InvalidJsonType class
Json objects simulate JavaScript untyped variables. However, many Json functions only make sense for specific underlying Json data. For example, the Add function only makes sense if the underlying json object is an Array. If a function applied to a Json object is invalid for the underlying object, an InvalidJsonType exception is thrown.
To create an InvalidjsonType exception yourself, you typically use a SOUL Throw statement with an InvalidJsonTyoe New constructor. This statement must be issued from within a method, and it can only be caught by the code that calls the method. For example, the following statement throws an InvalidJsonType exception:
throw %(invalidJsonType):new(type=array, method="MyJsonMethod")
Remember that you catch an exception with the Catch statement; if an exception condition occurs outside a Catch for it, the request is cancelled.
The InvalidJsonType class, like the Json class is available as of Model 204 7.6.
The InvalidJsonTypes methods
The following are the available InvalidJsonType class methods.
| Method | Description |
|---|---|
| MethodName | Type of object for invalid method |
| New | Create a new InvalidJsonType object |
| Type | Type of object for invalid method |
The methods in the class are described in the subsections that follow. In addition:
- "Notation conventions for methods" has information about the conventions followed.
- "InvalidJsonType methods syntax" is a single page that contains the syntax diagrams of all the methods in the class.
New constructor
Create a new InvalidJsonType object (InvalidJsonType class)
This Constructor generates an instance of an InvalidGZipData exception. The New method format follows:
Syntax
%invalidJsonType = [%(InvalidJsonType):]New( Type= jsonType, MethodName= string)
Syntax terms
| %invalidJsonType | A reference to an instance of an InvalidJsonType object. |
|---|---|
| [%(InvalidJsonType):] | The class name in parentheses denotes a Constructor.. |
| jsonType | A JsonType enumeration value that indicates the underlying JSON type of the object to which the invalid method was applied. |
| string | The name of the method that encountered the error. |
Usage notes
- Json object tree can be created from data received from an outside data source that was generated via the Json Parse function. If the external data source is considered 100% in terms of sending JSON data with a known format, the data could be extracted without worries about InvalidJsonType exceptions. However, if there is a concern that the data will not be exactly what is expected, one should either test each object for the expected datatype via the Type function or wrap the data extraction inside a Try/Catch InvalidJsonType. Obviously, the latter requires less effort and is more efficient. For example, if an application expects an order to come in as an array of objects with a product name, code, quantity, and price but the source is not 100% trustworthy, one can do something like:
try for %i from 1 to %order:count %name = %order(%i)("name"):stringValue %code = %order(%i)("code"):stringValue %quantity = %order(%i)("quantity"):numberValue %price = %order(%i)("price"):numberValue ... process the order item end for catch invalidJsonType ... deal with the error end try
The Try/Catch adds no overhead to the processing but makes it easy to trap a malformed request.