If you would like to upgrade to a newer long-term support version of Studio Pro, see Moving from Mendix Studio Pro 8 to 9.

String Function Calls

Last modified: August 27, 2024

Introduction

This document describes functions that are used to convert and inspect strings. Note that these functions never change the string itself, they only return a new value.

Strings are surrounded by quotes. If the string contains a quote, it should be escaped by another quote. For example: 'this isn''t funny'.

For a great deep-dive look into string functions call, check out this video:

toLowerCase

Converts all characters in the string to lowercase.

Input Parameters

The input parameters are described in the table below:

Value	Type
String to convert	String

Output

The output is described in the table below:

Value	Type
The same string, but all lowercase.	String

Example

If you use the following input:

toLowerCase('thisISmyString')

The output is the following:

'thisismystring'

toUpperCase

Converts all characters in the string to uppercase.

Input Parameters

The input parameters are described in the table below:

Value	Type
String to convert	String

Output

The output is described in the table below:

Value	Type
The same string, but all uppercase.	String

Example

If you use the following input:

toUpperCase('thisISmyString')

The output is the following:

'THISISMYSTRING'

length

Determines the length of a string.

Input Parameters

The input parameters are described in the table below:

Value	Type
String to convert	String

Output

The output is described in the table below:

Value	Type
Length of the string	Integer

Example

If you use the following input:

length('thisismystring')

The output is the following:

substring

Retrieves a substring of a string. Note that the first character of a string is located at position '0', and the last character is located at position length(string)-1.

Input Parameters

The input parameters are described in the table below:

Value	Type
Subject	String
Start position of the substring	Integer
Desired length of the result (optional)	Integer

Output

The output is described in the table below:

Value	Type
A part of the original string, starting at the start position with a length equal to the desired length. If no desired length is specified, will return a substring starting at the start position and ending at the end of the string.	String

Example

If you use the following input:

substring('thisismystring', 6)

The output is the following:

'mystring'

If you use a third parameter to specify the desired length of the output:

substring('thisismystring', 6, 2)

The output is the following:

'my'

To prevent the value of the third parameter from getting out of range, you can set a limit to the third parameter, for instance, using the min and length functions:

substring('thisismystring', 0, min(length('thisismystring'), 20))

find

Finds the position of the first occurrence of the substring in the string.

Input Parameters

The input parameters are described in the table below:

Value	Type
Original string, the string that you want to search in	String
Substring that you want to search for	String
Start location to begin the search from (optional)	Integer

Output

The output is described in the table below:

Value	Type
The first location of the substring in the original string. Will return `'-1'` if the substring does not occur at all in the original string.	Integer

Example

If you use the following input:

find('thisismystring', 'my')

The output is:

Substring that doesn’t occur in the original string:

find('thisismystring', 'yourstring')

returns:

-1

Another example of an input is:

find('thisismystring', 'i', 5)

The output is:

findLast

Finds the position of the last occurrence of a substring in the original string.

Input Parameters

The input parameters are described in the table below:

Value	Type
Original string, the string that you want to search in	String
Substring that you want to search for	String
Start location to begin the search from (optional)	Integer

Output

The output is described in the table below:

Value	Type
The first location of the substring in the original string. Will return `'-1'` if the substring does not occur at all in the original string.	Integer

Example

If you use the following input:

findLast('thisismystring', 't')

The output is:

Another example of an input where a substring does not occur in the original string:

findLast('thisismystring', 'yourstring')

The output is:

-1

An example of an input with the third parameter:

findLast('thisismystring', 'i', 5)

The output is:

contains

Determines whether the original string (first parameter) contains a substring (second parameter).

For example, this expression:

contains('stringtosearchin', 'stringtosearchfor')

is equivalent to the following expression:

find('stringtosearchin', 'stringtosearchfor') != -1

The example below shows searching for an empty variable or empty string, where $param = '':

contains('stringtosearchin', $param)

The input above will return true.

This function is case-sensitive.

Input Parameters

The input parameters are described in the table below:

Value	Type
Original string, the string that you want to search in	String
Substring that you want to search for	String

Output

The output is described in the table below:

Value	Type
Whether the original string contains the substring.	Boolean

Example

If you use the following input:

contains('thisismystring', 'my')

The output is:

true

startsWith

Determines whether a string starts with the specified substring.

Input Parameters

The input parameters are described in the table below:

Value	Type
Original string, the string that you want to search in	String
Substring that you want to search for	String

Output

The output is described in the table below:

Value	Type
Whether the original string starts with the substring.	Boolean

Example

If you use the following input:

startsWith('thisismystring', 'this')

The output is:

true

endsWith

Determines whether a string ends with the specified substring.

Input Parameters

The input parameters are described in the table below:

Value	Type
Original string, the string that you want to search in	String
Substring that you want to search for	String

Output

The output is described in the table below:

Value	Type
Whether the original string ends with the substring.	Boolean

Example

If you use the following input:

endsWith('thisismystring', 'ring')

The output is:

true

trim

Removes all the whitespace at the beginning and end of a string.

Input Parameters

The input parameters are described in the table below:

Value	Type
A string	String

Output

The output is described in the table below:

Value	Type
Same string but without spaces at the beginning and end.	String

Example

If you use the following input:

trim(' this is my string     ')

The output is:

'this is my string'

isMatch

Checks to see if a string matches a given regular expression.

Input Parameters

The input parameters are described in the table below:

Value	Type
String to try and match	String
Regular expression to match	String

The regular expression must be provided as a string. Although it uses the same format for regular expressions, you cannot use a regular expression resource document in this function.

Please note that this function call uses the regular expression language provided by the current platform:

When used inside a microflow – Java’s regular expressions (for details, see Class Pattern documentation)
When used in the client – JavaScript’s regular expressions (for details, see Regular Expressions documentation)

Output

The output is described in the table below:

Value	Type
Whether the string matches or not.	Boolean

Example

This input below tests to see whether the string contains only numbers:

isMatch('234hello6432', '^([0-9]+)$')

The output is:

False

In isMatch(), the regex is implicitly anchored at ^ and $.

Other Examples

isMatch('NLG 123.45', '[0-9]') returns false
isMatch('NLG 123.45', '.*[0-9].*') returns true

NB searching an empty string:

isMatch('', '.*[0-9].*') returns false

replaceAll

Replaces all occurrences of a regular expression with another string.

Input Parameters

The input parameters are described in the table below:

Value	Type
The string to search in	String
The regular expression to match; if you want to search for a literal string, enclose it between `\Q` and `\E` (for example, `\QPaul S. Mueller\E` will search for the string `Paul S. Mueller`, without interpreting the dot as a wildcard)	String
The string to be substituted for each match (this does not support backreferences, substitutions, or captures)	String

The regular expression must be provided as a string. Although it uses the same format for regular expressions, you cannot use a regular expression resource document in this function.

Please note that this function call uses the regular expression language provided by the current platform:

When used inside microflows – Java’s regular expressions (for details, see Class Pattern)
When used in the client – JavaScript’s regular expressions (for details, see Regular Expressions)

Output

The output is described in the table below:

Value	Type
The original string, with all occurrences of the regular expression replaced by the replacement string. If the regular expression does not occur in the string, the original is returned.	String

Example

If you use the following input:

replaceAll('this is a string with 75 some numbers 234 thrown in', '([0-9])', 'NUMBER')

The output is:

'this is a string with NUMBERNUMBER some numbers NUMBERNUMBERNUMBER thrown in'

Another example of an input of the following:

replaceAll('this is a string with no numbers thrown in', '([0-9])', 'NUMBER')

And the output is that there are no matches for the input:

'this is a string with no numbers thrown in'

replaceFirst

Replaces the first occurrence of the regular expression with a replacement string.

Input Parameters

The input parameters are described in the table below:

Value	Type
The string to search in	String
The regular expression to match; if you want to search for a literal string, enclose it between `\Q` and `\E` (for example, `\QPaul S. Mueller\E` will search for the string `Paul S. Mueller`, without interpreting the dot as a wildcard)	String
The string to be substituted for each match (this does not support backreferences, substitutions, or captures)	String

The regular expression must be provided as a string. Although it uses the same format for regular expressions, you cannot use a regular expression resource document in this function.

Please note that this function call uses the regular expression language provided by the current platform:

When used inside a microflow – Java’s regular expressions (for details, see Class Pattern documentation)
When used in the client – JavaScript’s regular expressions (for details, see Regular Expressions documentation)

Output

The output is described in the table below:

Value	Type
The original string, with the first occurrence of the regular expression replaced by the replacement string. If the regular expression does not occur in the string, the original is returned.	String

Example

If you use the following input:

replaceFirst('this is a string with 75 some numbers 234 thrown in', '([0-9])', 'NUMBER')

The output is:

'this is a string with NUMBER5 some numbers 234 thrown in'

String Concatenation ( + )

The + operator can be used to concatenate two strings or a string and a number.

Input Parameters

The input parameters are described in the table below:

Value	Type
First parameter	String, integer/long, decimal
Second parameter	String, integer/long, decimal

At least one of the parameters must be of type string.

Output

The output is described in the table below:

Value	Type
A new string that is the literal concatenation of the two input parameters.	String

Example

An example of an input to combine two strings can be the following:

'foo' + 'bar'

The output is:

'foobar'

An example of an input to combine a string and a number can be the following:

4.73 + ' kilometers'

The output is:

'4.73 kilometers'

urlEncode

Converts a string to be used in a URL. This function is useful when you want to use the string as part of the URL.

For example:

'http://google.com/search?q=' + urlEncode($myQuery)

Input Parameters

The input parameters are described in the table below:

Value	Type
String to convert	String

Output

The output is described in the table below:

Value	Type
The string, URL-encoded.	String

Example

If you use the following input:

urlEncode('Hello, world!')

The output is:

'Hello%2C+world%21'

urlDecode

Converts a string back from a URL. The opposite of urlEncode.

Input Parameters

The input parameters are described in the table below:

Value	Type
A URL-encoded string to convert	String

Output

The output is described in the table below:

Value	Type
The string, URL-decoded.	String

Example

If you use the following input:

urlDecode('Hello%2C+world%21')

The output is:

'Hello, world!'