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Document new transformRaw command in rules (#687) 

* Document new transformRaw command in rules

Signed-off-by: Stefan Triller <stefan.triller@telekom.de>
pull/688/merge
Stefan Triller 2018-05-25 16:41:58 +02:00 committed by Kai Kreuzer
parent f1f305fd45
commit 20de280a6a
1 changed files with 26 additions and 4 deletions
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configuration/rules-dsl.md
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@ -386,7 +386,6 @@ When individual color values from a HSBType as a PercentType are retrieved, it w
Correspondingly, the for 16 or 32 bit representation, the percent type needs to be multiplied the percent type by 16^2 or 32^2, respectively.
```java
//Example for conversion to 8-bit representation
// In rule body
val red = (MyColorItem.state as HSBType).red * 255
@ -512,7 +511,7 @@ val PointType location = Device_Coordinates.state as PointType
##### Number Item
A Number Items carries either a **DecimalType** or a **QuantityType** in case the Number Item has a dimension attached (e.g. `Number:Temperature`).
A Number Items carries either a **DecimalType** or a **QuantityType** in case the Number Item has a dimension attached (e.g. `Number:Temperature` in the items file). In rules, units are added to a number by a `|`, where the unit has to be put in quotes, if it contains non-alphabetic characters, e.g. `10|m`, but `20|"km/h"'. A couple of commonly used units do not necessarily require quotes, these are '°C', '°F', 'Ω', '°', '%', 'm²' and 'm³', so it is ok to write `20|"°C"`, but `20|°C` will also work.
DecimalType and QuantityType are also java.lang.Number so all the conversions listed above under Dimmer Item apply to Number Item as well.
Here some other commonly needed conversions:
@ -536,7 +535,7 @@ var DecimalType parsedResult = DecimalType.valueOf(Long.parseLong(hex_code, 16).
```java
// define a QuantityType variable
var myTemperature = 20 [°C]
var myTemperature = 20|°C
// convert a quantity state into a different unit:
var fahrenheit = myTemperature.toUnit("°F")
@ -699,7 +698,8 @@ end
{: #transformations}
### Transformations
openHAB [Transformation services]({{base}}/addons/transformations.html) may also be used in rules to transform/translate/convert data.
openHAB [Transformation services]({{base}}/addons/transformations.html) can be used in rules to transform/translate/convert data.
The general syntax is as follows:
```java
@ -718,8 +718,30 @@ var temperature = transform("JSONPATH", "$.temperature", jsonstring)
var fahrenheit = transform("JS", "convert-C-to-F.js", temperature)
```
The `transform` method tries to transform the given value and if it does not succeed it returns the original unchanged value.
In contrast to the `transform` method, the `transformRaw` method does not catch any `TransformationException`s internally, but throws them, so that the caller can handle it.
```java
transformRaw("<transformation-identifier>", "<transf. expression or transf. file name>", <input-data or variable>)
```
Example:
```java
try {
var temperature = transform("JSONPATH", "$.temperature", jsonstring)
}
catch(TransformationException e) {
logError("Error", "Some bad stuff happened in my rule: " + e.getMessage)
}
finally {
// always runs even if there was an error, good place for cleanup
}
```
For all available Transformation services please refer to the list of [Transformation Add-ons]({{base}}/addons/transformations.html).
{: #logging}
### Logging