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Data Collection - New field type formula

1 Requirements

New datatype Formula. With this datatype, it should be possible to store combined fields. As "Lastname, Firstname". Or formulas as: =field1+field2.

2 Additional Information

• If you want to know more about this feature, its implementation or funding, please contact: Martin Studer, sr.solutions

• Funding: Universität Hohenheim
• Maintainer: Martin Studer
• Development: sr.solutions

3 Discussion

HJL 17 Jul:
= Text1 & " + " & Text2
= Integer1 + Integer2 (+, -, *, /, .....)
= sum (Integer1; Integer2; Integer3)
= mean (Integer1; Integer2; Integer3)

JF 25 Nov 2013: We support the idea as outlined in the comment of HJL 17 Jul 2013 and schedule it for 4.5, if security is ensured. It must not be a simple PHP eval that does not ensure that any malicious code is executed in ILIAS.
 
Please re-schedule this request if any additional substantial features should be included.

HL, 24.3.2014: Need more information about the crowdfunding initiative?
 
See Blog-posting (Feature 2): http://www.ilias.de/docu/goto_docu_blog_3439_173.html
 
or Crowdfunding-page: http://www.ilias.de/docu/goto_docu_dcl_3700_228.html
 
If you want to contribute to this crowdfunding initiative by financing one or more of the listed features, please contact Hansjörg Lauener or Matthias Kunkel for further details.

4 Implementation

This feature is now available in the trunk.
There is an additional Datatype "Formula" available when creating a new field that let's you define a (mathematical) expression.

In the example above, the average of two Integer fields is calculated. The expression parser supports the following features:

• Operators: + , - , * , / , ^
• Brackets to group calculations
• Substituting record values of supported fields: [ [Title of my field] ]
• Concatenating strings and math expressions: "First string " & 2 * [ [Field] ] & "Second string"

Note: The double brackets must not contain a space! This just avoids the creation of a wiki link.
Operators are evaluated according to their precedence, don't forget to use brackets if appropriate: ^ --> * / --> + -