Merge dictionaries: combine

The combine template function merges multiple dictionaries into a single dictionary. When the same key appears in more than one dictionary, the value from the last dictionary wins. This lets you build up complex data structures by combining smaller pieces.

This is useful when you need to assemble data from multiple sources into a single dictionary. For example, you might want to combine default settings with overrides, merge attributes from several 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] into one payload, or build up a notification data dictionary from multiple parts. The optional recursive parameter enables deep merging, where nested dictionaries are merged rather than replaced, which is helpful when working with deeply structured data.

Usage

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

{{ combine({"a": 1}, {"b": 2}, {"c": 3}) }}

{'a': 1, 'b': 2, 'c': 3}

{{ {"a": 1} | combine({"b": 2}) }}

{'a': 1, 'b': 2}

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

combine(
    *args: dict,
    recursive: bool = False,
) -> dict

Function parameters

The following parameters can be provided to this function.

Key overlap behavior

When the same key appears in multiple dictionaries, the value from the last dictionary wins.

{{ combine({"color": "red", "size": "large"}, {"color": "blue"}) }}

{'color': 'blue', 'size': 'large'}

Recursive merging

With recursive=true, nested dictionaries are merged together instead of one replacing the other.

{{
  combine(
    {"settings": {"brightness": 100, "color": "warm"}},
    {"settings": {"color": "cool", "mode": "auto"}},
    recursive=true
  )
}}

{'settings': {'brightness': 100, 'color': 'cool', 'mode': 'auto'}}

Good to know

• When the same key appears in multiple dictionaries, the value from the later dictionary wins.
• Without recursive=true, nested dictionaries are replaced outright, not merged.
• The original dictionaries are not modified; a new dictionary is returned.

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.

Build a notification payload

Combine default notification settings with dynamic content.

action:
  - action: notify.mobile
    data: >
      {{
        combine(
          {"title": "Home Assistant", "priority": "normal"},
          {"message": "Front door is " ~ states("binary_sensor.front_door")}
        )
      }}

Merge settings with overrides

Start with default settings and override specific values.

{% set defaults = {"mode": "auto", "brightness": 128, "color_temp": 300} %}
{% set overrides = {"brightness": 255} %}
{{ combine(defaults, overrides) }}

{'mode': 'auto', 'brightness': 255, 'color_temp': 300}

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:

• 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.

• Merge action responses: merge_response - Merges action response dictionaries into a flat list.