This node provides the possibility to append an
arbitrary number of
flow variables or modify existing variables using expressions.
For
each variable
that shall be appended or modified a separate expression
is defined.
These expressions can be simply created using predefined
functions
similar to
the
Math Formula
and
String Manipulation
Nodes). Nevertheless there is no restriction on the number of lines
an expression has and the number of functions it uses. This allows
users to create their own complex expressions.
Additionally, intermediate results of functions or calculations can
be stored
within an expression by assigning them to variables
(using
'=').
This allows that these
results can be reused in different parts
of the expression
after they
have been assigned (see Examples).
Note:
the names of these variables must be different to all of the
predefined function identifiers. Otherwise an error will occur.
To change an expression of an output variable it has to
be
selected in the list of expressions. By selecting an expression the
Expression Editor shows up and the user can modify the expression in
the provided text area.
Available flow variables
can
be
accessed
via
the provided method
variable("varName").
For
each expression
the last
computed instruction
will
be returned.
The syntax and grammar of the expressions are based on the
Javascript
Languange
.
Examples:
-
5*7+3
will append a variable with the value 38.
-
v = variable("knime.workspace")
substr(v, lastIndexOfChar(v,"/"), length(v))
will create a variable containing the folder name of the KNIME workspace folder.
-
"a1"
"a2"
will create a variable with the value "a2", whereas
a1 = "a1"
a2 = "a2"
a1
will create a variable with the value "a1".
Options
General
Expression Table
Expression Editor
Popular Successors
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- Excel Reader2 %
- Rule-based Row Filter2 %
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- GET Request1 %
- Column Filter1 %
- CSV Writer1 %
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List Files< 1 %Column Rename< 1 %- CASE Switch End< 1 %
- Variable to Table Row< 1 %
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Variable to Table Row< 1 %- Table Creator< 1 %
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- Column Rename (Regex)< 1 %
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Counting Loop Start< 1 %- String Manipulation< 1 %
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CASE Switch Data (Start)< 1 %- Microsoft SQL Server Connector< 1 %
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Variable Condition Loop End< 1 %Row Splitter (deprecated)< 1 %- Histogram< 1 %
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Flow Variable End IF< 1 %- Table Writer< 1 %
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CASE Switch Variable (End)< 1 %Excel Sheet Appender (XLS)< 1 %- Path to String (Variable)< 1 %
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XLS Formatter (apply)< 1 %Flow Variable IF Switch< 1 %- URL to File Path (Variable)< 1 %
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Table Row To Variable Loop Start< 1 %Recursive Loop Start< 1 %- Column Aggregator< 1 %
CASE Switch Variable (Start)< 1 %- End IF< 1 %
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Loop End< 1 %- Counting Loop Start< 1 %
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Links
- String Flow Variable and Rule Engineby armingrudd on 2019-04-22forum.knime.com/p/59138
- Formatting date/time from variableby knimediger on 2020-11-09forum.knime.com/p/107650
- Variable Expression: How to use declared variables in expression of the same nodeby elsamuel on 2021-08-19forum.knime.com/p/132351
- if then else with multiple conditionsby izaychik63 on 2021-09-17forum.knime.com/p/134816
- Define multiple input variables in one nodeby izaychik63 on 2020-01-29forum.knime.com/p/80149
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