste a bunch of code…

I need to respond with the api using json:

{
“result”: {“created”:“0”,“failed”:“0”},
“errors”:[
{“error”:{“message”:“Problem parsing JSON”,“code”:“001”}}
]
}

I use Rabl to generate the json I give back. Rabl works well with
openStruct. There can be several errors to be reported.

The controller delegates to a module this and other validations on the
json.

Relevant code from the controller:

@result = OpenStruct.new
@errors = []

entries = ApiUtilitiesV1::validateJson(request.body.read)
if entries != false
…keep processing, might add elements to the @errors array
else
err = ApiUtilitiesV1::getError(BAD_JSON)
@errors << err
end

@result.created = “#{created_counter}”
@result.failed = “#{failed_counter}”
render ‘create’ → renders Rabl template using @result and @errors

In the module where I have the api utilities there is:

def self.validateJson(json_string)
begin
parsed_vals = JSON.parse(json_string)
return parsed_vals[“entries”]
rescue JSON::ParserError
return false
end
end

def self.getError(error_constant)
error = OpenStruct.new
error.message = error_constant.message
error.code = error_constant.code
return error
end

The idea is to share the error codes defined in the structs between the
controller and the module. And also have a single method that provides
me with the data that goes in for each different error.

So I’m not sure how can I incorporate your suggestion into the logic I
have. Or maybe the logic I have is completely a bad idea…

6

On 30 November 2012 13:01, comopasta Gr [email protected] wrote:

I would delete the whole thread anyway…
This is a mailing list not a forum (though you may be accessing via a
forum like interface). Emails cannot be deleted by the sender. Once
it is on my machine only I can delete it (I hope, otherwise I am in
trouble).

Colin