Rails Raise Error With Message
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Rails Exceptions
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Rails Exception Types
programmers, just like you, helping each other. Join them; it only takes a minute: Sign up Raise custom Exception with arguments up vote 19 down vote favorite 8 I'm defining a custom Exception on a model in rails as kind of a wrapper Exception: (begin[code]rescue[raise custom exception]end) When I raise the Exception, I'd like to pass rails standard error it some info about a) the instance of the model whose internal functions raise the error, and b) the error that was caught. This is going on an automated import method of a model that gets populated by POST request to from foreign datasource. tldr; How can one pass arguments to an Exception, given that you define the Exception yourself? I have an initialize method on that Exception but the raise syntax seems to only accept an Exception class and message, no optional parameters that get passed into the instantiation process. ruby-on-rails ruby exception exception-handling share|improve this question asked Jul 24 '12 at 18:15 Chris Keele 1,52011646 add a comment| 4 Answers 4 active oldest votes up vote 37 down vote accepted create an instance of your exception with new: class CustomException < StandardError def initialize(data) @data = data end end # => nil raise CustomException.new(bla: "blupp") # CustomException: CustomException share|improve this answer edited May 22 '14 at 12:58 answered Jul 24 '12 at
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Rails Custom Exception
Blocks Ruby - Modules Ruby - Strings Ruby - Arrays Ruby - rails where to put custom exceptions Hashes Ruby - Date & Time Ruby - Ranges Ruby - Iterators Ruby - File I/O Ruby rails raise internal server error - Exceptions Ruby Advanced Ruby - Object Oriented Ruby - Regular Expressions Ruby - Database Access Ruby - Web Applications Ruby - Sending Email Ruby - Socket Programming Ruby http://stackoverflow.com/questions/11636874/raise-custom-exception-with-arguments - Ruby/XML, XSLT Ruby - Web Services Ruby - Tk Guide Ruby - Ruby/LDAP Tutorial Ruby - Multithreading Ruby Useful Resources Ruby - Quick Guide Ruby - Built-in Functions Ruby - Predefined Variables Ruby - Predefined Constants Ruby - Associated Tools Ruby - Useful Resources Ruby - Discussion Ruby - Ruby on Rails Tutorial Selected Reading Developer's https://www.tutorialspoint.com/ruby/ruby_exceptions.htm Best Practices Questions and Answers Effective Resume Writing HR Interview Questions Computer Glossary Who is Who Ruby Exceptions Advertisements Previous Page Next Page The execution and the exception always go together. If you are opening a file, which does not exist, then if you did not handle this situation properly, then your program is considered to be of bad quality. The program stops if an exception occurs. So exceptions are used to handle various type of errors, which may occur during a program execution and take appropriate action instead of halting program completely. Ruby provide a nice mechanism to handle exceptions. We enclose the code that could raise an exception in a begin/end block and use rescue clauses to tell Ruby the types of exceptions we want to handle. Syntax : begin # - rescue OneTypeOfException # - rescue AnotherTypeOfException # - else # Other exceptions ensure # Always will be executed end Everything from begin to rescue is protected. If an exception occurs during the execution of this block
search `raise_error` matcher Use the raise_error matcher to specify that a block of code raises an error. The most https://www.relishapp.com/rspec/rspec-expectations/docs/built-in-matchers/raise-error-matcher basic form passes if any error is thrown: expect { raise StandardError }.to raise_error You can use raise_exception instead if you prefer that wording: expect { 3 / 0 }.to raise_exception http://phrogz.net/programmingruby/tut_exceptions.html raise_error and raise_exception are functionally interchangeable, so use the one that makes the most sense to you in any given context. In addition to the basic form, above, there are rails raise a number of ways to specify details of an error/exception: expect { raise "oops" }.to raise_error expect { raise "oops" }.to raise_error(RuntimeError) expect { raise "oops" }.to raise_error("oops") expect { raise "oops" }.to raise_error(/op/) expect { raise "oops" }.to raise_error(RuntimeError, "oops") expect { raise "oops" }.to raise_error(RuntimeError, /op/) Scenarios expect any error expect specific error match message with a string match message rails raise error with a regexp matching message with `with_message` match class + message with string match class + message with regexp set expectations on error object passed to block expect no error at all expect any error Given a file named "example_spec" with: RSpec.describe "calling a missing method" do it "raises" do expect { Object.new.foo }.to raise_error end end When I run rspec example_spec Then the example should pass expect specific error Given a file named "example_spec" with: RSpec.describe "calling a missing method" do it "raises" do expect { Object.new.foo }.to raise_error(NameError) end end When I run rspec example_spec Then the example should pass match message with a string Given a file named "example_spec.rb" with: RSpec.describe "matching error message with string" do it "matches the error message" do expect { raise StandardError, 'this message exactly'}. to raise_error('this message exactly') end end When I run rspec example_spec.rb Then the example should pass match message with a regexp Given a file named "example_spec.rb" with: RSpec.describe "matching error message with regex" do it "matches the error message" do expect { raise StandardError, "my message" }. to raise_erro
users never enter incorrect data, and resources are plentiful and cheap. Well, that's about to change. Welcome to the real world! In the real world, errors happen. Good programs (and programmers) anticipate them and arrange to handle them gracefully. This isn't always as easy as it might be. Often the code that detects an error does not have the context to know what to do about it. For example, attempting to open a file that doesn't exist is acceptable in some circumstances and is a fatal error at other times. What's your file-handling module to do? The traditional approach is to use return codes. The open method returns some specific value to say it failed. This value is then propagated back through the layers of calling routines until someone wants to take responsibility for it. The problem with this approach is that managing all these error codes can be a pain. If a function calls open, then read, and finally close, and each can return an error indication, how can the function distinguish these error codes in the value it returns to its caller? To a large extent, exceptions solve this problem. Exceptions let you package up information about an error into an object. That exception object is then propagated back up the calling stack automatically until the runtime system finds code that explicitly declares that it knows how to handle that type of exception. The Exception Class The package that contains the information about an exception is an object of class Exception, or one of class Exception's children. Ruby predefines a tidy hierarchy of exceptions, shown in Figure 8.1. As we'll see later, this hierarchy makes handling exceptions considerably easier. Figure 8.1 not available... When you need to raise an exception, you can use one of the built-in Exception classes, or you can create one of your own. If you create your own, you might want to make it a subclass of StandardError or one of its children. If you don't, your exception won't be caught by default. Every Exception has associated with it a message string and a stack backtrace. If you define your own exceptions, you can add additional information. Handling Exceptions Our jukebox downloads songs from the Internet using a TCP socket. The basic code is simple: opFile = File.open(opName, "w") while data = socket.read(512) opFile.write(data) end What happens if we get a fatal error halfway through the download? We certainly don't want to store an incomplete song in the song list. “I Did It My *click*”. Let's add some exception handling code and see how it helps. We enclose th