Data types

Overview

In Qodly, data are handled according to their type in two places: the datastore and the QodlyScript language.

Although they are usually equivalent, some data types available at the datastore level are not directly available in the language and are automatically converted. Conversely, some data types can only be handled through the language. The following table lists all available data types and how they are supported/declared:

Data Types	Variable declaration	Datastore support (type)	Default value
blob	var blob	blob	0 byte
	var 4D.Blob	object	null
boolean	var boolean	bool	false
collection	var collection	-	null
date	var date	date	00-00-00
null	-	-	null
number	var integer, var number	number	0
object	var object	object	null
picture	var picture	image	pictureSize == 0
string	var string	string	""
time	var time	duration	00:00:00
undefined	-	-	undefined
variant	var variant	-	undefined

note

Variant is actually not a data type but a variable type that can contain a value of any other data type.

type

type ( var : any ) : integer

Parameter	Type		Description
var	any	->	Variable to be tested
Result	integer	<-	Data type number

Description

The type command returns a numeric value that indicates the type of variable you have passed in the var parameter.

Qodly provides the following predefined constants:

Constant	Value
kBlob	30
kBoolean	6
kCollection	42
kDate	4
kInteger	9
kNull	255
kObject	38
kPicture	3
kNumber	1
kString	2
kTime	11
kUndefined	5
kVariant	12

You can apply the type function to variables and sequential parameters ($1, $2...) of a method.

note

You cannot apply the type function to scalar expressions such as object properties (emp.name) or collection elements (myColl[5]). To do this, you must use the valueType command.

valueType

valueType ( expression : any ) : integer

Parameter	Type		Description
expression	any	->	Expression whose resulting value to be tested
Result	integer	<-	Data type number

Description

The valueType command returns the type of the value resulting from the evaluation of the expression you passed as parameter.

The command returns a numeric value that can be compared with one of the following constants provided by Qodly:

Constant	Value
kBlob	30
kBoolean	6
kCollection	42
kDate	4
kInteger	9
kNull	255
kObject	38
kPicture	3
kNumber	1
kString	2
kTime	11
kUndefined	5
kVariant	12

This command is designed to return the type of a scalar expression, i.e. the value stored in or returned by the expression parameter. In particular, it can be applied to the following Qodly expressions:

• object properties (emp.name),
• collection elements (myCol[5]).

note

Numerical object properties are always considered number values:

var o : object
var vType : integer
o = newObject("value",42)
vType = valueType(o.value) //vType = kNumber

Example 1

You want to handle the various possible types of an object property value:

switch
    :(valueType(o.value) == kNumber)
  //handle a numeric value
    :(valueType(o.value) == kString)
  //handle a string
    :(valueType(o.value) == kObject)
  //handle a sub-object
       ...
end

Example 2

You want to sum up all numeric values in a collection:

var col : collection
var colSum : number
col = newCollection("Hello",20,"World2",15,50,currentDate,true,10)
for(i,0,col.length-1) //-1 since collections start at 0
    if(valueType(col[i]) == kNumber)
       colSum = colSum+col[i]
    end
end

Converting data types

QodlyScript contains operators and commands to convert between data types, where such conversions are meaningful. QodlyScript enforces data type checking. For example, you cannot write: "abc"+0.5+!12/25/96!-?00:30:45?. This will generate syntax errors.

The following table lists the basic data types, the data types to which they can be converted, and the commands used to do so:

Data Type to Convert	to String	to Number	to Date	to Time	to Boolean
String (1)		num	date	time	bool
Number (2)	string				bool
Date	string				bool
Time	string				bool
Boolean		num

(1) Strings formatted in JSON can be converted into scalar data, objects, or collections using the jsonParse command.

(2) Time values are durations and can be treated as numbers.

note

In addition to the data conversions listed in this table, more sophisticated data conversions can be obtained by combining operators and other commands.