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70 lines
1.8 KiB
Markdown
70 lines
1.8 KiB
Markdown
# Jinja Transformation Service
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Transforms a value using a jinja template.
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The main purpose of this transformer is the use in the home assistant discovery. Therfore not all features of the home assistant templating are supported.
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Basically on [Processing incoming data](https://www.home-assistant.io/docs/configuration/templating/#processing-incoming-data)
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## Available variables
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| Variable | Description |
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|------------|------------------------------------|
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| value | The incoming value. |
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| value_json | The incoming value parsed as JSON. |
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## Examples
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### Basic Examples
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#### Incoming data
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Given the value
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```json
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{"Time":"2019-01-05T22:45:12","AM2301":{"Temperature":4.7,"Humidity":93.7},"TempUnit":"C"}
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```
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the template
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```
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{{value_json['AM2301'].Temperature}}`
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```
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extracts the string `4.7`.
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#### Outgoing data
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The JINJA transformation can be used to publish simple JSON strings through, for example, the HTTP Binding's `commandTransformation` parameter.
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Say we have a String Item which holds the following value:
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```
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This is my string
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```
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Adding the following into the `commandTransformation` parameter of your HTTP Thing Channel
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```
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JINJA:{"msgtype":"m.text", "body":"{{value}}"}
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```
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will send the following string out of openHAB
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```json
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{"msgtype":"m.text", "body":"This is my string"}
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```
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`{{value}}` will be replaced by whatever the value of your Item is.
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Note that if using \*.things files you must escape quotation marks, for example:
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```
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commandTransformation = "JINJA:{\"msgtype\":\"m.text\", \"body\":\"{{value}}\"}"
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```
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## Further Reading
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- Wikipedia on [Jinja](https://en.wikipedia.org/wiki/Jinja_(template_engine).
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- Home assistant [discovery](https://www.home-assistant.io/docs/mqtt/discovery/).
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- Home assistant [templating](https://www.home-assistant.io/docs/configuration/templating/).
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