At almost every location in a Knowledge Item where strings could be\nentered, the engine also processes \"VarStrings\". VarStrings are strings\nthat can be dynamically expanded during the runtime with specific\nvariable values. This works as follows:
\nIt is possible to construct strings using string interpolation:
\non\n Foo\n Bar == \"Hello, ${Foo}\"It is possible to use math expressions on the right side of a match:
\non\n Foo\n Bar == Foo + 1log(\"This is the ID of the current node: ${NodeID}\")In addition to this simple string replacement, we can perform some mathematical operations:
\n# Addition\nLOCAL::result = number1 + number2\nlog(\"${number1} + ${number2} = ${LOCAL::result}\")# Subtraction\nLOCAL::result = number1 - number2\nlog(\"${number1} - ${number2} = ${LOCAL::result}\")# Division\nLOCAL::result = number1 / number2\nlog(\"${number1} / ${number2} = ${LOCAL::result}\")| \n\n | \n\n \n \nWhen the result of a division is about to be assigned to a variable, if division by 0 was attempted, the value of the variable will be set to 'MathError'. It’s important to note that using 'MathError' in subsequent operations can lead to further arithmetic errors in the following KIs \n | \n
# Multiplication\nLOCAL::result = number1 * number2\nlog(\"${number1} * ${number2} = ${LOCAL::result}\")# Mod\nLOCAL::result = number1 % number2\nlog(\"${number1} % ${number2} = ${LOCAL::result}\")There is also a mathematical library integrated into the engine which allows the\nevaluation of mathematical formulas. For this purpose, the corresponding\nexpression is enclosed in $[ ]:
\n# Multiplication\nlog(\"Calculated Value: $[${number1} * ${number2}]\")The engine also integrates a mathematical library (https://github.com/Rob-bie/expr) that enables the evaluation of mathematical formulas. To use this funcionality, the relevant expression must be enclosed in $[ ].\nWhen including a variable in the mathematical formula, the variable should be enclosed in ${}
# Absolute value\nValue = \"$[abs(-20)]\"\n\n# Absolute value using variables\nTS1 = \"1732542005189\"\nTS2 = \"1732539624000\"\n\nTS3 = \"$[abs(${TS1} - ${TS2})]\"Also, various modifiers can be used in variable strings to convert the\noutput. Let’s assume we have a variable \"data\" with a string as value. We can modify the value \"hello world\" in the following ways:
\n| \n\n | \n\nModifiers must be put before scope declaration, not before variable: ${+LOCAL::test}\n | \n
| \n | Description | \nSample from \"Hello world\" | \n
|---|---|---|
+ | \nConvert to uppercase | \n\"HELLO WORLD\" | \n
- | \nConvert to lowercase | \n\"hello world\" | \n
^ | \nConvert to upper camelcase | \n\"Hello World\" | \n
\\ | \nShell encoding (extra backslash for \" and \\ ) | \n\\\"Hello world\\\" | \n
& | \nHTML encoding | \n"Hello world" | \n
_ | \nConvert non alphanumerical chars to underscore | \nHello_world | \n
upper = \"${+data}\"\nlower = \"${-data}\"\ncamel = \"${^data}\"\nshell = \"${\\data}\"\nhtml = \"${&data}\"\nunder = \"${_data}\"| \n\n | \n\n \n \nThese can also be combined as required, so if the value is\n\"hello world\" as above, you can combine uppercase and underscore conversion ${+_HELLOWORLD} for a result like: HELLO_WORLD. \n | \n
VarStrings allow simple parsing of JSON structures.
\nHandling of JSON structures is initialized by adding # to a variable name inside the VarString followed by operators to address Key:Value pairs inside the structure.
| Operator | \nFunction | \n
|---|---|
| \nName of \"key\" in the root JSON object | \n
| \nName of \"subkey\" in a JSON sub-object | \n
| \nn-th element of a JSON (sub-)array item (first element is 0). | \n
| \nn-th element of a JSON (sub-)array item counted from the end of the array (-1 is the last item). | \n
The following structure shows a minimalist example. We assume the data is stored in the variable \"JSONData\"
\n{\n \"UserInfo\": {\n \"User\": \"Jane Doe\",\n \"Location\": {\n \"Country\": \"Germany\",\n \"City\": \"Frankfurt\"\n },\n \"Pets\": [\n {\n \"Name\": \"Daisy\",\n \"Type\": \"Cat\",\n \"Age\": \"3\"\n },\n {\n \"Name\": \"Duke\",\n \"Type\": \"Dog\",\n \"Age\": \"1\"\n },\n {\n \"Name\": \"Felix\",\n \"Type\": \"Cat\",\n \"Age\": \"97\",\n \"Color\": \"Black\"\n }\n ]\n }\n}Extract the value for \"Country\"
\n${JSONData#UserInfo['Location']['Country']} → \"Germany\"
Extract a full entry from the \"Pets\" array
\n${JSONData#UserInfo['Pets'][1]} → \"{\"Name\":\"Duke\",\"Type\":\"Dog\",\"Age\":\"1\"}\"
Extract the name for the second entry in the \"Pets\" array
\n${JSONData#UserInfo['Pets'][1]['Name']} → \"Duke\"
| \n\n | \n\nYou can only extract single values or objects using this syntax, you can not extract arrays.\n | \n
| \n\n | \n\nIf you need to perform more complex operations on JSON structures, please refer to the JavaScript element.\n | \n