esphome-docs/components/text_sensor/index.rst

Text Sensor Component
=====================

.. seo::
    :description: Instructions for setting up text sensors that represent their state as a string of text.
    :image: folder-open.png

Text sensors are a lot like normal :doc:`sensors </components/sensor/index>`.
But where the "normal" sensors only represent sensors that output **numbers**, this
component can represent any *text*.

.. _config-text_sensor:

Base Text Sensor Configuration
------------------------------

.. code-block:: yaml

    # Example sensor configuration
    name: Livingroom Temperature

    # Optional variables:
    icon: "mdi:water-percent"

Configuration variables:

- **name** (**Required**, string): The name for the sensor.
- **icon** (*Optional*, icon): Manually set the icon to use for the sensor in the frontend.
- **internal** (*Optional*, boolean): Mark this component as internal. Internal components will
  not be exposed to the frontend (like Home Assistant). Only specifying an ``id`` without
  a ``name`` will implicitly set this to true.
- **disabled_by_default** (*Optional*, boolean): If true, then this entity should not be added to any client's frontend,
  (usually Home Assistant) without the user manually enabling it (via the Home Assistant UI).
  Requires Home Assistant 2021.9 or newer. Defaults to ``false``.
- If MQTT enabled, All other options from :ref:`MQTT Component <config-mqtt-component>`.

Automations:

- **on_value** (*Optional*, :ref:`Automation <automation>`): An automation to perform
  when a new value is published. See :ref:`text_sensor-on_value`.
- **on_raw_value** (*Optional*, :ref:`Automation <automation>`): An automation to perform
  when a new value is received that hasn't passed through any filters. See :ref:`text_sensor-on_raw_value`.

.. _text_sensor-filters:

Text Sensor Filters
-------------------

ESPHome allows you to do some basic pre-processing of
text_sensor values before they’re sent to Home Assistant. This is for example
useful if you want to manipulate the text_sensor string in some fashion.

There are a lot of filters that sensors support. You define them by adding a ``filters``
block in the text_sensor configuration (at the same level as ``platform``; or inside each text_sensor block
for platforms with multiple sensors).

Filters are processed in the order they are defined in your configuration.

.. code-block:: yaml

    # Example filters:
    filters:
      - to_upper:
      - to_lower:
      - append: "_prefix"
      - prepend: "suffix_"
      - substitute:
        - "suf -> foo"
        - "pre -> bar"
      - lambda: return {"Hello World"};

``to_upper``
************

Converts all characters within a string to uppercase (only the English alphabet is supported at this time).

.. code-block:: yaml

    # Example configuration entry
    - platform: template
      # ...
      filters:
        - to_upper:

``to_lower``
************

Converts all characters within a string to lowercase (only the English alphabet is supported at this time).

.. code-block:: yaml

    # Example configuration entry
    - platform: template
      # ...
      filters:
        - to_lower:

``append``
**********

Adds a string to the end of the current string.

.. code-block:: yaml

    # Example configuration entry
    - platform: template
      # ...
      filters:
        - append: "_prefix"

``prepend``
***********

Adds a string to the start of the current string.

.. code-block:: yaml

    # Example configuration entry
    - platform: template
      # ...
      filters:
        - prepend: "suffix_"

``substitute``
**************

Search the current value of the text sensor for a string, and replace it with another string.

.. code-block:: yaml

    # Example configuration entry
    - platform: template
      # ...
      filters:
        - substitute:
          - "suf -> foo"
          - "pre -> bar"

The arguments are a list of substitutions, each in the form ``TO_FIND -> REPLACEMENT``.

``lambda``
**********

Perform a advanced operations on the text sensor value. The input string is ``x`` and
the result of the lambda is used as the output (use ``return``).

.. code-block:: yaml

    filters:
      - lambda: |-
          if (x == "Hello") {
            return x + "bar";
          } else {
            return x + "foo";
          }          

Text Sensor Automation
----------------------

You can access the most recent state of the sensor in :ref:`lambdas <config-lambda>` using
``id(sensor_id).state``.

.. _text_sensor-on_value:

``on_value``
************

This automation will be triggered when a new value is published.
In :ref:`Lambdas <config-lambda>` you can get the value from the trigger with ``x``.

.. code-block:: yaml

    text_sensor:
      - platform: version
        # ...
        on_value:
          then:
            - lambda: |-
                ESP_LOGD("main", "The current version is %s", x.c_str());                

Configuration variables: See :ref:`Automation <automation>`.

.. _text_sensor-on_raw_value:

``on_raw_value``
****************

This automation will be triggered when a new value is received that hasn't passed
through any filters. In :ref:`Lambdas <config-lambda>` you can get the value from the trigger with ``x``.

.. code-block:: yaml

    text_sensor:
      - platform: version
        # ...
        on_raw_value:
          then:
            - lambda: |-
                ESP_LOGD("main", "The current version is %s", x.c_str());                

Configuration variables: See :ref:`Automation <automation>`.

.. _text_sensor-state_condition:

``text_sensor.state`` Condition
-------------------------------

This :ref:`Condition <config-condition>` allows you to check if a given text sensor
has a specific state.

.. code-block:: yaml

    on_...:
      - if:
          condition:
            # Checks if "my_text_sensor" has state "Hello World"
            text_sensor.state:
              id: my_text_sensor
              state: 'Hello World'

Configuration variables:

- **id** (**Required**, :ref:`config-id`): The text sensor ID.
- **state** (**Required**, :ref:`templatable <config-templatable>`, string): The state to compare
  to.

.. note::

    This condition can also be expressed in :ref:`lambdas <config-lambda>`:

    .. code-block:: cpp

        if (id(my_text_sensor).state == "Hello World") {
          // do something
        }

.. _text_sensor-lambda_calls:

lambda calls
************

From :ref:`lambdas <config-lambda>`, you can call several methods on all text sensors to do some
advanced stuff (see the full API Reference for more info).

- ``publish_state()``: Manually cause the sensor to push out a value.

  .. code-block:: cpp

      // Within lambda, push a value of "Hello World"
      id(my_sensor).publish_state("Hello World");

- ``.state``: Retrieve the current value of the sensor as an ``std::string`` object.

  .. code-block:: cpp

      // For example, create a custom log message when a value is received:
      std::string val = id(my_sensor).state;
      ESP_LOGI("main", "Value of my sensor: %s", val.c_str());

See Also
--------

- :apiref:`text_sensor/text_sensor.h`
- :ghedit:`Edit`

.. toctree::
    :maxdepth: 1
    :glob:

    *