Text Expression Representation - 6.3

Talend Data Mapper User Guide

EnrichVersion
6.3
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Talend Big Data Platform
Talend Data Fabric
Talend Data Management Platform
Talend Data Services Platform
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task
Design and Development
EnrichPlatform
Talend Studio

When text expression representation is selected in the preferences, each expression panel contains a text string that is the expression.

The definition for the text form of expressions is:

      Function = FunctionName [ '[' Properties ']' ] 
               '(' Argument ',' Argument ',' ... ')'

      Properties = ( [ PropertyName '=' ] '"' PropertyValue '"' ',' ... )

      Argument = Function | ElementRef | 

      ElementRef = ( 'in$:' | 'out$:' | 'elem$:' | 'inv$:' ) ElementName

      PropertyName = Name of the property of the function.

      PropertyValue = Value of the property of the function.

      ElementName = Path name of map/structure element. Example: /Transaction-856/BEG/BEG01

      FunctionName = Name of built-in function, or full path name of user function.   

Notes:

  1. If there is a single property for a function, the PropertyName can be omitted.

  2. For element references, in references an input map element, out references an output map element, and elem references a structure element (used in a validation expression associated with a structure). inv represents a reference to a map element that is not present (this can appear due to structure changes after a map has been defined).

  3. If the function refers to a built-in function, only the name of the function need be specified, for example: Concat. However, if a user function is specified, the fully qualified name, including the directory name of the function, must be specified. For example: /userDir/userFunc1.

Some examples:

  • Concat(in$:/a/b) - Calls the Copy function with the map element /a/b on the input of the map.

  • Equal(in$:/a/b,Constant["14"]) - Calls the Equal function with two arguments. The first is element /a/b on the input of the map, and the second is the Constant function with a (value) property of 14. This returns true if the value of input map element a/b is equal to 14.