Cut MQTT variable to fit

Configuration
1

Hello, everyone,

I have a beginner’s question about cutting variables “to fit”.
I get the following values transmitted to a sensor via MQTT:

[{"ID":40561,"Name":"Value","ObjectIdent":"Value","VariableTyp":3,"VariableAction":52503,"VariableCustomAction":0,"VariableProfile":"","VariableCustomProfile":"","Value":"264.5885"}]

But I only need the last value after the last “Value” here, which is 264.5885.
What do I have to add to the configuration YAML now?

sensor:
    - name: "Wasser"
      state_topic: "mqttsync/symcon/Wasser"
      unit_of_measurement: "m³"
      value_template: "{{ value_json.Value }}"

Thanks and greetings Philip

2

In your configuration yaml shouldnt this be:

mqtt:
  sensor:
      - name: "Wasser"
        state_topic: "mqttsync/symcon/Wasser"
        unit_of_measurement: "m³"
        value_template: "{{ value_json.Value }}"
3

Thanks for your answer, but if I use exact this configuration I get UNKNOWN as State.

4

What does
value_template: "{{ value }}"
return?

Edit:
Checking this out in the Developers Tools i can get the correct value from the string you posted. But only when removing the brackets [ ]

{% set value_json = {"ID":40561,"Name":"Value","ObjectIdent":"Value","VariableTyp":3,"VariableAction":52503,"VariableCustomAction":0,"VariableProfile":"","VariableCustomProfile":"","Value":"264.5885"} %}
{{ value_json.Value }}

Results in 264.5885

5

Might have what u need.

6

Hi,

now I tried

value_template: ‘{{ (value | from_json) }}’

but in the Log I get an Error:

Logger: homeassistant.helpers.template
Source: helpers/template.py:583
First occurred: 00:55:17 (1 occurrences)
Last logged: 00:55:17

Template variable warning: 'list object' has no attribute 'Value' when rendering '{{ value_json.Value }}'
7

That should be what you want including the square bracket [ ]

That’s from the earlier link.

{% set value_json = [{"ID":40561,"Name":"Value","ObjectIdent":"Value","VariableTyp":3,"VariableAction":52503,"VariableCustomAction":0,"VariableProfile":"","VariableCustomProfile":"","Value":"121.1211" }] %}

{{ value_json[0].Value | default(none) }}
8

Thank you very much, it worked exactly as you described. I actually just had to correct my spelling. :slight_smile: