Each expression in ActivityInfo's formula language has a specific type that determines which values the expression is allowed to have. For example, an expressions like 2+2 or 42 both have the type "number", which can include any real-valued number. The expression CONCAT(FIRST_NAME, " ", LAST_NAME) on the other hand, has the type "string" its value will always be a combination of characters.

Activity's formula values are related, but distinct, from field types. Different form field types, like the text field and the serial number type, have very different behaviors with regard to data collection and management, but when used in formulas, they both have the "string" type.

Understanding ActivityInfo's formula types can be helpful in writing complex formulas. Certain functions, for example, can only be used with specific types.


The following is a quick overview of ActivityInfo's formula types:

Type Description Examples
String A "string" of characters "Alice", 'Bob'
Number A real-valued number 42, 1.5, -3000
Boolean Either true or false TRUE, FALSE
Local Date A year, month, and day DATE(2022,1,15)
Week A year and week number WEEKVALUE("2022W3")
Month A year and month
Quarter A year and a quarter
Instant A specific moment in time _lastEditTime

The following section provides more details these types.


String values in formulas, like in ActivityInfo forms, are a set of a Unicode characters.


Number values in formulas include a real-valued numbers between +/- 1.8 x 10³⁰⁸. In practice, all numeric values are stored as 64-bit floating point numbers.

Local date

The local date type, which we generally refer to as "date" in the documentation, is a date without a time-zone in the Gregorian calendar (standardized as ISO-8601) calendar system, such as 2007-12-03.

ActivityInfo local date values are limited to the range between 1000-01-01 and 9999-12-31.

Blank values

Each type also includes an exceptional "blank" value. ActivityInfo's blank value is similar to NULL in SQL, the NA value in R, or a blank cell in Excel.

The semantics of ActivityInfo's formula language is closer to Excel than SQL. For example, in an SQL query, 1 + NULL is NULL, while in Excel 1 + A1 is 1, even if A1 is blank. ActivityInfo adopts this more "forgiving" handling of blank values in arithmatic.

For more information, please refer to the article on blank values.

Field types and formula types

The following table provides a summary of the correspondence between different types of fields in ActivityInfo forms and formula types:

Field type Formula Type
Serial number String
Quanitity Number
Text String
Multi-line text String
Date Local date
Week Week
Fortnight Week
Month Month
Single Selection String
Multiple selection String
Attachment Struct
Calculated Depends on formula
Reference String
Geographic point Struct
User String
Section header No value
Subform No value
Barcode String

Converting between types

In some cases, you may want to change a value from one type to another. For example, to change a numeric value to string value. The following functions provide

Converting to text

The TEXT function converts its argument to the string.

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Blank values