4D Doc Center : JSON Stringify

Home

4D v14.3

JSON

JSON Stringify


JSON Stringify ( value {; *} ) -> Function result

Parameter	Type	Description
value	Object, Object array, String, Real, Date, Time	Data to convert into JSON string
*	Operator	Pretty printing
Function result	Text	String containing serialized JSON text

Description

The JSON Stringify command converts the value parameter into a JSON string. This command serializes data into JSON; it performs the opposite action of the JSON Parse command.

Pass the data to be serialized in value. It can be expressed in scalar form (string, number, date or time) or by means of a 4D object (or an object array).

In the case of an object, you can include all types of values (see the JSON data types paragraph). JSON formatting must respect the following rules:

String values must be enclosed in quotes. All Unicode character can be used except for special characters that must be preceded by a backslash.
Numbers: interval of ±10.421e±10
Booleans: "true" or "false" strings
Pointers to a field, variable or array (the pointer is evaluated when it is stringified)
Dates: Text type
Times: Real type

You can pass the optional * parameter to include formatting characters in the resulting string. This improves the presentation of JSON data (known as pretty formatting).

Example 1

Conversion of scalar values:

 $vc:=JSON Stringify("Eureka!") // "Eureka!"

 $vel:=JSON Stringify(120) // "120"

 $vd:=JSON Stringify(!28/08/2013!) //  "2013-08-27T22:00:00Z"

 $vh:=JSON Stringify(?20:00:00?) // "72000000" seconds since midnight

Example 2

Conversion of a string containing special characters:

 $s:=JSON Stringify("{\"name\":\"john\"}")

  // $s="{\\"name\\":\\"john\\"}"

 $p:=JSON Parse($s)

  // $p={"name":"john"}

Example 3

Example using a pointer to a variable:

 C_OBJECT($MyTestVar)

 C_TEXT($name ;$jsonstring )

 OB SET($MyTestVar;"name";->$name) // object definition

  // $MyTestVar= {"name":"->$name"}

 

 $jsonstring :=JSON Stringify($MyTestVar)

  // $jsonstring ="{"name":""}"

  //...

 

 $name:="Smith"

 $jsonstring :=JSON Stringify($MyTestVar)

  //$jsonstring = "{"name" : "Smith"}"

Example 4

Serialization of a 4D object:

 C_TEXT($varjsonTextserialized)

 C_OBJECT($Contact)

 OB SET($Contact;"firstname";"Alan")

 OB SET($Contact;"lastname";"Monroe")

 OB SET($Contact;"age";40)

 OB SET($Contact;"phone";"[555-0100,555-0120]")

 

 $varjsonTextserialized:=JSON Stringify($Contact)

 

  // $varjsonTextserialized = "{"lastname":"Monroe","phone":"[555-0100,

  // 555-0120]","age":40,"firstname":"Alan"}"

Example 5

Examples of serializing a 4D object with and without the * parameter:

 C_TEXT($MyContact)

 C_TEXT($MyPContact)

 C_OBJECT($Contact;$Children)

 OB SET($Contact;"lastname";"Monroe";"firstname";"Alan")

 OB SET($Children;"firstname";"Jim";"age";"12")

 OB SET($Contact;"children";$Children)

 $MyContact:=JSON Stringify($Contact)

 $MyPContact:=JSON Stringify($Contact;*)

  //$MyContact= {"lastname":"Monroe","firstname":"Alan","children":{"firstname":"John","age":"12"}}

  //$MyPContact= {\n\t"lastname": "Monroe",\n\t"firstname": "Alan",\n\t"children": {\n\t\t"firstname": "John",\n\t\t"age": "12"\n\t}\n}

The advantage of this formatting is clear when the JSON is shown in a Web area:

Standard formatting:
Pretty formatting: