Template Conditions in Rules

Use JavaScript or Jinja2 templates for dynamic rule conditions Write powerful, flexible conditions using JavaScript expressions or Home Assistant templates.

Overview
JavaScript Conditions
Jinja2 Conditions
Choosing Between JavaScript and Jinja2
Complete Examples
Best Practices
Troubleshooting

Overview

LCARdS supports two types of template conditions in rules:

JavaScript - Using [[[ ]]] syntax with direct access to Home Assistant states
Jinja2 - Using {{ }} syntax with Home Assistant's template engine

Both types evaluate to boolean (true/false) and work seamlessly with the rules engine.

When to Use Templates

Use template conditions when you need:

✅ Complex logic (multiple entities, calculations)
✅ Numeric comparisons with formulas
✅ String manipulation or pattern matching
✅ Time-based calculations
✅ Attribute access from entities

Use simple entity conditions when:

✅ Checking a single entity state
✅ Simple above/below thresholds
✅ Basic time ranges

JavaScript Conditions

JavaScript conditions use the [[[ ]]] syntax and have direct access to Home Assistant's state object.

Syntax

yaml

rules:
  - id: example_js_rule
    when:
      any:
        - condition: "[[[return states['light.bedroom'].state === 'on']]]"
    apply:
      # ... your styling

Important:

Must be wrapped in [[[ ]]] (triple brackets)
Must include return statement
Expression must evaluate to boolean

Available Context

Inside JavaScript conditions, you have access to:

Object	Description	Example
`states`	All entity states object	`states['light.bedroom']`
`hass`	Full Home Assistant object	`hass.states['sensor.temp']`
`entity`	Current entity (if rule has entity)	`entity.state`

Accessing Entity States

javascript

// Get entity state
states['light.bedroom'].state  // 'on' or 'off'

// Get entity attributes
states['climate.living_room'].attributes.temperature  // 72.5

// Get entity last_changed
states['sensor.motion'].last_changed  // timestamp

// Check if entity exists
states['sensor.temp'] !== undefined

Examples

Simple State Check

yaml

rules:
  - id: light_on
    when:
      any:
        - condition: "[[[return states['light.bedroom'].state === 'on']]]"

Numeric Comparison

yaml

rules:
  - id: temp_high
    when:
      any:
        - condition: "[[[return parseFloat(states['sensor.temperature'].state) > 25]]]"

Multiple Entities (AND)

yaml

rules:
  - id: both_lights_on
    when:
      any:
        - condition: |
            [[[
              return states['light.bedroom'].state === 'on' &&
                     states['light.bathroom'].state === 'on'
            ]]]

Multiple Entities (OR)

yaml

rules:
  - id: any_light_on
    when:
      any:
        - condition: |
            [[[
              return states['light.bedroom'].state === 'on' ||
                     states['light.bathroom'].state === 'on' ||
                     states['light.kitchen'].state === 'on'
            ]]]

Attribute Access

yaml

rules:
  - id: hvac_cooling
    when:
      any:
        - condition: "[[[return states['climate.house'].attributes.hvac_action === 'cooling']]]"

Battery Level Check

yaml

rules:
  - id: low_battery
    when:
      any:
        - condition: "[[[return states['sensor.phone_battery'].attributes.battery_level < 20]]]"

Time-Based with Calculation

yaml

rules:
  - id: working_hours
    when:
      any:
        - condition: |
            [[[
              const hour = new Date().getHours();
              return hour >= 9 && hour < 17;
            ]]]

Complex Multi-Condition

yaml

rules:
  - id: comfort_check
    when:
      any:
        - condition: |
            [[[
              const temp = parseFloat(states['sensor.temperature'].state);
              const humidity = parseFloat(states['sensor.humidity'].state);
              const hvacOn = states['climate.ac'].state !== 'off';

              return (temp > 25 || humidity > 60) && !hvacOn;
            ]]]

Jinja2 Conditions

Jinja2 conditions use Home Assistant's native template engine with {{ }} syntax.

Syntax

yaml

rules:
  - id: example_jinja_rule
    when:
      any:
        - condition: "{{ states('light.bedroom') == 'on' }}"
    apply:
      # ... your styling

Important:

Must be wrapped in {{ }} (double curly braces)
Must be quoted in YAML (use double or single quotes)
Expression must evaluate to boolean (true/false)

Home Assistant Functions

Function	Description	Example
`states('entity_id')`	Get entity state	`states('light.bedroom')`
`state_attr('entity', 'attr')`	Get attribute	`state_attr('climate.ac', 'temperature')`
`is_state('entity', 'state')`	Check state equality	`is_state('light.bedroom', 'on')`
`has_value('entity')`	Check if entity has value	`has_value('sensor.temp')`

Jinja2 Filters

Filter	Description	Example
`\| float`	Convert to number	`states('sensor.temp') \| float`
`\| int`	Convert to integer	`states('sensor.count') \| int`
`\| round(n)`	Round to n decimals	`states('sensor.temp') \| float \| round(1)`
`\| upper`	Uppercase	`states('sensor.mode') \| upper`
`\| lower`	Lowercase	`states('sensor.mode') \| lower`

Examples

Simple State Check

yaml

rules:
  - id: light_on
    when:
      any:
        - condition: "{{ states('light.bedroom') == 'on' }}"

Numeric Comparison

yaml

rules:
  - id: temp_high
    when:
      any:
        - condition: "{{ states('sensor.temperature') | float > 25 }}"

Multiple Entities (AND)

yaml

rules:
  - id: both_lights_on
    when:
      any:
        - condition: "{{ states('light.bedroom') == 'on' and states('light.bathroom') == 'on' }}"

Multiple Entities (OR)

yaml

rules:
  - id: any_light_on
    when:
      any:
        - condition: "{{ states('light.bedroom') == 'on' or states('light.bathroom') == 'on' or states('light.kitchen') == 'on' }}"

Attribute Access

yaml

rules:
  - id: hvac_cooling
    when:
      any:
        - condition: "{{ state_attr('climate.house', 'hvac_action') == 'cooling' }}"

Battery Level Check

yaml

rules:
  - id: low_battery
    when:
      any:
        - condition: "{{ state_attr('sensor.phone_battery', 'battery_level') | int < 20 }}"

Using is_state Helper

yaml

rules:
  - id: door_open
    when:
      any:
        - condition: "{{ is_state('binary_sensor.front_door', 'on') }}"

Complex Multi-Condition

yaml

rules:
  - id: comfort_check
    when:
      any:
        - condition: "{{ (states('sensor.temperature') | float > 25 or states('sensor.humidity') | float > 60) and not is_state('climate.ac', 'cool') }}"

Choosing Between JavaScript and Jinja2

Use JavaScript When:

✅ You prefer JavaScript syntax

More familiar with JavaScript than Jinja2
Want to use modern ES6+ features
Need complex multi-line logic

✅ You need local calculations

Time zone handling (new Date())
Math operations
String manipulation with JS methods

✅ You want IDE support

Better autocomplete in most editors
Syntax highlighting for JavaScript

Use Jinja2 When:

✅ You prefer Home Assistant templates

Already use Jinja2 in HA automations
Familiar with HA template functions
Want consistency with HA config

✅ You need HA-specific functions

is_state(), state_attr() helpers
HA template filters
Time-based HA functions

✅ Shorter, simpler expressions

One-line comparisons
Basic state checks
Simple numeric comparisons

Performance

Both JavaScript and Jinja2 have similar performance:

JavaScript: ~0.01-0.1ms per evaluation
Jinja2: ~0.1-0.5ms per evaluation (includes HA call)

Recommendation: Choose based on preference, not performance.

Complete Examples

Example 1: Temperature Monitoring (Both Syntaxes)

JavaScript Version

yaml

rules:
  # Critical temperature
  - id: temp_critical_js
    priority: 100
    when:
      any:
        - condition: "[[[return parseFloat(states['sensor.temperature'].state) > 35]]]"
    apply:
      overlays:
        temp_display:
          style:
            color: var(--lcars-red)
            glow_size: 8

  # Normal temperature
  - id: temp_normal_js
    priority: 10
    when:
      any:
        - condition: "[[[return parseFloat(states['sensor.temperature'].state) <= 25]]]"
    apply:
      overlays:
        temp_display:
          style:
            color: var(--lcars-blue)

Jinja2 Version

yaml

rules:
  # Critical temperature
  - id: temp_critical_jinja
    priority: 100
    when:
      any:
        - condition: "{{ states('sensor.temperature') | float > 35 }}"
    apply:
      overlays:
        temp_display:
          style:
            color: var(--lcars-red)
            glow_size: 8

  # Normal temperature
  - id: temp_normal_jinja
    priority: 10
    when:
      any:
        - condition: "{{ states('sensor.temperature') | float <= 25 }}"
    apply:
      overlays:
        temp_display:
          style:
            color: var(--lcars-blue)

Example 2: Multi-Sensor Alert (JavaScript)

yaml

rules:
  - id: climate_alert
    when:
      any:
        - condition: |
            [[[
              const temp = parseFloat(states['sensor.temperature'].state);
              const humidity = parseFloat(states['sensor.humidity'].state);
              const motion = states['binary_sensor.motion'].state === 'on';
              const acOn = states['climate.ac'].state !== 'off';

              // Alert if: (hot OR humid) AND motion detected AND AC not running
              return (temp > 27 || humidity > 65) && motion && !acOn;
            ]]]
    apply:
      base_svg:
        filter_preset: red-alert
      overlays:
        alert_text:
          style:
            color: var(--lcars-red)
            font_size: 36
            glow_size: 12

Example 3: Time-Based Modes (Jinja2)

yaml

rules:
  # Morning mode (6am-12pm)
  - id: morning_mode
    priority: 100
    when:
      all:
        - entity: sensor.time  # Updates every minute
          state_available: true
        - condition: "{{ now().hour >= 6 and now().hour < 12 }}"
    apply:
      base_svg:
        filter_preset: subtle
      overlays:
        mode_text:
          content: "Good Morning"
          style:
            color: var(--lcars-orange)

  # Evening mode (6pm-11pm)
  - id: evening_mode
    priority: 90
    when:
      all:
        - entity: sensor.time
          state_available: true
        - condition: "{{ now().hour >= 18 and now().hour < 23 }}"
    apply:
      base_svg:
        filter_preset: dimmed
      overlays:
        mode_text:
          content: "Good Evening"
          style:
            color: var(--lcars-blue)

Best Practices

1. Use YAML Pipe for Multi-Line JavaScript

yaml

# ✅ Good - Readable multi-line
- condition: |
    [[[
      const temp = parseFloat(states['sensor.temperature'].state);
      return temp > 25 && temp < 30;
    ]]]

# ❌ Bad - Hard to read
- condition: "[[[const temp = parseFloat(states['sensor.temperature'].state); return temp > 25 && temp < 30;]]]"

2. Always Return Boolean

yaml

# ✅ Good - Explicit boolean
- condition: "[[[return states['light.bedroom'].state === 'on']]]"

# ❌ Bad - Truthy but not boolean
- condition: "[[[return states['light.bedroom'].state]]]"

3. Handle Missing Entities

yaml

# ✅ Good - Check entity exists
- condition: |
    [[[
      const sensor = states['sensor.temperature'];
      if (!sensor) return false;
      return parseFloat(sensor.state) > 25;
    ]]]

# ❌ Bad - Will error if sensor doesn't exist
- condition: "[[[return parseFloat(states['sensor.temperature'].state) > 25]]]"

4. Use parseFloat for Numeric States

yaml

# ✅ Good - Convert to number
- condition: "[[[return parseFloat(states['sensor.temp'].state) > 25]]]"

# ❌ Bad - String comparison
- condition: "[[[return states['sensor.temp'].state > 25]]]"  # "30" > 25 might not work as expected

5. Quote Jinja2 Templates in YAML

yaml

# ✅ Good - Quoted
- condition: "{{ states('light.bedroom') == 'on' }}"

# ❌ Bad - Not quoted (YAML parsing error)
- condition: {{ states('light.bedroom') == 'on' }}

6. Use entity Parameter When Available

For rules that already have an entity, you can use the entity context:

yaml

rules:
  - id: light_state_check
    when:
      all:
        - entity: light.bedroom  # This is available as 'entity' in JS
          state_available: true
        - condition: "[[[return entity.state === 'on']]]"  # Use 'entity' instead of states lookup

Troubleshooting

JavaScript Conditions

Error: "SyntaxError: Unexpected token"

Problem: Invalid JavaScript syntax

yaml

# ❌ Wrong
- condition: "[[[return states['light.bedroom'].state = 'on']]]"  # Single = is assignment

# ✅ Correct
- condition: "[[[return states['light.bedroom'].state === 'on']]]"  # Triple === for equality

Error: "Cannot read property 'state' of undefined"

Problem: Entity doesn't exist

yaml

# ❌ Wrong - No null check
- condition: "[[[return states['sensor.missing'].state === 'on']]]"

# ✅ Correct - Check existence
- condition: |
    [[[
      const sensor = states['sensor.missing'];
      return sensor && sensor.state === 'on';
    ]]]

Condition Always False

Problem: String comparison instead of numeric

yaml

# ❌ Wrong - "25" as string
- condition: "[[[return states['sensor.temp'].state > 20]]]"  # Might compare strings

# ✅ Correct - Convert to number
- condition: "[[[return parseFloat(states['sensor.temp'].state) > 20]]]"

Jinja2 Conditions

Error: "TemplateError: Must be quoted"

Problem: Jinja2 template not quoted in YAML

yaml

# ❌ Wrong
- condition: {{ states('light.bedroom') == 'on' }}

# ✅ Correct
- condition: "{{ states('light.bedroom') == 'on' }}"

Condition Not Updating

Problem: Missing entity trigger

For time-based Jinja2 conditions, add sensor.time:

yaml

# ❌ Wrong - Won't update
when:
  any:
    - condition: "{{ now().hour >= 18 }}"

# ✅ Correct - Includes trigger
when:
  all:
    - entity: sensor.time  # Triggers every minute
      state_available: true
    - condition: "{{ now().hour >= 18 }}"

Error: "Result is not boolean"

Problem: Jinja2 returns string instead of boolean

yaml

# ❌ Wrong - Returns 'True' as string
- condition: "{{ states('light.bedroom') }}"

# ✅ Correct - Explicit comparison
- condition: "{{ states('light.bedroom') == 'on' }}"

General Issues

Rule Not Triggering

Check logs - Enable debug mode to see rule evaluation:
javascript
```
window.lcards.debug.rules.enable()
```
Verify entity exists - Check entity ID in Developer Tools → States
Test condition separately - Test JavaScript/Jinja2 in browser console or HA Templates
Check priority - Higher priority rules might be stopping evaluation

Rule Applying Wrong Values

Check rule order - Multiple matching rules apply in priority order
Use stop: true - Stop lower-priority rules from overriding
Test incrementally - Comment out other rules to isolate issue

Rules Configuration - Complete rules engine documentation
JavaScript Quick Start - JavaScript examples
Jinja2 Examples - Jinja2 test cases
Rules Engine Architecture - Technical implementation

← Back to Configuration | Rules Guide

Filter	Description	Example
`\| float`	Convert to number	`states('sensor.temp') \| float`
`\| int`	Convert to integer	`states('sensor.count') \| int`
`\| round(n)`	Round to n decimals	`states('sensor.temp') \| float \| round(1)`
`\| upper`	Uppercase	`states('sensor.mode') \| upper`
`\| lower`	Lowercase	`states('sensor.mode') \| lower`

Template Conditions in Rules ​

Table of Contents ​

Overview ​

When to Use Templates ​

JavaScript Conditions ​

Syntax ​

Available Context ​

Accessing Entity States ​

Examples ​

Simple State Check ​

Numeric Comparison ​

Multiple Entities (AND) ​

Multiple Entities (OR) ​

Attribute Access ​

Battery Level Check ​

Time-Based with Calculation ​

Complex Multi-Condition ​

Jinja2 Conditions ​

Syntax ​

Home Assistant Functions ​

Jinja2 Filters ​

Examples ​

Simple State Check ​

Numeric Comparison ​

Multiple Entities (AND) ​

Multiple Entities (OR) ​

Attribute Access ​

Battery Level Check ​

Using is_state Helper ​

Complex Multi-Condition ​

Choosing Between JavaScript and Jinja2 ​

Use JavaScript When: ​

Use Jinja2 When: ​

Performance ​

Complete Examples ​

Example 1: Temperature Monitoring (Both Syntaxes) ​

JavaScript Version ​

Jinja2 Version ​

Example 2: Multi-Sensor Alert (JavaScript) ​

Example 3: Time-Based Modes (Jinja2) ​

Best Practices ​

1. Use YAML Pipe for Multi-Line JavaScript ​

2. Always Return Boolean ​

3. Handle Missing Entities ​

4. Use parseFloat for Numeric States ​

5. Quote Jinja2 Templates in YAML ​

6. Use entity Parameter When Available ​

Troubleshooting ​

JavaScript Conditions ​

Error: "SyntaxError: Unexpected token" ​

Error: "Cannot read property 'state' of undefined" ​

Condition Always False ​

Jinja2 Conditions ​

Error: "TemplateError: Must be quoted" ​

Condition Not Updating ​

Error: "Result is not boolean" ​

General Issues ​

Rule Not Triggering ​

Rule Applying Wrong Values ​

Related Documentation ​

Template Conditions in Rules

Table of Contents

Overview

When to Use Templates

JavaScript Conditions

Syntax

Available Context

Accessing Entity States

Examples

Simple State Check

Numeric Comparison

Multiple Entities (AND)

Multiple Entities (OR)

Attribute Access

Battery Level Check

Time-Based with Calculation

Complex Multi-Condition

Jinja2 Conditions

Syntax

Home Assistant Functions

Jinja2 Filters

Examples

Simple State Check

Numeric Comparison

Multiple Entities (AND)

Multiple Entities (OR)

Attribute Access

Battery Level Check

Using is_state Helper

Complex Multi-Condition

Choosing Between JavaScript and Jinja2

Use JavaScript When:

Use Jinja2 When:

Performance

Complete Examples

Example 1: Temperature Monitoring (Both Syntaxes)

JavaScript Version

Jinja2 Version

Example 2: Multi-Sensor Alert (JavaScript)

Example 3: Time-Based Modes (Jinja2)

Best Practices

1. Use YAML Pipe for Multi-Line JavaScript

2. Always Return Boolean

3. Handle Missing Entities

4. Use parseFloat for Numeric States

5. Quote Jinja2 Templates in YAML

6. Use entity Parameter When Available

Troubleshooting

JavaScript Conditions

Error: "SyntaxError: Unexpected token"

Error: "Cannot read property 'state' of undefined"

Condition Always False

Jinja2 Conditions

Error: "TemplateError: Must be quoted"

Condition Not Updating

Error: "Result is not boolean"

General Issues

Rule Not Triggering

Rule Applying Wrong Values

Related Documentation