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Calculated Field

The Calculated Field Transformation enables a user to create new column values by applying expressions, the result of which can be a newly defined column or it can replace the value in an existing one.

For example, the Agent could convert a temperature attribute on the incoming payload from Celsius to Fahrenheit - and either replace the temperature value or add a new attribute to the outgoing payload.

Statements can be written using a subset of the C# syntax. Refer to the example section for sample expressions and supported operations.

Details for an example and its configuration can be found in the How to Use section.

Pre-requisites

None at this time

Limitations

Not every C# syntax is supported. Here are some examples of NOT supported features:

  • Multiline expressions

  • for/foreach/while/do operators

  • Array/list/dictionary initialization

  • Explicit generic invocation (like method<type>(arg))

  • Lambda/delegate declaration (delegate and lamda are only supported as variables or parameters or as a return type of the expression)

  • Array/list/dictionary element assignment (set indexer operator)

  • Other operations on dynamic objects (only property, method invocation, and index now are supported)

Current Version

  • Download the Calculated Field Transformation v3.45

Please contact XMPro if you're looking for an older version of this Agent.

Release Notes

v3.45, 10 Apr 2024

  • Downgraded Newtonsoft.Json to v11.0.1

  • Backward compatible with older Stream Host versions

v3.44, 29 Feb 2024

  • Added a circular dependency check in the ParseExpression function

Note: this version is only supported on Stream Host v4.4.0 and v4.4.1.

2023

v3.43, 26 Jun 2023

  • Fixed parsing error when braces are inside quotations

  • Fixed parsing of column names used in an expression

2022

v3.42, 07 Sept 2022

  • Repackaged to include the Agent's Category

Older

v3.41, 28 Apr 2021

  • Fixed repetitive NEW_ prefixes added to an new column internally

v3.40, 13 Nov 2020

  • Added better error messages

v3.39, 26 Oct 2020

  • Grid converted to edit list and added multiline expression support

v3.381, 30 Jul 2021

  • Fixed repetitive NEW_ prefixes added to an new column internally using base code of v3.38

  • This is an interim version which doesn't support 'EditList' control available in latest XMIoT Framework

v3.38, 26 Oct 2020

  • Fix existing columns being deleted

v3.37, 06 Aug 2020

  • Fix to nested variable expressions when also using { }

v3.35, 15 Jul 2020

  • Added support for variable expressions using [ ]

v3.34, 26 May 2020

  • Upgraded validation to check if each expression is valid

v3.33, 21 May 2020

  • Added proper hyphen support

v3.31, 13 May 2020

  • Added column name support for ' ', '_', and numbers at the start of the column

v3.30, 27 Feb 2020

  • Fixed issue with expression not parsing on start

v3.29, 24 Feb 2020

  • Fixed expression parsing so users can use True/False properly for Boolean values

v3.27, 03 Feb 2020

  • Fixing issue where expressions replace a column's value

v3.26, 03 Feb 2020

  • Added better exception messages and fixed errors with Boolean expressions to support XMIoT Boolean Casing

v3.25, 27 Jan 2020

  • Reworked how expressions are parsed so it is no longer reliant on System.Dynamic.Linq.Core reflections

v3.14, 09 Sep 2019

  • Added the ability to use one calculated field in another calculated field's expression

v3.13, 09 Sep 2019

  • Fixed issues with Payload selection

v3.12, 04 Sep 2019

  • Upgraded System.Linq.Dynamic.Core

v3.11, 27 Aug 2019

  • Added option to specify Existing With New or only New columns as output

v3.10, 04 Mar 2019

  • Added validation for field identifiers

  • Added Error output when calculation fails

v3.09, 21 Jun 2019

  • Change name to Calculated Field and update icon

v3.08, 04 Mar 2019

  • Updated help URL

v3.07, 22 May 2018

  • Fixed outputs that overwrite input fields not having the specified output type

v3.06, 11 May 2018

  • Added DateTime type to list of derived output types

v3.05, 10 May 2018

  • Fixed null-reference exceptions in GetOutputAttributes

v3.04, 10 May 2018

  • Fixed "ToInt is not a valid method" exception

v3.03, 10 May 2018

  • Fixed "Operator cannot be applied to operands of type Object and ..." exceptions

v3.02, 26 Apr 2018

  • Updated DLL

v3.01, 19 Apr 2018

  • Changed Agent state to Virtual

v3.0, 19 Apr 2018

  • Initial Release

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