Extracting json from mqtt?

ESPHome
1

Hi,

I have a text sensor that subscribes to a topic which is formatted in json.

I want to pull out one pair of data and add that value to a sensor in esphome.

Is there an easy way to have this “temperature”:17.11, extracted from the json text and create a sensor called “Outside Temperature”?

I am guessing some sort of lambda is involved but thats a bit above my head!

From googling it, I can see a sensor that pulls info via http and extracts values all as part of one lambda but not sure if subscribing to mqtt would work the same.

Thanks

2

Would something like this work ?

    - state_topic: "your state topic"  
      name: "Outside Temperature"
      unit_of_measurement: "°C"
      unique_id: outside temperature
      value_template: '{{ value_json.temperature }}'
3

Print your JSON the whole thing including the curly barckets and someone might have a crack at it.

4

There is a json component which uses ArduinoJson (although it works fine with ESP-IDF also).
With that, you will need a bit of a lambda, but it’s quite simple.
Something like this:

json:

text_sensor:
  - id: your_text_sensor_with_json_value
    platform: the_platform_of_your_sensor
    ...
    on_value:
      then:
        - lambda: |-
            DynamicJsonDocument json(1024);
            DeserializationError error = deserializeJson(json, x.c_str());
            if (error) {
              ESP_LOGE("your_tag", "Error parsing json: %s", x.c_str());
              ESP_LOGE("your_tag", "Error: %s", error.c_str());
            } else {
              const float temperature = json["temperature"].as<float>();
              id(outside_temperature).publish_state(temperature);
            }
5

That’s the geat thing about HA , there is more than one way of doing things usually.

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