Re: [Laszlo-user] Extending Dataset Class in 3.1.1

Henry Minsky Wed, 04 Jan 2006 12:47:33 -0800

Even if the LZX compiler doesn't support it via the XML syntax, I think you can extend a class via the underlying script class declaration mechanism.

Something like

var MyDataset = Class( "MyDataset" , LzDataset );

Then you can define methods on the class with

MyDataset.prototype.somemethod = function (...) { }

Then you can instantiate this with new MyDataset();

You have to manually add event handlers though.

On 1/4/06, Bryan Barkley <[EMAIL PROTECTED]> wrote:

Since extending datasets doesn't seem to be supported can anyone offer any suggestions for handling common operations across datasets such as the situation David describes?

Subclassing dataset could also be useful to provide default error handling behavior as well as changing the root src attribute as described in this forum thread: http://www.laszlosystems.com/developers/community/forums/showthread.php?s=&threadid=2219

All of these cases are aspects that would be somewhere between difficult and inconvenient to maintain if they can't be factored into a common code location.

I have tried nesting datasets in a datasource that had onerror and ondata handlers; that didn't seem to work. The only other thing I can think of is finding all datasets at startup and programmatically registering event handlers with them. This seems pretty hackey.

Anyone have a good solution?

Thanks,
   Bryan

On 1/3/06, Buckler, David <[EMAIL PROTECTED]> wrote:

Thats a very interesting idea and I could see how that could cross the streams. The reason why I am trying to extend the dataset is to overload the doRequest() to include user name/password query parameters for authentication on every request. So unfortunately a local dataset wont fix my problem but thanks for the help.

David

From: Henry Minsky [mailto:[EMAIL PROTECTED]]
Sent: Tuesday, January 03, 2006 2:04 PM
To: Buckler, David
Cc: [email protected]
Subject: Re: [Laszlo-user] Extending Dataset Class in 3.1.1

This might be some fallout from the change which added "local datasets" to the compiler.

You can now say put datasets inside of instances or classes like below. I wonder if
local datasets might be able to be used in your application instead of extending dataset?

<view name="somedata" layout="axis: y" bgcolor="#cccccc">
    <method event="onclick">
        Debug.write(this.lds);
    </method>
    <dataset name="lds">
        <foo>bar</foo>
    </dataset>
    <text>local dataset</text>
    <method reference="lds" event="oninit">
      <![CDATA[
      Debug.write("somedata test data loaded", this);
      if (this.lds.serialize() != '<lds><foo>bar</foo></lds>') {
      Debug.error("somedata serialized data does not match expected value");
      }
      ]]>
    </method>
</view>

On 1/3/06, Buckler, David <[EMAIL PROTECTED]> wrote:

In 3.0.2 I was be able to extend the dataset class, albeit with a load of compilation warnings, but it would still work. Now I am moving to 3.1.1 and this "feature" no longer works. Any ideas?

<canvas>

<class name="myds" extends="dataset"/>

<myds name="z">
    <node>Hello Moto</node>
</myds>

<text datapath="z:/node/text()"/>

</canvas>

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--
Henry Minsky
Software Architect
[EMAIL PROTECTED]

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--
Henry Minsky
Software Architect
[EMAIL PROTECTED]

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Re: [Laszlo-user] Extending Dataset Class in 3.1.1

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