Create a custom converter
Overriding fromJson()
Imagine you have a JSON object that contains an element "modified":"2022-02-02T02:02:22Z", but your class has Public modifiedDate as Variant.
First, create your custom converter class:
For the body of the fromJson() function, get the string value from the "modified" element and convert it to a DateTimeObject. So the complete function is:
Function fromJson(source As JsonObject) As Variant
Dim dt as String
Dim dateVal as String
Dim timeVal as String
Dim dateElems as Variant
Dim timeElems as Variant
dt = source.scalarValue
dateVal = StrLeft(dt, "T")
dateElems = Split(dateVal, "-")
timeVal = Left$(StrRight(dt, "T"), 8)
timeElems = Split(timeVal, ":")
Return DateNumber(dateElems(0), dateElems(1), dateElems(2)) + TimeNumber(timeElems(0), timeElems(1), timeElems(2))
End Function
You can use it with the following code:
Dim helper as New JsonConversionHelper
Dim dateConverter as New DateTimeSerializer()
Call dateConverter.forPropertyName("modifiedDate") 'Redirect value to modifiedDate property of our class
Call helper.withCustomConverter("modified", dateConverter)
Set obj = helper.fromJsonString(json, "ObjectSummary", "deser-50")
This creates an instance of DateTimeSerializer, maps it to the modifiedDate property of the class and maps it from the modified element of the json.
Warning
Date variants are not intended to be timezone-specific. You should consider using ZuluVSE instead.
Overriding deserialize()
Occasionally, just converting the value won't be enough. You might need to do something more extensive with the value you're deserializing. Imagine you have a JSON object that has an element "startTime":"2022-06-03T10:10:30Z", but the class you're writing to has Public startDate as Variant and Public startTime as Variant.
You need to take a single string coming in and split it across two Date variants, one for the date and one for the time. The standard converters aren't set up for that. fromJson() will return a single value to write to a single field.
First, create your custom converter class:
Override the standard deserialize() sub, which needs the same signature as the sub in the base class, so Sub deserialize(holder as JsonConversionHolder, source as JsonObject). The holder parameter is a JsonConversionHolder object, which has a contents property containing the instance of the class you're deserializing to. Your code will be:
On line 8, you put the holder contents - the object you're writing to - in the global variable samsaraObj.
On line 10, you extract the ISO date-time into a temporary variable dateTime. Then on lines 11 and 12, you extract the date portion and split it into an array with three elements - year, month, day. You also extract the time portion on line 13.
Finally on line 17, you build the string to create and write the date variants. DateNumber() allows us to pass year, month, and day in that order. These are expected as numbers, so you just add the variables to the string. At the point execString is samsaraObj.startDate = DateNumber(2022,06,03).
On line 18, you use CDat() for the time portion. This function takes a string, so you need to add explicitly string delimiters into execString. This string will become samsaraObj.startTime = CDat("10:10:30").
In the final block on line 28, you call Me.cleanup() to clear the global variables.