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# Map Transformation Service
Transforms the input by mapping it to another string. It expects the mappings to be read from a file which is stored under the transform folder.
The file name must have the .map extension.
This file should be in property syntax, i.e. simple lines with "key=value" pairs. The file format is documented here (opens new window). To organize the various transformations one might use subfolders.
A default value can be provided if no matching entry is found by using "=value" syntax.
Defining this default value using _source_ would then return the non transformed input string.
# Example
transform/binary.map:
key=value
1=ON
0=OFF
ON=1
OFF=0
white\ space=using escape
=default
| input | output |
|---|---|
1 | ON |
OFF | 0 |
key | value |
white space | using escape |
anything | default |
# Usage as a Profile
The functionality of this TransformationService can be used in a Profile on an ItemChannelLink too.
To do so, it can be configured in the .items file as follows:
String <itemName> { channel="<channelUID>"[profile="transform:MAP", function="<filename>", sourceFormat="<valueFormat>"]}
The mapping filename (within the transform folder) has to be set in the function parameter.
The parameter sourceFormat is optional and can be used to format the input value before the transformation, i.e. %.3f.
If omitted the default is %s, so the input value will be put into the transformation without any format changes.
Please note: This profile is a one-way transformation, i.e. only values from a device towards the item are changed, the other direction is left untouched.