powerapps-variables-context-variables-and-collections

PowerApps: Variables and Context Variables

PowerApps provides different types of variables to store and manipulate data at different levels of scope within your app. The primary types of variables are:

Global Variables
Context Variables
Collections

In this document, we'll focus on Global Variables Context Variables and Collections.

1. Global Variables

Description

Global variables are available throughout the app and can be accessed from any screen or component.

🛠 Syntax

Set(variableName, value);

variableName: The name of the global variable
value: The value you want to assign to it

Example: Set a Global Variable

Set(userName, "John Doe");

This sets the global variable userName to "John Doe".

Example: Use a Global Variable

Label1.Text = userName;

Displays the value of userName in a label.

✅ When to Use

When you need to share data across multiple screens
For user settings, session data, or app-wide status

2. Context Variables

Description

Context variables are local to a specific screen. They're useful when you need temporary state or screen-level configuration.

🛠 Syntax

UpdateContext({ variableName: value });

Wrap the variable and value in curly braces {} as it's a record.

Example: Set a Context Variable

UpdateContext({ counter: 1 });

This sets the counter context variable to 1.

Example: Use a Context Variable

Label1.Text = counter;

Displays the value of counter on the screen.

Example: Update Context Variable on Button Click

UpdateContext({ counter: counter + 1 });

Increments the counter each time the button is clicked.

✅ When to Use

For temporary or screen-specific values
For modal dialogs or visibility toggles
For passing data during screen navigation

Navigating with Context Variables

You can also pass context variables during navigation using the Navigate function.

Example: Navigate and Pass Context

Navigate(Screen2, ScreenTransition.Fade, { productId: 123 });

Navigates to Screen2 and passes productId as a context variable.

In Screen2, you can directly use:

Label.Text = productId;

Key Differences: Global vs Context Variables

Feature	Global Variables	Context Variables
Scope	App-wide	Screen-level
Created with	`Set()`	`UpdateContext()`
Persistence	Until app is closed	Until user leaves screen
Usage	Shared state, user data	Temporary UI state

Best Practices

Use Context Variables for screen logic and temporary state.
Use Global Variables for data that needs to persist across screens.
Use descriptive names to avoid confusion.
Clear variables when no longer needed:

Set(userName, Blank()); // Global
UpdateContext({ counter: Blank() }); // Context

Pro Tip: Debugging Variables

To debug variable values:

Use a Label to display variable contents:

Label.Text = Text(counter);

Use the Variables pane in the PowerApps editor: - Click Variables in the side panel - View Global and Context variables by screen

PowerApps Collections Guide

📘 What is a Collection in PowerApps?

A Collection in PowerApps is a temporary in-memory data table that can be used to store and manipulate data locally in an app. Unlike data from connectors (e.g., SharePoint, SQL), collections are not persisted after the app closes.

Why Use Collections?

Store user input temporarily
Group and manipulate data before saving to a data source
Offline data handling
Preload data for faster access

How to Create a Collection

Syntax

ClearCollect(CollectionName, DataSource or Records)

ClearCollect creates a collection (if it doesn't exist) or clears and re-creates it.
Collect adds new records without clearing.

Example 1: Create a Static Collection

ClearCollect(
  FruitCollection,
  { Name: "Apple", Color: "Red" },
  { Name: "Banana", Color: "Yellow" },
  { Name: "Grape", Color: "Purple" }
);

Creates a collection with fruit data.

Example 2: Create a Collection from a Data Source

ClearCollect(EmployeesCollection, Filter(Employees, (Department = "HR")));

Pulls filtered data from a data source into a local collection.

Example 3: Add a Record to an Existing Collection

Collect(FruitCollection, { Name: "Orange", Color: "Orange" });

Adds a record without clearing the existing ones.

Example 4: Remove a Record

Remove(FruitCollection, First(Filter(FruitCollection, (Name = "Banana"))));

Removes the first "Banana" from the collection.

Example 5: Clear a Collection

Clear(FruitCollection);

Removes all records.

Viewing Collection Data

Use the Collections tab in the Variables pane in PowerApps Studio:

Go to File > Variables > Collections
Click on the collection to view its data

🧪 Looping and Manipulating Data

Example: Update a Collection's Field

UpdateIf(FruitCollection, (Name = "Apple"), { Color: "Green" });

Updates the color of Apple to Green.

Saving Collection Data

Collections are not saved unless manually written to a data source:

ForAll(
  FruitCollection,
  Patch(SharePointList, Defaults(SharePointList), { Title: Name, Color: Color })
);

Best Practices

👉 Use collections for temporary or offline storage
👉 Clear and reuse collections to reduce memory usage
👉 Avoid large collections to ensure performance
🚫 Don’t use collections as a replacement for actual data sources

Summary Table

Function	Description
`ClearCollect`	Clears and then creates collection
`Collect`	Adds records to an existing collection
`Clear`	Empties all records
`Remove`	Deletes specific records
`RemoveIf`	Deletes matching records with conditions
`UpdateIf`	Updates specific records
`ForAll`	Loops through collection for operations

Final Example

// Create a collection of tasks
ClearCollect(
  Tasks,
  { Title: "Task 1", Status: "Open" },
  { Title: "Task 2", Status: "In Progress" }
);

// Update a task
UpdateIf(Tasks, (Title = "Task 2"), { Status: "Completed" });

// Remove a task
RemoveIf(Tasks, (Title = "Task 1"));

References

PowerApps Control Properties Guide

Control properties in PowerApps determine how a control looks, behaves, and interacts with users. These properties can be static (set to a fixed value) or dynamic (based on formulas or user interaction).

✳️ Common Control Properties

Property	Description	Example Formula
`Text`	The text shown in the control	`"Welcome!"` or `Concatenate("Hi ", User().FullName)`
`Default`	Initial value of an input control	`"John Doe"` or `LookUp(Users, ID = 1, Name)`
`Visible`	Whether control is visible	`true` or `Slider1.Value > 50`
`DisplayMode`	Whether control is editable, view-only, or disabled	`DisplayMode.Edit`, `DisplayMode.View`
`Fill`	Background color of control	`Color.LightBlue` or `If(Value>10, Red, Green)`
`BorderColor`	Border color	`Color.Black` or `If(IsSelected, Blue, Gray)`
`OnSelect`	Runs a formula when control is clicked/tapped	`Navigate(Screen2)`
`Tooltip`	Shows text when user hovers	`"Click to submit the form"`
`Size`	Font size	`16`
`Color`	Text color	`Color.White` or `If(Condition, Red, Black)`
`Width` / `Height`	Dimensions of the control	`Width = 200`, `Height = 40`

Examples by Control Type

🗾 Label

Properties Used:

Text
Color
Font
Visible

Label1.Text = "Hello, " & User().FullName;
Label1.Color = If(Hour(Now()) > 18, Color.White, Color.Black);
Label1.Visible = Checkbox1.Value;

🔲 Text Input

Properties Used:

Default
HintText
OnChange
BorderColor

TextInput1.Default = "Enter your name";
TextInput1.HintText = "e.g. Jane Doe";
TextInput1.OnChange = Set(UserName, TextInput1.Text);
TextInput1.BorderColor = If(IsBlank(TextInput1.Text), Color.Red, Color.Gray);

🔳 Button

Properties Used:

Text
OnSelect
DisplayMode
Fill

Button1.Text = "Submit";
Button1.OnSelect = SubmitForm(EditForm1);
Button1.DisplayMode = If(
  IsBlank(TextInput1.Text),
  DisplayMode.Disabled,
  DisplayMode.Edit
);
Button1.Fill = If(
  (Button1.DisplayMode = DisplayMode.Disabled),
  Color.Gray,
  Color.Green
);

Properties Used:

Items
Default
OnChange

Dropdown1.Items = ["Low", "Medium", "High"];
Dropdown1.Default = "Medium";
Dropdown1.OnChange = Set(PriorityLevel, Dropdown1.Selected.Value);

✅ Checkbox

Properties Used:

Default
Text
OnCheck / OnUncheck

Checkbox1.Text = "I agree to the terms";
Checkbox1.Default = false;
Checkbox1.OnCheck = UpdateContext({ Agreed: true });
Checkbox1.OnUncheck = UpdateContext({ Agreed: false });

📅 Date Picker

Properties Used:

DefaultDate
MinDate / MaxDate
OnChange

DatePicker1.DefaultDate = Today();
DatePicker1.MinDate = DateAdd(Today(), -30);
DatePicker1.MaxDate = DateAdd(Today(), 30);
DatePicker1.OnChange = Set(SelectedDate, DatePicker1.SelectedDate);

🔀 Dynamic Behavior Example

Disable a submit button until form is complete:

ButtonSubmit.DisplayMode = If(
  IsBlank(TextInput1.Text) || !Checkbox1.Value,
  DisplayMode.Disabled,
  DisplayMode.Edit
);

📌 Tip: Naming Controls

Use meaningful names like txtName, btnSubmit, lblGreeting to improve readability and maintainability.