I have a two mailers
welcome_manger(user) welcome_participant(user)
Both send different information and have different layouts.
when I call the deliver method I would like to use something like the following
UserMailer.welcome_self.role(self.user)
This does not work. How can I accomplish this?
Something like this perhaps:
m = 'welcome_' + self.role
UserMailer.send(m.to_sym, [self.user])
Assuming that self.role returns a String.
The send method invokes a method by name:
obj.send(symbol [, args...]) → obj
Invokes the method identified by symbol, passing it any arguments specified.
So you just need to build the appropriate method name as a string and then convert it a symbol with to_sym.
Related
Im pretty new to ruby . I have a method lets say -" method_X " with parameters (client_name, client_dob).
def method_X client_name, client_dob
(BODY OF THE METHOD)
end
Now I want to introduce a third parameter let's say "client_age". I want my method_X to have a flexibility in taking the parameters.I'm getting an error to mandatorily enter client_name if I forget. I should have flexibility to not mandatorily enter all the three parameters as input. How can I achieve this? Thank you in advance!
In Ruby, you can declare parameters as required, default and optional arguments.
required - required parameters need to be passed otherwise it throws an error.
Ex: def method_X(client_name)
In this, you need to send the client_name argument, else it throws an error.
default - default parameters are optional arguments, but you should declare the default value for the given parameter while defining the method. So that you can skip the argument if you want or you can send a new value while calling the method.
Ex: def method_X(client_name="Abc Company")
In this case, if you haven't passed the client_name argument for the method, the default will be Abc Company. You can default to any value you like, say nil, empty string, array etc.
optional - Optional parameters where you need to use the splat(*) operator to declare it. This operator converts any number of arguments into an array, thus you can use it if you don't know how many arguments you will pass. If no arguments, it gives an empty array.
Ex: def method_X(*client_name)
I have a method that looks like this:
> rating
=> "speed"
Then I have a call that looks like this:
profile.ratings.find_by(user: current_user).speed
What I want to do is pass the value of rating to that call.
But when I do this:
profile.ratings.find_by(user: current_user).rating
It doesn't work, because there is no method called rating on each ratings object.
This is the error I get when I run the above:
Rating Load (4.5ms) SELECT "ratings".* FROM "ratings" WHERE "ratings"."profile_id" = $1 AND "ratings"."user_id" = 7 LIMIT $2 [["profile_id", 12], ["LIMIT", 1]]
NoMethodError: undefined method `rating' for #<Rating:0x007fca0c4fba90>
I would normally do string interpolation, except now I am working on a method call.
How might I do this?
If you're looking to access a property on an ActiveRecord model they provide a simple accessor:
profile.ratings.find_by(user: current_user)[rating]
This is safer than the send method since it's only going to fetch attributes. If you had a method called ban_and_charge_ten_bucks! some hostile user might be able your system into calling that if you call send without checking what you're calling.
You can use the send method
profile.ratings.find_by(user: current_user).send(rating)
I am a little lost here.
Given the following method:
[ODataRoute("MktInstrument(Symbol={symbol})")]
public MktInstrument MktInstrument(string symbol) {
I call it using a URL in the form of:
http://localhost/MktInstrument(Symbol='FOREX!EURxUSD')
That is nice - but the variable symbol now includes the ' that wrap the parameter.
if I put that into the template
[ODataRoute("MktInstrument(Symbol='{symbol}')")]
I get an error that the template is not valid.
If I call it witout the warapping
http://localhost/MktInstrument(Symbol=FOREX!EURxUSD)
then the method is not called. Am I really supposed to remove the '' around the string parameter myself or am I missing something?
In your controller, you can make the action method like "public IHttpActionResult Function([FromODataUri]string symbol)" which means you add attribute [FromODataUri], it will not have single quotes. You can refer to http://odata.github.io/WebApi/#04-06-function-parameter-support, the related statement is
‘[FromODataUri]’ is mandatory for complex, entity and all collection. However, it is optional for Primitive & Enum. But for string primitive type, the value will contain single quotes without ‘[FromODataUri]’.
I'm using xml-mapping in Ruby (on Sinatra) for some XML stuff. Generally I follow this tutorial: http://xml-mapping.rubyforge.org/. I can create objects and write them to XML strings using
login.save_to_xml.to_s
But when I try
login = Login.load_from_xml(xml_string)
I get the following error:
XML::MappingError - no value, and no default value: Attribute username not set (XXPathError: path not found: username):
Here is the XML string I receive:
<login><username>ali</username><password>baba</password></login>
This is what the class looks like:
class Login
include XML::Mapping
text_node :username, "username"
text_node :password, "password"
end
So the class name is the same, the nodes are named the same. I actually get the exact same string when I create an instance of my object and fill it with ali/baba:
test = Login.new
test.username = "ali"
test.password = "baba"
p test.save_to_xml.to_s
<login><username>ali</username><password>baba</password></login>
What am I missing?
Thanks,
MrB
EDIT:
When I do
test = login.save_to_xml
And then
login = Login.load_from_xml(test)
it works. So the problem seems to be that I'm passing a string, while the method is expecting.. well, something else. There is definitely a load_from_xml(string) method in the rubydocs, so not sure what to pass here. I guess I need some kind of reverse to_s?
It looks like you save_to_xml creates a REXML::Element. Since that works, you may want to try:
Login.load_from_xml(REXML::Document.new(xml_string).root)
See the section on "choice_node" for a more detailed example http://xml-mapping.rubyforge.org/
I'm working on converting code from Ruby to Node.js. I came across these lines at the end of a function and I'm curious what the original developers were trying to accomplish:
url = url.gsub "member_id", "member_id__hashed"
url = url.gsub member_id, member_id_hashed
url
I'm assuming that url at the end is Ruby's equivalent to return url;
as for the lines with gsub, from what I've found online that's the wrong syntax, right? Shouldn't it be:
url = url.gsub(var1, var2)?
If it is correct, why are they calling it twice, once with quotes and once without?
gsub does a global substitute on a string. If I had to guess, the URL might be in the form of
http://somewebsite.com?member_id=123
If so, the code has the following effect:
url.gsub "member_id", "member_id__hashed"
# => "http://somewebsite.com?member_id__hashed=123"
Assuming member_id = "123", and member_id_hashed is some hashed version of the id, then the second line would replace "123" with the hashed version.
url.gsub member_id, member_id_hashed
# => "http://somewebsite.com?member_id__hashed=abc"
So you're going from http://somewebsite.com?member_id=123 to http://somewebsite.com?member_id__hashed=abc
Documentation: https://ruby-doc.org/core-2.6/String.html#method-i-gsub
I'm assuming that the url at the end is Ruby's equivalent to return url;
If that code is part of a method or block, indeed, the line url is the value returned by the method. This is because by default a method in Ruby returns the value of the last expression that was evaluated in the method. The keyword return can be used (as in many other languages) to produce an early return of a method, with or without a return value.
that's the wrong syntax, right? shouldn't it be
url = url.gsub(var1, var2)?
The arguments used to invoke a method in Ruby may stay in parentheses but they may, as well, be listed after the method name, without parentheses.
Both:
url = url.gsub var1, var2
and
url = url.gsub(var1, var2)
are correct and they produce the same result.
The convention in Ruby is to not put parentheses around method arguments but this is not always possible. One such case is when one of the arguments is a call of another method with arguments.
The parentheses are then used to make everything clear both for the interpreter and the readers of the code.
If it is correct, why are they calling it twice, once with quotes and once without?
There are two calls of the same method, with different arguments:
url = url.gsub "member_id", "member_id__hashed"
The arguments of url.gsub are the literal strings "member_id" and "member_id__hashed".
url = url.gsub member_id, member_id_hashed
This time the arguments are the variables member_id and member_id_hashed.
This works the same in JavaScript and many other languages that use double quotes to enclose the string literals.
String#gsub is a method of class String that does search & replace in a string and returns a new string. It's name is short of "global substitute" (it replaces all occurrences). To replace only the first occurrence use String#sub.