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Question Jack Rack · Oct 11

How can I design a dynamic class schema generator in ObjectScript based on runtime JSON input?

Given a JSON schema at runtime, I want to programmatically create persistent classes with corresponding properties and indices. Is there a way to dynamically compile and load such classes?

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Ashok Kumar T · Oct 11

Hi Jack

IRIS does not provide built-in functionality to generate classes directly from a JSON Schema, unlike the support available for XML Schema (XSD). However, you can programmatically create and compile classes at runtime using the %Dictionary.ClassDefinition API.

Here is the sample code to generate a class.

ClassMethod CreateClass()
{	
	Set clsObj = ##class(%Dictionary.ClassDefinition).%New()
	Set clsObj.Name="Test.NewClass"Set clsObj.Super="%RegisteredObject,%JSON.Adaptor"Set clsObj.Description="Class created via code"Set clsObj.DdlAllowed = 1Set clsObj.Inheritance="left"Set propObj = ##class(%Dictionary.PropertyDefinition).%New()
	Set propObj.Name="Name"Set propObj.Type="%String"Set propObj.SqlColumnNumber=2Do propObj.Parameters.SetAt(70,"MAXLEN")
	
	Set indexObj = ##class(%Dictionary.IndexDefinition).%New()
	Set indexObj.Name="NameIdx"Set indexObj.Properties="Name"Do clsObj.Properties.Insert(propObj)
	Do clsObj.Indices.Insert( indexObj)
	Set st=  clsObj.%Save()
	D$SYSTEM.OBJ.Compile("Test.NewClass","ckb")
	If$$$ISERR(st) w$SYSTEM.OBJ.DisplayError(st)
}

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Lucrezia Puntorieri Oct 12 to Ashok Kumar T

Hi Ashok, this is really interesting but is it possibile in any way to add specific code to the generated class?

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Ashok Kumar T Oct 13 to Lucrezia Puntorieri

Hi @Lucrezia Puntorieri
Yes you can create a method and classmethod programmatically.

Set clsmethodObj = ##class(%Dictionary.MethodDefinition).%New()
Set clsmethodObj.Name="TestClsMethod"Set clsmethodObj.ClassMethod=1Do clsmethodObj.Implementation.WriteLine($C(9)_"Set ^test=""Test"" ")
Do clsmethodObj.Implementation.WriteLine($C(9)_"Quit ^test ")

Set methodObj = ##class(%Dictionary.MethodDefinition).%New()
Set methodObj.Name="TestMethod"Set methodObj.ClassMethod=0Do methodObj.Implementation.WriteLine($C(9)_"For I=1:1:10 { S ^test(i)=i} ")
Do methodObj.Implementation.WriteLine($C(9)_"Quit ^test ")

Do clsObj.Methods.Insert(clsmethodObj)
Do clsObj.Methods.Insert(methodObj)

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