Modify strings in Rails?

Question

Hey everyone,

So I'm new to Rails (teaching myself as a senior project in high school), and I'm trying to figure out how to modify these strings.

Let's say someone writes the following string in a form: "you know you are a geek when"

How can I automatically change it to this: "You know you are a geek when..."?

I need Rails to check the case of the first letter and check for the three dots then modify the string as necessary. I've looked here, but I can't find anything that would work.

Thanks a lot!

EDIT: I'm trying to implement what Reuben Mallaby suggested, but I'm having trouble. Here's the relevant part of the lists_controller.rb file, and below that is the method in the list.rb model.

def update
  @list = List.find(params[:id])
  @list.fixlistname
  respond_to do |format|
    if @list.update_attributes(params[:list])
      flash[:notice] = 'List was successfully updated.'
      format.html { redirect_to(@list) }
      format.xml  { head :ok }
    else
      format.html { render :action => "edit" }
      format.xml  { render :xml => @list.errors, :status => :unprocessable_entity }
    end
  end
end

and..

def fixlistname
  new_title = title.humanize + (title.ends_with("...") ? "" : "...")
end

EDIT 2: I want the string to be modified before it goes into the database, and this is the error message I'm getting:

undefined method `ends_with' for "You know you are a track runner when":String

GOT IT WORKING! THANKS EVERYONE!

Answer 1

You could use humanize to make sure that the first letter is uppercase and ends_with?("...") to check for the three dots

new_string = my_string.humanize + (my_string.ends_with?("...") ? "" : "...")

Answer 2

The way to inspect and modify strings with ruby is to use regular expressions. You can read about them here, and learn to use them at Rubular

Answer 3

String#capitalize will capitalize the first letter of a string:

"you know you are a geek when".capitalize # => "You know you are a geek when"

And can get the last three characters of a string using String#[]:

"you know"[-3,3]             # => "now"
"you know..."[-3,3]          # => "..."

"you know..."[-3,3] == "..." # => true

Rails also provides a nice shortcut for this in the form of String#ends_with?:

"you know...".ends_with?("...") # => true

So you can check the end of the string, and if it isn't "...", you can append "...":

dots = "..."
my_str = "you know you are a geek when"

my_str = my_str + dots unless my_str.ends_with? dots
# => "you know you are a geek when..."

my_str.capitalize!
puts my_str
# => "You know you are a geek when..."

One edge case you may want to consider, though, is if the string ends with periods, but not three of them. For example, how will you handle a string like "you know.." (the above method would make this "You know.....") or "you know....." (the above would leave this unchanged)?

Answer 4

Just a tip, but when you perform "destructive" operations (operations that modify the calling object) you should add a exclamation mark (!) to the end of the method name. It's just a convention, but it definitely increases readability, and decreases surprise gotchas later on.

So in your controller you would have:

@list.fixlistname!

and in your model you would have:

def fixlistname!
  new_title = title.humanize + (title.ends_with?("...") ? "" : "...")
end

See here for more info.