Issue with Events..

[cristianotestai]

I need a suggestion to solve a particular side effect.

There are events that are quick to be executed by the user, which not required to have a screen mask to block a transaction in the application.

As an example, we have a UniEdit and UniMemo, which sets the OnKeyDown event. When the User presses the enter key, the text of UniEdit is added on the UniMemo and the text UniEdit is clear. This is a classic example ..

 

In production mainly in cases where the text to be added is relatively large and the user presses the enter key quickly more than once, is added to the UniMemo the same text several times, ie, more than one time the event was performed ... what is wrong, because when you press the Enter key, the text of UniEdit is clear after being added to the UniMemo.

How to not allow this and other cases happen?

 

Thanks

[zilav]

Javascript is asynchronous, so every time OnKeyDown event is called, browser doesn't actually add to unimemo and clear uniedit, it just generates ajax call to server. On server side you specify your actions, unigui converts them to javascript and sends it back to browser in response. And only when this generated javascript is executed, the changes happen.

Each ajax call doesn't wait for previous one to complete, so if user presses Enter quickly many times, severals ajax requests will be generated to server, each containing your current text in uniedit. Until one of them is completed and uniedit is cleared, all those requests will do the same thing - add the same text to unimemo. Thats why we need masks to prevent user from generating subsequent ajax calls until application state changes.

To make changes immediatly you'll need to write some processing logic on client side in javascript. In your case, for example, you can intercept onkeydown javascript event of uniedit and clear it from there, not on server. Or even add that text to memo and clear uniedit entirely client-side, optionally calling ajaxRequest() to inform server about changes.

[Farshad Mohajeri]

Zilav perfectly described it.

[Farshad Mohajeri]

We can add a property to button which locks it until request is completed. You can achieve same effect yourself now using client scripting.

[cristianotestai]

Javascript is asynchronous, so every time OnKeyDown event is called, browser doesn't actually add to unimemo and clear uniedit, it just generates ajax call to server. On server side you specify your actions, unigui converts them to javascript and sends it back to browser in response. And only when this generated javascript is executed, the changes happen.

Each ajax call doesn't wait for previous one to complete, so if user presses Enter quickly many times, severals ajax requests will be generated to server, each containing your current text in uniedit. Until one of them is completed and uniedit is cleared, all those requests will do the same thing - add the same text to unimemo. Thats why we need masks to prevent user from generating subsequent ajax calls until application state changes.

To make changes immediatly you'll need to write some processing logic on client side in javascript. In your case, for example, you can intercept onkeydown javascript event of uniedit and clear it from there, not on server. Or even add that text to memo and clear uniedit entirely client-side, optionally calling ajaxRequest() to inform server about changes.

 

Thanks for explanation zilav!

[cristianotestai]

We can add a property to button which locks it until request is completed. You can achieve same effect yourself now using client scripting.

 

A property for this purpose is great.. Thanks farshad.