At Alpha Software, we have made our Alpha Five rapid application development software into a successful product by:
- Producing a development tool that is highly productive, extensible and programmable so that a developer never has to worry if they will run out of power;
- And by being a company that is close to its customers and is interested in moving quickly to meet customer needs.
Using our Alpha Five rapid application development software to easily add a tri-state checkbox to your app
Illustrating these points, the below verbatim exchange between Alpha developer Mike W (full name removed for privacy) and Selwyn Rabins, the President and CTO of Alpha Software, took place over the weekend. On Saturday, February 23rd at 3:09PM, Mike W wrote:OK, so I added field IsNew2 to a grid that was bound to an Access text field. (I included a copy of the screenshot below.) The checkbox is displayed along with the field value, when it’s a non-null value.
What I’m after is a tri-state checkbox so that the checkbox is checked, unchecked, or dulled. This way the user can determine which state it’s in. Furthermore, each time the user checks the box, it cycles through to the next state. In other words, just like a normal check box, but with an additional (third null) state. I use this tri-State checkbox in Access all the time, and developed one in ASP.NET based on the ImageButton. Doesn’t look like you support anything like this out of the box, or do you?
Do you use standard HTML5 checkboxes for your Alpha5 checkboxes? I ask because in HTML5 you can toggle this 3rd state of an HTML5 checkbox using javascript and I’m assuming I could run javascript code as an after render event in Alpha5, correct? Or is there an easier way to present the user with a tri-state control in Alpha 5 that I’m just overlooking?
About 2 hours later Selwyn Rabins responded with an easy solution writing, Actually, this can be done relatively easily.
In his description of the video, Selwyn wrote, "In some applications you might have a logical field in a Grid that is displayed using a checkbox. If the Grid is based on a SQL table that allows for NULL values, there are really 3 different states that the field value can have: true, false and NULL. HTML checkbox controls only have two states - checked, or unchecked, so by default the checkbox will appear unchecked for both the false and NULL state. Using Javascript, it is possible to set a checkbox state to 'indeterminate'."
In his description of the video, Selwyn wrote, "In some applications you might have a logical field in a Grid that is displayed using a checkbox. If the Grid is based on a SQL table that allows for NULL values, there are really 3 different states that the field value can have: true, false and NULL. HTML checkbox controls only have two states - checked, or unchecked, so by default the checkbox will appear unchecked for both the false and NULL state. Using Javascript, it is possible to set a checkbox state to 'indeterminate'."
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