Type Check Functions

C8QL offers functions to check the data type of a value at runtime. The following type check functions are available. Each of these functions takes an argument of any data type and returns true if the value has the type that is checked for, and false otherwise.

IS_NULL()

IS_NULL(value) → bool

Check whether value is null. Identical to value == null.

To test if an attribute exists, see HAS() instead.

• value (any): value to test
• returns bool (boolean): true if value is null, false otherwise

IS_BOOL()

IS_BOOL(value) → bool

Check whether value is a boolean value

• value (any): value to test
• returns bool (boolean): true if value is true or false, false otherwise

IS_NUMBER()

IS_NUMBER(value) → bool

Check whether value is a number

• value (any): value to test
• returns bool (boolean): true if value is a number, false otherwise

IS_STRING()

IS_STRING(value) → bool

Check whether value is a string

• value (any): value to test
• returns bool (boolean): true if value is a string, false otherwise

IS_ARRAY()

IS_ARRAY(value) → bool

Check whether value is an array / list

• value (any): value to test
• returns bool (boolean): true if value is an array / list, false otherwise

IS_LIST()

IS_LIST(value) → bool

This is an alias for IS_ARRAY()

IS_OBJECT()

IS_OBJECT(value) → bool

Check whether value is an object / document

• value (any): value to test
• returns bool (boolean): true if value is an object / document, false otherwise

IS_DOCUMENT()

IS_DOCUMENT(value) → bool

This is an alias for IS_OBJECT()

IS_DATESTRING()

IS_DATESTRING(str) → bool

Check whether value is a string that can be used in a date function. This includes partial dates such as "2015" or "2015-10" and strings containing properly formatted but invalid dates such as "2015-02-31".

• str (string): date string to test
• returns bool (boolean): true if str is a correctly formatted date string, false otherwise including all non-string values, even if some of them may be usable in date functions (numeric timestamps)

IS_KEY()

IS_KEY(str) → bool

Check whether value is a string that can be used as a document key, i.e. as the value of the _key attribute. See Naming Conventions for Document Keys.

• str (string): document key to test
• returns bool (boolean): whether str can be used as document key

TYPENAME()

TYPENAME(value) → typeName

Return the data type name of value.

• value (any): input of arbitrary type
• returns typeName (string): data type name of value ("null", "bool", "number", "string", "array" or "object")

Example Value	Data Type Name
null	"null"
true	"bool"
false	"bool"
123	"number"
-4.56	"number"
0	"number"
"foobar"	"string"
"123"	"string"
""	"string"
[ 1, 2, 3 ]	"array"
["foo",true]	"array"
[ ]	"array"
{"foo":"bar"}	"object"
{"foo": null}	"object"
{ }	"object"