Composite functions execute a sequence of different function types, passing data between them. They’re ideal for complex workflows that require multiple steps with different capabilities.
Configuration function : type : composite sequence : - type : function_type_1 # Configuration for first function response_variable : result1 - type : function_type_2 # Configuration for second function (can use {{ result1 }})
List of functions to execute in order. Each can be any function type.
Variable name to store this step’s result for use in subsequent steps
Data Flow Data flows between sequence steps using response_variable:
Step 1 executes
First function runs and produces a result - type : rest resource : https://api.example.com/data response_variable : api_data
Result stored
Result is stored in the variable name specified by response_variable
Step 2 accesses data
Subsequent steps can use the variable in templates - type : template value_template : "Received: {{ api_data.count }} items"
Final result
The last step’s output becomes the function’s final result
Use Cases
Data Processing Fetch raw data and format it for presentation
Multi-step Workflows Execute complex sequences requiring different function types
Service + Template Call services and format their responses
Conditional Logic Use templates to process results conditionally
Best Practices
Use descriptive names for response_variable: response_variable : weather_data # Good response_variable : result # Too generic response_variable : r1 # Not descriptive
Each composite function should accomplish one logical task. If you need many steps, consider breaking into multiple functions. ✅ Good: 2-4 steps for a single purpose ❌ Bad: 10+ steps doing unrelated things
Add error handling in templates: {% if api_data is defined and api_data.success %} {{ api_data.result }} {% else %} Error: Could not fetch data {% endif %}
Test each step individually before combining:
Create individual functions for each step
Verify each works correctly
Combine into composite function
Test the complete sequence
Common Patterns sequence : - type : rest resource : https://api.example.com/data response_variable : raw_data - type : template value_template : "{{ raw_data | format_nicely }}"
sequence : - type : script sequence : - service : domain.service response_variable : service_result - type : template value_template : "{{ service_result.important_field }}"
Pattern 3: Multi-source Aggregation sequence : - type : rest resource : https://api1.example.com response_variable : data1 - type : rest resource : https://api2.example.com response_variable : data2 - type : template value_template : > - Combined data: Source 1: {{ data1.value }} Source 2: {{ data2.value }}
Pattern 4: Scrape + Process sequence : - type : scrape resource : https://example.com response_variable : scraped sensor : - name : price select : ".price" - type : template value_template : > - {% set clean_price = scraped.price | replace('$', '') | float %} Price: ${{ "%.2f" | format(clean_price) }}
Debugging Enable detailed logging:
logger : logs : custom_components.extended_openai_conversation : debug
Logs will show:
Each step’s input parameters
Each step’s output result
Variable assignments
Template rendering
Examples Search and Play Music Search for music, then play the first result:
- spec : name : search_music description : Use this function to search music parameters : type : object properties : query : type : string description : The search query required : - query function : type : composite sequence : - type : script sequence : - service : ytube_music_player.search data : entity_id : media_player.ytube_music_player query : "{{ query }}" - type : template value_template : > - media_content_type,media_content_id,title {% for media in state_attr('sensor.ytube_music_player_extra', 'search') -%} {{media.type}},{{media.id}},{{media.title}} {% endfor%}
Get History with Formatting Combine native get_history with template formatting:
- spec : name : get_history description : Retrieve historical data of specified entities. parameters : type : object properties : entity_ids : type : array items : type : string description : The entity id to filter. start_time : type : string description : Start of the history period in "%Y-%m-%dT%H:%M:%S%z". end_time : type : string description : End of the history period in "%Y-%m-%dT%H:%M:%S%z". required : - entity_ids function : type : composite sequence : - type : native name : get_history response_variable : history_result - type : template value_template : > - {% set ns = namespace(result = [], list = []) %} {% for item_list in history_result %} {% set ns.list = [] %} {% for item in item_list %} {% set last_changed = item.last_changed | as_timestamp | timestamp_local if item.last_changed else None %} {% set new_item = dict(item, last_changed=last_changed) %} {% set ns.list = ns.list + [new_item] %} {% endfor %} {% set ns.result = ns.result + [ns.list] %} {% endfor %} {{ ns.result }}
Fetch and Process External Data Get data from API and format it:
- spec : name : get_weather_detailed description : Get detailed weather information parameters : type : object properties : city : type : string description : City name required : - city function : type : composite sequence : - type : rest resource : "https://wttr.in/{{ city }}?format=j1" response_variable : weather_data - type : template value_template : > - Weather in {{ city }}: Current: {{ weather_data.current_condition[0].temp_C }}°C, {{ weather_data.current_condition[0].weatherDesc[0].value }} Humidity: {{ weather_data.current_condition[0].humidity }}% Wind: {{ weather_data.current_condition[0].windspeedKmph }} km/h 3-Day Forecast: {% for day in weather_data.weather[:3] %} {{ day.date }}: {{ day.mintempC }}-{{ day.maxtempC }}°C {% endfor %}
Next Steps 
