.net code 39 reader

.net code 39 reader

.net data matrix reader, qr code reader library .net, .net data matrix reader, .net barcode reader, .net code 128 reader, .net code 39 reader, integrate barcode scanner into asp net web application, .net code 128 reader, .net code 128 reader, .net code 39 reader, data matrix reader .net, .net ean 13 reader, .net pdf 417 reader, barcode reader integration with asp.net, .net ean 13 reader

vb.net pdfwriter, convert pdf to word c#, vb.net compress tiff image, vb.net pdf 417 reader, asp.net open pdf in new window code behind, convert tiff to gif c#, asp.net barcode reader, datamatrix.net documentation, asp.net generate barcode 128, .net tiff to jpg

You might be wondering what would happen if you tried to save a new event without giving it any information. Go ahead and try doing that. You ll see that Rails doesn t care. In fact, it s the Event model that doesn t care. This is because in Rails, the rules for data integrity (such as required fields) are the responsibility of the model. To add basic validation for required fields, open the Event model in app/models/ event.rb and add the validator methods shown in Listing 3-5 inside the class body.

Methods are little programmable actions that you can define to help your development. Let s leave irb for the moment and talk about pure Ruby code. (All of this also works if you type it into irb.) Suppose that, several times in the application you re writing, you need to get the current time as a string. To save yourself from having to retype Time.now.to_s over and over, you can build a method. Every method starts with def: def time_as_string Time.now.to_s end Anywhere in the application that you want to get the time, you say time_as_string: puts time_as_string "2010-04-05 20:55:21 +0000" See how easy that is Methods can also take in variables: def say_hello_to(name) "Hello, #{name}!" end

birt gs1 128, word 2010 ean 13, birt data matrix, birt barcode free, word data matrix font, upc-a word font

So far in this chapter, we ve covered the primary built-in data classes of numbers, strings, arrays, and hashes. These few types of objects can get you a long way and will be used in all your programs. You ll be looking at objects in more depth in 6, but before you get that far, there are a few other important points you need to look at first.

A concept that s useful to represent within many computer programs is time, in the form of dates and times. Ruby provides a class called Time to handle these concepts. Internally, Time stores times as a number of microseconds since the UNIX time epoch: January 1, 1970 00:00:00 Greenwich Mean Time (GMT)/Coordinated Universal Time (UTC). This makes it easy to compare times using the standard comparison operators, such as < and >. Let s look at how to use the Time class: puts Time.now

Save the file and try creating an empty event again. Instead of saving the record, Rails will display a formatted error message, as shown in Figure 3-5.

Thu Apr 16 00:00:00 +0100 2009 Time.now creates an instance of class Time that s set to the current time. However, because you re trying to print it to the screen, it s converted into the preceding string. You can manipulate time objects by adding and subtracting numbers of seconds to them. For example: puts Time.now puts Time.now - 10 puts Time.now + 86400

puts say_hello_to("John") "Hello, John!" Next, you learn how to put methods together into groups to make them really powerful.

If you ve done any web development before, you know that validating fields is a major nuisance. Thankfully, Rails makes it easy.

C ha p ter 3 r U B Y S B U ILDI NG B LO C K S : D a t a , e X p r e S S I O N S , a N D F LO W C O N t r O L

Thu Apr 16 00:00:00 +0100 2009 Wed Apr 15 23:59:50 +0100 2009 Fri Apr 17 00:00:00 +0100 2009 In the first example, you print the current time, and then the current time minus 10 seconds, and then the current time with 86,400 seconds (exactly one day) added on. Because times are so easy to manipulate, some developers extend the Fixnum class with some helper methods to make manipulating dates easier: class Fixnum def seconds self end def minutes self * 60 end def hours self * 60 * 60 end def days self * 60 * 60 * 24 end end puts puts puts puts Time.now Time.now + 10.minutes Time.now + 16.hours Time.now - 7.days

convert base64 image to pdf javascript, jspdf jpg to pdf, convert excel to pdf java source code, java code to extract text from pdf