Tips

Power of objects and dot notation

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With 4D v17 R5, we showed you how easy it is to manipulate an object to retrieve the attributes of a file or folder. Things have gotten even easier thanks to object notation! In this blog post, we’re providing you an HDI with a user interface to manage files and folders. This isn’t new in 4D since you could do it with classic 4D commands, but now you can do it easier and with fewer lines of code!

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Object notation to handle files and folders

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4D already provides commands to handle files and folders, but what about new commands that take advantage of the power of object notation?

Objects have changed the way many 4D developers write code, making it more generic, flexible, easier, and faster. Now this wave of change is extended to files and folders. In this blog post, we’ll show you how easy it is to manipulate an object in order to retrieve the attributes of a file or folder (rather than calling several commands and storing the information in multiple variables). Things are getting a lot easier!

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Read 4D object fields with SQL Engine

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A 4D object field is a persistent database field type, stored as binary content. Previously, reading this type of field by an ODBC driver wasn’t possible. Until today.

Before, an error was returned when trying to read an object field. This prevented the completion of simple Select * from myTable requests, which could be frustrating for users who only wanted to browse the content of a table.

Good news! The SQL engine has been updated to allow 4D object fields to be read.

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Get info about the running application

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4D v17 R3 takes your database analysis a step further by enabling you to create a customized server administration dialog. Following the ability to retrieve information about users & processes, getting all runtime information about 4D Web server, getting details about the active license, and getting all of the hardware and system details, you now also have the ability to retrieve the activity and network configuration of the running database.

Do you need to know on which IP address and port the database is listening, if communications between the client and the server are encrypted, or if the legacy network layer is used? Just call the new command, Get application info. And that’s not all! This command also returns information about the database such as: the amount of CPU used, the time since its been started, and the list goes on.

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Convert classic 4D forms to dynamic forms

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Your forms may need to be changed depending on your customer or user needs. For example, the color black might be perfect for one user but not so much for another user (who sees blue as the ultimate perfection). Luckily, dynamic forms (introduced with 4D v16 R6) are here to help you handle your users’ preferences. But rewriting an existing form to a dynamic form could be a difficult task, and it’s not always easy to start with a blank page. Ideally, it’d be best to have a draft that can be modified and improved. With 4D v17 R3, it’s now possible to easily convert a classic 4D form (stored in .4DB file) to a dynamic form.

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Write your own methods for objects

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A new command is at your disposal allowing you to use formulas in your code. You can now encapsulate them in objects and call them when needed. There’s no more need to write your code as text. Now you can just pass your formula in your command and that’s it! This is a great addition, since your code isn’t text, you can benefit from Syntax highlighting and all the other advanced functionalities of the code editor!

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Times inside objects… (and everywhere else)

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Objects are at it again, continuing to demonstrate their utility to ease your life as a developer.

Using time (or duration) values inside of objects is now smoother and more intuitive. Beginning with 4D v17, times inside objects are set as seconds  – and not milliseconds!

Tips New collection

How to display a multilevel collection in different list boxes!

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Starting with 4D v17, the content of a multilevel collection can easily be displayed in different list boxes. Meaning that you can bind several list boxes to display nested details … without a single line of code! This can be achieved by simply using an object or a collection as the data source for another list box!

With the new list box collection type, the “Current item” and “Selected items” properties have been added. Keep in mind that the “Current item” property allows you to get an object, while the “Selected item” property returns a collection.