Merge action responses: merge_response

The merge_response template function takes the response dictionary from a multi-entity action call and merges it into a single flat list. When you call an action that targets multiple entitiesAn entity represents a sensor, actor, or function in Home Assistant. Entities are used to monitor physical properties or to control other entities. An entity is usually part of a device or a service. [Learn more], the response is a dictionary keyed by entity ID, where each value contains the entity’s response data. merge_response flattens this structure into a single list. It adds the entity_id to each item for reference. For responses with a list, such as calendar events, it also adds a value_key with the name of that list.

This is useful when you call actions like calendar.get_events or weather.get_forecasts that target multiple entities at once. Without merge_response, you would need to manually loop through the response dictionary and extract items from each entity. This function handles that for you and produces a unified list that is straightforward to sort, filter, and display. Each item in the result includes an entity_id field so you can still tell which entity it came from.

Usage

Here’s how to use this template function. Copy any example and adjust it to your setup.

{{ merge_response(response) }}

[
  {
    "start": "2024-03-15",
    "summary": "Meeting",
    "entity_id": "calendar.work",
    "value_key": "events",
  },
  {
    "start": "2024-03-15",
    "summary": "Dentist",
    "entity_id": "calendar.personal",
    "value_key": "events",
  },
]

Function signature

The signature is a technical summary of this template function. It shows the name of the function, the values (called parameters) it accepts, and what type of data each parameter expects (for example, a piece of text or a number).

Function parameters that have a = with a value after them are optional. If you leave them out, the default value shown is used automatically.

Function parameters without a = are usually required. A few optional parameters have no default value, so the signature shows them without a = as well. To check whether a parameter is required, look at the parameter list below the signature. Each parameter is marked as Required or Optional.

The most common optional parameter without a default value is default. The default parameter sets the value a function returns when the function can’t produce a result, for example, when float gets text that isn’t a number. If you leave out default, there is no fallback value, so most functions raise an error and the template fails. The parameter list of each function says what happens. If you set default, the function returns your value instead.

round(
    value: Any,
    precision: int = 0,
    method: str = "common",
    default: Any,
) -> float | int | Any

merge_response(
    value: dict,
) -> list

Function parameters

The following parameters can be provided to this function.

Good to know

• Adds an entity_id field to each item, so you can tell which entity each response came from after merging.
• Some responses have exactly one key that holds a list, such as events. In that case, the items of all these lists are combined into one list. Each item also gets a value_key field with the name of that key, such as events.
• Other response dictionaries work too, for example, with several keys. Each entity’s response then becomes one item in the list.
• The result isn’t sorted. If the order matters, use sort.
• An empty response returns an empty list ([]).

Try it yourself

Ready to test this? Open Settings > Tools > Template, paste the example into the Template editor, and watch the result update on the right. Edit the values to see how the function adapts to your own entitiesAn entity represents a sensor, actor, or function in Home Assistant. Entities are used to monitor physical properties or to control other entities. An entity is usually part of a device or a service. [Learn more].

More examples

Real scenarios where this function comes up in automations and templates. Copy any example and adapt it to your setup.

Merge calendar events from multiple calendars

Call calendar.get_events targeting multiple calendars and merge all events into a single sorted list.

action:
  - action: calendar.get_events
    target:
      entity_id:
        - calendar.work
        - calendar.personal
    data:
      duration:
        hours: 24
    response_variable: agenda
  - action: notify.mobile
    data:
      message: >
        Today's events:
        {% for event in merge_response(agenda) | sort(attribute="start") %}
        - {{ event.summary }} ({{ event.entity_id.split(".")[1] }})
        {% endfor %}

Merge weather forecasts

Combine forecasts from multiple weather entities into one list for comparison.

action:
  - action: weather.get_forecasts
    target:
      entity_id:
        - weather.home
        - weather.office
    data:
      type: daily
    response_variable: forecasts
  - action: notify.mobile
    data:
      message: >
        {% for item in merge_response(forecasts) %}
        {{ item.entity_id }}: {{ item.temperature }}C
        {% endfor %}

Still stuck?

The Home Assistant community is quick to help: join Discord for real-time chat, post on the community forum with your template and expected result, or share on our subreddit /r/homeassistant.

Related template functions

These functions work well alongside this one:

• Merge dictionaries: combine - Merges multiple dictionaries into one.

• Serialize to JSON: to_json - Serializes a value to a JSON string.

• Parse JSON string: from_json - Parses a JSON string into a Python object.

• Flatten nested lists: flatten - Flattens nested lists into a single flat list.