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.
Imagine that your database contains several tables of types or categories. These tables are very simple, often with only an identifier and a text field. For demonstration purposes, let’s say it’s a shoe management database. To qualify the products, we need to define their type, color, pattern, material, season and so on.
It’s cumbersome to manage each of these tables in a list form and an input form and associated methods. In this case, the use of a generic form is essential to avoid duplication and simplify maintenance.
ORDA provides a great feature to channel data through filters and get aggregated values, by including a set of easily-understood aggregation operations that examine and perform calculations on the data sets. For example, the sum, average, count, min, and max methods are used to perform the operations which their names describe!
4D v17 goes a step further to let you create a customized server administration dialog. Following the ability to retrieve information about users & processes, getting all runtime information about 4D Web server, as well as details about the active license, you now have the ability to also retrieve all of the hardware and system details for the machine running your 4D server.
Do you need to know what OS is being used, what processor(s), how much RAM is available, etc.? Just call the new Get system info command, locally or remotely! And that’s not all, this command can be extremely useful for quickly diagnosing and solving any problems that may arise.
The ORDA series continues! In this blog post we’ll see how to use logical operators on entity selections!
These operations allow you to get intersections, unions, or differences between two entity selections like you can with classic 4D sets.
FIRST RECORD, LAST RECORD, NEXT RECORD, PREVIOUS RECORD; does that ring any bells? I bet it does. You’ve already been using them to handle selections! ORDA provides useful and familiar methods to navigate through entities in an entity selection – and obviously, some perks!
For starters, you can handle several entity selections at the same time and navigate through them independently, whereas normally you can only manage a single ‘current selection’ per table. That’s precisely what we’re going to see in this blog post.
4D v17 introduces ORDA, a major evolution in 4D which is opening a world of new possibilities for 4D developers. One of the benefits of using ORDA is related to record locking, because ORDA offers a choice between optimistic and pessimistic locking. After having introduced the ORDA locking mechanisms, we continue the ORDA series so you can discover how to work efficiently with optimistic locking with ORDA.
The ORDA series continues! In this blog post, we’ll look at how you can use locks in your databases with ORDA concepts! It’s not uncommon to need to manage conflicts that might occur when several users or processes load and/or attempt to modify the same records at the same time. Record locking is a methodology used in relational databases to avoid inconsistent updates to data.
Like many other programming languages, 4D provides the ability to iterate over numbers with a For(…) / End for statement, or over a condition thanks to the While(…)/End while and Repeat/Until(…) keywords. These iterations (or loops) are very useful, but not the most appropriate way to iterate over advanced data types such as collections and entity selections. That’s why the new For each(…)/End for each iterator has been created, to help ease your coding!
4D v17 includes dynamic forms, initially introduced in 4D v16 R6, a powerful and flexible way to dynamically build forms fully adapted to your end users’ needs. The possibilities of dynamic forms are tremendous. In this post, we’ll see a concrete example of what you can do with these new forms.
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