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Use object and object array converters

Deserializing inner objects with a custom converter

Imagine the following classes:

Class Person

    Public firstName as String
    Public lastName as String
    Public pet as Pet

End Class

Class Pet

    Public name as String
    Public type as String

End Class

When deserializing, you were able to just pass a JsonBasicObjectConverter, telling it the class to return and the script location. But when serializing, you need to use a helper that defines which properties of the class to serialize. This could be done with a custom converter and its toJson() function. The converter would be:

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Class PetConverter as AbstractJsonConverter

    Function toJson(source as Variant) as Variant
        Dim helper as New JsonConversionHelper()
        Dim jsonObj as JsonObject
        Set jsonObj = helper.withScalarConverter("name")._
            withScalarConverter("type")._
            toJson(source)
        Set toJson = jsonObj
    End Function

End Class

The source object passed into the toJson() function at line 3 will be the Pet object. This creates a JsonConversionHelper, telling it to convert "name" and "type" as scalars (lines 6 and 7), and calls the helper's own toJson() function on line 8 to return the Pet as a JsonObject. The resulting JsonObject is just returned as the output for the function.

This can be used with the following code:

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Dim helper as New JsonConversionHelper
Dim petConverter as New PetConverter
Call helper.withScalarConverter("firstName")._
    withScalarConverter("lastName")._
    withCustomConverter("pet", petConverter)

Dim jsonObj as JsonObject
Set jsonObj = helper.toJson(person)

A JsonConversionHelper is created to serialize the Person on line 1. One line 2 an instance of the PetConverter class is created. And the helper is loaded with JsonScalarConverters for "firstName" and "lastName" and the PetConverter for "pet" on lines 3 to 5. Then the person is serialized into a JsonObject on line 8.

Using a JsonBasicObjectConverter

However, it's possible to serialize the Pet using a JsonBasicObjectConverter. But, just as you did for the custom converter, it needs to be loaded with its own JsonConversionHelper with information of which properties to serialize.

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Dim petHelper as New JsonConversionHelper
Dim petConverter as New JsonBasicObjectConverter("Pet", "ser-30")
Dim helper as New JsonConversionHelper
Dim jsonObj as JsonObject

Set jsonObj = helper.withScalarConverter("firstName")._
    withScalarConverter("lastName")._
    withCustomConverter("pet", petConverter._
        withHelper(petHelper._
            withScalarConverter("name")._
            withScalarConverter("type")))._
    .toJson(person)

First, you instantiate the variables:

  • A JsonConversionHelper is created to serialize the pet on line 1.
  • A JsonBasicObjectConverter is created to convert the Pet on line 2.
  • A JsonConversionHelper is created to process everything on line 3.
  • A JsonObject is declared for the result on line 4.

Then you're ready to get your JsonObject. The main helper is loaded with JsonScalarConverters for "firstName" (line 6) and "lastName" (line 7) and the JsonBasicObjectConverter, petConverter (line 8). On line 9 the petConverter is loaded with its own helper, petHelper, which needs different converters to the main helper. The petHelper is loaded with two JsonScalarConverters for "name" (line 10) and "type" (line 11). And Finally, the main helper's toJson() function is called on line 12, passing the Person you wish to deserialize.

Manual conversion

If the Person object holds an array of Pets instead of just one Pet, you can just use the JsonBasicObjectConverter. The code is similar to the code for serializing a single Pet.

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Dim petHelper as New JsonConversionHelper
Dim petConverter as New JsonBasicObjectArrayConverter("Pet", "ser-30")
Dim helper as New JsonConversionHelper
Dim jsonObj as JsonObject

Set jsonObj = helper.withScalarConverter("firstName")._
    withScalarConverter("lastName")._
    withCustomConverter("pets", petConverter._
        withHelper(petHelper._
            withScalarConverter("name")._
            withScalarConverter("type")))._
    toJson(person)

The only differences are that on line 2, you create petConverter as a JsonBasicObjectArrayConverter instead of a JsonBasicObjectConverter, and you assign the converter to the "pets" property and label on line 8.

Example code