Setting up XML DS for DataSource.performCustomOperation()

[mduduzik]

1) How do I set up an an XML datasource to support this method. If there's an example/sample; that'll much appreciated.

2) We are currently using SmartGWT Pro 2.1 - we do not have access to this method, yet. Is there a sample/example on how we can accomplish the same feature of our existing XML based datasource. BTW - we are using serverType="generic" and lookup style of "New".


Thanks.

[Isomorphic]

What are you trying to accomplish? performCustomOperation() is usually something you'd use for SQL, but you're using DMI.

[mduduzik]

Thanks for a prompt reply. I'm using DMI to call a (@Service method) e.g. to send an email or JMS message etc. The most convenient way I could think of is to simply add a custom method to an already existing DS and DMI class (on top of CRUD methods).

Is there another way to accomplish this?

Thanks!

[Isomorphic]

It's reasonable to represent that as an operation of type="custom", however, while performCustomOperation is still being added, you can also just use an operationBinding with operationType="fetch" and invoke it via DataSource.fetchData().

[mduduzik]

Thanks! It sounds like you're suggesting the ff. pattern in the short term:

1. Create a regular DMI DS (e.g. assetDS in assetDS.ds.xml) for CRUD operations; and then

2. Create a 'Service' DMI DS (e.g. assetServiceDS in assetServiceDS.ds.xml) for service methods, and override 'fetch' operationId that maps to a service method - as you suggested in your previous note. Then call this method from assetServiceDS.fetchData().

The reason I'm going this way is that I cannot have more than one 'fetch' operationBinding's in the same DS. Or can I?

[Isomorphic]

You can have multiple operstionBindings for the same operationType so long as they have different operationIds. So you don't need a separate DS unless you choose to do so for organizational purposes.

[ls3674]

So if I have a method in my datasource called say doFoo(), I would then add it to my ds.xml with a type="custom" and a name="doFoo"?

Let's say I want doFoo to return void, do I still need to pass around dsResponses etc.?

The call from the client is a bit confusing in this instance as well. For example would I call DataSource.performCustomOperation("doFoo")?

There is only one signature on the performCustomOperation and it requires a String, Record, DSCallBack, DSRequest).

How can I just call the doFoo method with a button click?

Thanks,

[Isomorphic]

You declare an <operationBinding> and include a <serverObject> like with any DMI. Set operationType="custom" on the <operationBinding>. The first parameter to performCustomOperation is the operationId you put on the <operationBinding>. You can pass null for the Record parameter if you don't want to send any data to the server. You are not required to return a dsResponse.

[ls3674]

Thanks for the quick response. To clarify a little further:

The performCustomOperation api is as follows:

public void performCustomOperation(String operationId,
Record data,
DSCallback callback,
DSRequest requestProperties)

I know what to pass for the operationId and the record (null) but what about the other two parameters (DSCallBack and DSRequest)?

The use case I'm targeting does not require a callback or dsrequest. I just want to start a process on the server. The only thing the client should care about in this case is a successful rpc call.

Thanks

[Isomorphic]

If you don't need to use either of those parameters, you can pass nulls for those as well. However you mentioned being notified of success - that's what the callback is for.

[ls3674]

Great, thanks. I've implemented it on the client, but I get the following error when I try to invoke the method....

"Uncaught exception escaped : com.google.gwt.event.shared.UmbrellaException
One or more exceptions caught, see full set in UmbrellaException#getCauses
See the Development console log for details.
Register a GWT.setUncaughtExceptionHandler(..) for custom uncaught exception handling"

I'm not using Eclipse, so the development console isn't handy (is there a way to see this in the SmartGWT developer console?).

My DS.xml file is as follows:

<DataSource ID="logType" serverConstructor="com.isomorphic.jpa.JPA2DataSource" beanClassName="com.sncorp.gs2.jee.entities.protolog.LogType">
<fields>
<field name="name" type="text" title="name"/>
<field name="logtypeId" title="Log Type Id"/>
</fields>
<dropExtraFields>true</dropExtraFields>
<serverObject className="com.sncorp.gs2.ui.server.LogTypeDMI"/>
<operationBindings>
<!--<operationBinding operationType="fetch" serverMethod="fetch"/>-->
<operationBinding operationType="add" serverMethod="add"/>
<operationBinding operationType="update" serverMethod="update"/>
<operationBinding operationType="remove" serverMethod="remove"/>
<operationBinding operationType="custom" operationId="startLogThread" serverMethod="startLogThread">
<serverObject className="com.sncorp.gs2.ui.server.LogTypeDMI"/>
</operationBinding>
</operationBindings>
</DataSource>

DataSource instantiation in client code:
//set the datasource object(s) for this component
dsLogTypes = DataSource.get("logType");

Custom method invocation:
IButton ibtn = new IButton();
ibtn.setID("ibtnTest");
ibtn.setTitle("Test");
ibtn.addClickHandler(new ClickHandler()
{
@Override
public void onClick(ClickEvent clickEvent)
{
dsLogTypes.performCustomOperation("startLogThread",null,null,null);
}
});

DMI call server side:

public DSResponse startLogThread()
{
//create an empty DSResponse to send back to the client
DSResponse dsResponse = new DSResponse();
System.out.println("\n\n\n\n\nRPC MADE IT\n\n\n\n\n");
try
{

dsResponse.setSuccess();
//spawn the new thread and have it pump messages to a queue or subscription
new Thread(new Runnable()
{
@Override
public void run()
{
while(true)
{
try
{
Thread.sleep(1000);
System.out.println("\n\n I DID SOMETHING \n\n");
}
catch(InterruptedException ie)
{
System.out.println("thread interrupted");
}
}
}
}).start();
}
catch(Exception ex)
{
ex.printStackTrace();
}
return dsResponse;
}

[ls3674]

Trapping the error produces the following message btw:

"Invoking an instance method on a null reference"

I'm not sure how the data source is null. The fetch method works fine to populate a ComboBoxItem

[Isomorphic]

Sorry, we indicated you could pass null for the Record param, in reality you need to pass an empty Record (just new Record() will do).

[ls3674]

It appears that the only parameter that can be null is the callback. I got the same issue until I passed an instance of a DSRequest as well. Can you confirm?

dsLogTypes.performCustomOperation("startLogThread", new Record(), null, new DSRequest());

Thanks

[Isomorphic]

We'll allow both parameters to be null in the future. Thanks for pointing this out.