Revision: 7654
Author: rj...@google.com
Date: Wed Mar 3 15:29:14 2010
Log: Added Values interface
http://code.google.com/p/google-web-toolkit/source/detail?r=7654
Modified:
/wiki/RequestFactoryPlusPaths.wiki
=======================================
--- /wiki/RequestFactoryPlusPaths.wiki Wed Mar 3 15:13:21 2010
+++ /wiki/RequestFactoryPlusPaths.wiki Wed Mar 3 15:29:14 2010
@@ -29,15 +29,15 @@
.to(myName));
}}}
-Here's what's going on. {{{ ExpensesRequestFactory }}} is an interface
generated by a JPA-aware tool that trawled through the server side domain
classes. The user then GWT.create()s an instance of it. A request factory
provides builders that can create request objects corresponding to every
service method on the server side domain layer.
+Here's what's going on. {{{ExpensesRequestFactory}}} is an interface
generated by a JPA-aware tool that trawled through the server side domain
classes. The user then GWT.create()s an instance of it. A request factory
provides builders that can create request objects corresponding to every
service method on the server side domain layer.
(The intention is that we provide the tool. Presumably we could provide
similar tools for other persistence frameworks. JPA just happens to be a
good choice for both Roo and GAE.)
-In this example, {{{ employees().findEmployee(e.getId()) }}} is creating
an instance of a request object. That's important: findEmployee() isn't an
rpc call, it's a factory call to create an instance of something like
FindEmployeeRequest. Later on that will go over the wire to be interpreted
by the server, probably as part of a batch at the end of the current
eventloop.
-
-{{{ Employee }}} is another product of our tool, and embodies the id and
properties of a server side entity class, e.g. {{{ Employee.DISPLAY_NAME
}}}. See a full fledged example of it in the blip below.
-
-{{{ requests.values.subscribe() }}} is a call to {{{
ValueStore#subscribe(Path) }}}, which does the following:
+In this example, {{{employees().findEmployee(e.getId())}}} is creating an
instance of a request object. That's important: findEmployee() isn't an rpc
call, it's a factory call to create an instance of something like
FindEmployeeRequest. Later on that will go over the wire to be interpreted
by the server, probably as part of a batch at the end of the current
eventloop.
+
+{{{Employee}}} is another product of our tool, and embodies the id and
properties of a server side entity class, e.g.
{{{Employee.DISPLAY_NAME}}}. See a full fledged example of it in the blip
below.
+
+{{{requests.values.subscribe()}}} is a call to
{{{ValueStore#subscribe(Path)}}}, which does the following:
* It establishes a subscription keyed from the last entity + property
of the path to an appropriate HasValue. In this case, myName is subscribed
to Employee e's DISPLAY_NAME.
* It fires off the request that anchors the path (findEmployee()) to
ensure the necessary property value is available, perhaps short circuiting
if such a call is already cached.
@@ -55,7 +55,6 @@
It's not hard to imagine an annotation that would cause the above to be
generated. (Pretend GWT.create() has actually been made useful and now
accepts helper arguments.)
{{{
-
class EmployeeDisplay extends Composite implements HasValue<Employee> {
private static final UiBinder UI_BINDER =
GWT.create(UiBinder.class, EmployeeDisplay.class);
@@ -73,34 +72,41 @@
DATA_BINDER.setValue(this, values, value);
}
}
-
}}}
Here's a more interesting path, to show someone's boss's name. Note that
the subscription will keyed directly to the boss entity, not to the
e.MANAGER.DISPLAY_NAME path.
{{{
-
HasValue<String> bossName = new TextField();
requests.values.subscribe(e
.newPathThrough(Employee.MANAGER)
.through(Employee.DISPLAY_NAME)
.to(bossName));
-
}}}
For list values, we assume a HasValueList interface, which looks a lot
like John L's ListHandler. (I'm cheating a bit, would really need both
display name and id in the ListBox for this to be useful, but just to get
the idea across):
{{{
-
HasValueList<String> employeeList = new ListBox();
requests.values.subscribe(
requests.employees().findAllEmployees()
.forProperty(Employee.DISPLAY_NAME)
.newPathTo(employeeList));
-
}}}
+
+When you need more than just one field for an object (or object list), the
Values<E> interface comes into play. It's basically a dedicated getter than
can wrap any object managed by the value store:
+
+{{{
+HasValueList<Values<Employee>> employeeTable = new MyTableModel();
+
+requests.values.subscribe(
+ requests.employees().findAllEmployees()
+ .forProperty(Employee.DISPLAY_NAME)
+ .forProperty(Employee.USER_NAME)
+ .newPathTo(employeeTable));
+ }}}
= Employee.java =
@@ -136,7 +142,6 @@
return version;
}
}
-
}}}
= Entity.java =
@@ -160,3 +165,12 @@
}
}}}
+= Values.java =
+
+{{{
+public interface Values<E> {
+ E getEntity();
+
+ <V, P extends Property<E, V>> V get(P property);
+}
+}}}
--
http://groups.google.com/group/Google-Web-Toolkit-Contributors
