Data types

Survey Solutions uses C# language for enabling and validation conditions. C# is a contemporary general purpose object-oriented programming language, widely documented. When writing expressions in C# language, and especially when using standard C# and custom Survey Solutions functions it is important to keep in mind the definitions of the various Survey Solutions objects.

Below the types of Survey Solutions objects are explained in terms of standard C# classes and types. Links are provided to the corresponding definitions on Microsoft’s site.

Note that in the definitions below a question mark indicates a nullable type.

Questions

Question	Type
Categorical: Single-select	int?
Categorical: Single-select (linked)	int[]
Categorical: Single-select (linked to text-list question)	int?
Categorical: Single-select (combo)	int?
Categorical: Single-select (cascade)	int?
Categorical: multi-select	int[]
Categorical: multi-select (Y/N mode)	class { int[] All; int[] Yes; int[] No; int[] Missing; }
Categorical: multi-select (linked)	int[][]
Categorical: multi-select (linked to text-list question)	int[]
Numeric	double?
Numeric (integer)	long?
Date	DateTime?
Date (current time)	DateTime?
Text	string
Text (with pattern)	string
Barcode	string
Picture	string
List	Array of class{int Value; string Text;}
GPS	class { doubleLatitude; doubleLongitude; doubleAccuracy; doubleAltitude; }
Geography	class { double Area; double Length; int PointsCount; }
Audio	class { string FileName; TimeSpan Length; }

Notes:

The value of the categorical multi-select question can be null, or an array of length zero.
The string content of the picture question is the name of the file, not the content of the image.
The value of the categorical multi-select linked question is defined as a jagged array although in practice it is always a regular-sized array.

System variables

Variable	Type
@rowcode	int
@rowindex	int
@rowname	string
@optioncode	int
~~@roster~~ [obsolete, refer to a roster by ID instead]	IEnumerable<class>, class[]
@current	class

Notes

In definition of @current object is a dynamically compiled class definition with all the fields defined as for an instance of the roster.
Correspondingly any roster is an IEnumerableenumeration of objects of this class, also supports addressing by index as an array.

User-defined variables

Variable (selected type)	Actual type (in expressions)
Boolean	bool?
Double	double?
Date/Time	DateTime?
Long integer	long?
String	string

Lookup tables

Lookup tables are defined as dictionaries:
Dictionary<int, class>
where class is a dynamically compiled definition containing rowcode and all the fields present in a lookup table:
class {
  int rowcode;
  double? field1;
  double? field2;
  ….
}

These definitions have last been updated for version 5.25 on Feb 07, 2018.