Power-Apps-Canvas-Yaml

# Power Apps Canvas Apps YAML Structure Guide

Overview

This document provides comprehensive instructions for working with YAML code for Power Apps canvas apps based on the official Microsoft Power Apps YAML schema (v3.0) and Power Fx documentation.

**Official Schema Source**: https://raw.githubusercontent.com/microsoft/PowerApps-Tooling/refs/heads/master/schemas/pa-yaml/v3.0/pa.schema.yaml

Power Fx Design Principles

Power Fx is the formula language used throughout Power Apps canvas apps. It follows these core principles:

Design Principles

- **Simple**: Uses familiar concepts from Excel formulas

- **Excel Consistency**: Aligns with Excel formula syntax and behavior

- **Declarative**: Describes what you want, not how to achieve it

- **Functional**: Avoids side effects; most functions are pure

- **Composition**: Complex logic built by combining simpler functions

- **Strongly Typed**: Type system ensures data integrity

- **Integrated**: Works seamlessly across the Power Platform

Language Philosophy

Power Fx promotes:

- Low-code development through familiar Excel-like formulas

- Automatic recalculation when dependencies change

- Type safety with compile-time checking

- Functional programming patterns

Root Structure

Every Power Apps YAML file follows this top-level structure:

App:
  Properties:
    # App-level properties and formulas
    StartScreen: =Screen1

Screens:
  # Screen definitions

ComponentDefinitions:
  # Custom component definitions

DataSources:
  # Data source configurations

EditorState:
  # Editor metadata (screen order, etc.)

1. App Section

The `App` section defines application-level properties and configuration.

App:
  Properties:
    StartScreen: =Screen1
    BackEnabled: =false
    # Other app properties with Power Fx formulas

Key Points:

- Contains application-wide settings

- Properties use Power Fx formulas (prefixed with `=`)

- `StartScreen` property is commonly specified

2. Screens Section

Defines all screens in the application as an unordered map.

Screens:
  Screen1:
    Properties:
      # Screen properties
    Children:
      - Label1:
          Control: Label
          Properties:
            Text: ="Hello World"
            X: =10
            Y: =10
      - Button1:
          Control: Button
          Properties:
            Text: ="Click Me"
            X: =10
            Y: =100

Screen Structure:

- **Properties**: Screen-level properties and formulas

- **Children**: Array of controls on the screen (ordered by z-index)

Control Definition Format:

ControlName:
  Control: ControlType      # Required: Control type identifier
  Properties:
    PropertyName: =PowerFxFormula
  # Optional properties:
  Group: GroupName          # For organizing controls in Studio
  Variant: VariantName      # Control variant (affects default properties)
  MetadataKey: Key          # Metadata identifier for control
  Layout: LayoutName        # Layout configuration
  IsLocked: true/false      # Whether control is locked in editor
  Children: []              # For container controls (ordered by z-index)

Control Versioning:

You can specify control versions using the `@` operator:

MyButton:
  Control: Button@2.1.0     # Specific version
  Properties:
    Text: ="Click Me"

MyLabel:
  Control: Label            # Uses latest version by default
  Properties:
    Text: ="Hello World"

3. Control Types

Standard Controls

Common first-party controls include:

- **Basic Controls**: `Label`, `Button`, `TextInput`, `HTMLText`

- **Input Controls**: `Slider`, `Toggle`, `Checkbox`, `Radio`, `Dropdown`, `Combobox`, `DatePicker`, `ListBox`

- **Display Controls**: `Image`, `Icon`, `Video`, `Audio`, `PDF viewer`, `Barcode scanner`

- **Layout Controls**: `Container`, `Rectangle`, `Circle`, `Gallery`, `DataTable`, `Form`

- **Chart Controls**: `Column chart`, `Line chart`, `Pie chart`

- **Advanced Controls**: `Timer`, `Camera`, `M