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Check if value contains another: contains

The contains template function checks whether one value is found inside another. It works with strings (substring search), lists (membership check), and dictionaries (key lookup). It uses Python’s in operator under the hood.

This is useful when you need to check if a sensorSensors return information about a thing, for instance the level of water in a tank. [Learn more] value includes a specific word, if a list of items includes a particular entry, or if a dictionary has a certain key. For example, you might want to check if a weather condition string contains “rain”, if a list of active devicesA device is a model representing a physical or logical unit that contains entities. includes a specific one, or filter 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] whose states contain a particular substring.

Usage

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

As a filter

As a test

Template

{{ "hello world" | contains("world") }}

Result (boolean)

true

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.

How to read a signature

Here is the signature of the round filter as an example:

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

round is the name of the function.
Between the parentheses are the parameters. Each parameter has a name, followed by a colon and the type of value the parameter expects. The type only tells you what kind of value to pass. For default: Any, you pass a value of any type, such as 0 or "unknown", not the word Any.
= 0 and = "common" are default values. You can leave out precision and method, and round uses these default values.
default has no =, but the parameter list marks default as optional. If you leave out default and round gets a value that isn’t a number, round raises an error.
-> shows the type of value the function returns.
Inside a signature, | means “or”. This function returns a decimal number, a whole number, or the value you passed as default.

round is a filter, so the first parameter, value, is the value before the |. For example, {{ 3.14159 | round(2) }} returns 3.14.

The types you’ll see most often:

str: text, such as "hello"
int: a whole number, such as 5
float: a decimal number, such as 3.14
bool: true or false
list: a list of values, such as [1, 2, 3]. list[str] is a list of texts.
dict: a set of keys and values, such as {"name": "Kitchen"}
datetime and timedelta: a date and time, and a duration. For details, refer to Dates and times.
None: no value
Any: any type of value

Some signatures use special forms:

*args means you can pass any number of values, separated by commas. For example, average(1, 2, 3).
value | name(...) means the function is a filter. The value before the | is passed to the filter as its first parameter. Some filter signatures, like the round example, show this value as the first parameter between the parentheses instead.

contains(
    value: str | list | dict,
    item: Any,
) -> bool

Function parameters

The following parameters can be provided to this function.

value any Required

The value to search in. Can be a string (checks for substring), a list (checks for membership), or a dictionary (checks for key).

item any Required

The value to search for within the first value.

Different container types

The contains function adapts to the type of value being searched.

Template: Works with strings, lists, and dicts

String: {{ "automation running" | contains("running") }}
List: {{ [1, 2, 3] | contains(2) }}
Dict: {{ {"name": "test"} | contains("name") }}

Result (string)

String: true
List: true
Dict: true

Using as a test with select

Use contains as a test to filter lists of values.

Template: Filter strings containing "rain"

{{
  ["sunny", "rainy day", "cloudy", "light rain"]
  | select("contains", "rain") | list
}}

Result (list)

['rainy day', 'light rain']

Good to know

On dictionaries, this checks keys, not values. Use value in my_dict.values() when you need to match a value.
String matching is case-sensitive. Pipe through | lower first to make it case-insensitive.
Unlike in as a test, the argument order here is container first, item second.

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.

Check if a weather condition includes rain

Test the weather state to decide whether to send a reminder to bring an umbrella.

Template

{% if states("weather.home") | contains("rain") %}
  Don't forget your umbrella!
{% else %}
  No rain expected
{% endif %}

Result (string)

Don't forget your umbrella!

Filter entities by state content

Find all sensors whose state contains a specific keyword.

Template: Find online items

{{
  ["online", "offline", "online - active", "standby"]
  | select("contains", "online") | list
}}

Result (list)

['online', 'online - active']

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.

Tip

AI assistants like ChatGPT or Claude can also explain or fix templates when you describe what you want in plain language.

Related template functions

These functions work well alongside this one:

Check if entity has a value: has_value - Tests if an entity exists and has a valid state (not unavailable or unknown).
Immediate if (ternary): iif - Shorthand for basic if/else logic in a single expression.

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