Overview

OGNL stands for "Object Graph Navigation Language", and it defines an entire family of key-value coding-like abilities. As Jonathan Rentzsch put it in his CAWUG presentation on Project WOnder, "Think: Key-Value Coding on Steroids". You can get more information on the specifics on OGNL at the official OGNL website.

WOOgnl provides a framework that integrates the OGNL syntax into WO's standard binding resolution. By simply including the WOOgnl framework on your build path and preceding your binding value with a "~", it will be interpreted by WOOgnl.

Here are some examples that demonstrate just a tiny bit of the really cool things you can do:

  • value="~\"Hello Mr.\" + session.user.firstName";
  • value="~name.length().(#this>100?2*#this:20+#this)";
  • value="~#A=new NSMutableArray(),#A.addObject(name),#A";

Here are some examples provided by Max Muller, WOOgnl's original author:

// Calling methods with arguments
 Repetition1: WORepetition {
       item = arrayItem;
       list = "~sort(anArray, \"name\")";
 } 

// Calling static methods
 Repetition2: WORepetition {
       item = arrayItem;
       list = "~@er.extensions.ERXArrayUtilities@sortedArraySortedWithKey(anArray, \"name\")";
 }

// Accessing static ivars
 String1: WOString {
       value = "~@ognl.webobjects.WOOgnl@OgnlSpecialCharacters";
 }

// Accessing static ivars within inner class
 String1: WOString {
       value = "~@ognl.webobjects.WOOgnl$MyInnerClass@OgnlSpecialCharacters";
 }

// Use of conditionals, note that every previous value of the . is
 // pushed into the ivar #this
 String2: WOString {
       value = "~name.length().(#this > 100? 2*#this : 20+#this)";
 }

// String concat
 String3: WOString {
       value = "~\"Hello Max \" + name";
 } 

// Use of set operator in.  can also use in against NSArray and
 NSSet objects
 String4: WOString {
       value = "~name in {\"Main\", \"Something\"} ? \"Yes\" : \"No\"";
 }

// Variable declaration.  Note that commas allow multiple actions
 // per expression.
 String5: WOString {
       value = "~#A=new com.webobjects.foundation.NSMutableArray(),#A.addObject(name), #A.addObjectsFromArray(session.languages), #A";
 }

Helper system

For more detail, check WOOGNL Helper Functions. With these two lines in your properties file and Project WONDER,

ognl.helperFunctions=true
ognl.inlineBindings=true

You can declare your own helper class like this:

public class StringHelper {
    public String capitalize(String str) {
        // ...
    }
}

And use that in your binding by "piping your data"

<wo:str value="$person.name|capitalize" />
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