Store a table
In the previous examples, the tables were only for use in the current context of the Data table or the Dropdown control. Often in your app, you'll need to store those tables and use them in multiple places within the app. To do this, Power Apps has a table variable called a collection.
Collections are a type of variable in Power Apps
Collections are table variables in which you can store data in a structured format, as you would in a tabular data source, without writing to a data source. In other words, they store values in rows and columns. You can use collections with table functions as you would any other data source. However, you can't use a collection with the Form control. If you have a developer background, you can think of a collection as an array. You don't have to initialize or predefine a collection. When you create it and set values, Power Apps sets it up for you.
Create a collection
Creating a collection can be done within your app anywhere an action can normally be taken. For example, you can create a collection when pressing a button by changing the OnSelect property of the button, or even create a collection whenever you come to a certain screen by changing the OnVisible property of that screen. You can create a collection named collectMyFirstCollection by using this formula.
Collect(collectMyFirstCollection, {Name: "Shane", FavoriteColor:"Orange"})
The collection would have a column named Name and another column named FavoriteColor. The collection would have one record (row) of data with Shane as the value of Name and Orange as the value for FavoriteColor. Notice the syntax is similar to the Table function from earlier in this module.
You could add another record to the collection by using this formula.
Collect(collectMyFirstCollection, {Name: "Nicola", FavoriteColor:"Purple"})
You can also add more than one record at a time by using this formula.
Collect(collectMyFirstCollection, {Name: "Jeff", FavoriteColor:"Blue"}, {Name: "Chewy", FavoriteColor: "Red"})
If you ran all those commands, your collection would look like this table:
| Name | FavoriteColor |
|---|---|
| Shane | Orange |
| Nicola | Purple |
| Jeff | Blue |
| Chewy | Red |
You could then use that collection as a data source for your Gallery or Drop-down control.
Remove data from your collection
To clear out the existing data from your collection before you add data, you can use the ClearCollect function. If you take the existing collection from the previous example, you can use this formula:
ClearCollect(collectMyFirstCollection, {Name: "Fausto", FavoriteColor:"Green"})
Now your collection would look like this table:
| Name | FavoriteColor |
|---|---|
| Fausto | Green |
You can also remove all the records from a collection by using the Clear function. This formula removes all the records from your collection but leaves your columns intact:
Clear(collectMyFirstCollection)