What you will learn in this guide
How to make data connections between nodes to start creating data driven user interfaces.
All nodes have inputs and outputs. Most of the properties of a node (that you can edit in the property panel) are also available as inputs. Many nodes also have outputs that provide some sort of data value. The most common example is the Text Input node that provides (amonng other things) the typed text as an output value. Using connections you can ensure that an output from one node is written to an input of another node when it is updated. Take a look at the very simple interface below:
Here you have a Text Input and a Text UI Element. Now let's say we want the Text element to show whatever we type into the Text Input. For that we can connect the two nodes.
Now when we type something in the Text Input, it will output that on the Text output. This is connected to the apptly named Text input of the Text node. Now let's test the connection. You need to do this in the Preview Window.
As you can see above, when you start typing in the Text Input you can see the Text is also updated. You can also see in the node graph editor that the connection lights up briefly when data is updated on the output and written to the input.
If you hover the connection in the node graph editor you can also view the latest value that have been sent over the connection, and if you click the little inspection popup you can pin it. Click it again to unpin it.
Making direct connections is fun an all, but using the many utility nodes available you can convert and augment the data on it's way from the output to the final input. Here you can see how we use a String Format node to make a nice greeting.
Now you when you type in the Text Input box you can see how the data is first passed to the String Format node that then augments the data and passes it along on it's Formatted output. Learn more about how the String Format node work in the node reference documentation.
We have covered a very important concept that is used for making data driven reactive user interfaces. But we won't get far just connecting different UI Controls together, most often we need to present data from a database, or an external API. For that we will introduce the data nodes (the green ones), and we'll start with the Variable in the next guide.