Defining Class Methods in Data Type Classes

Depending on your needs, you should define some or all of the following class methods in your data type classes:

IsValid() — performs validation of data for the property, using property parameters if appropriate. As noted earlier, the %ValidateObject() instance method of any object class invokes the IsValid() method for each property. This method has the following signature:
```
ClassMethod IsValid(%val) As %Status 
```
Where %val is the value to be validated. This method should return an error status if the value is invalid and should otherwise return $$$OK.

Note:

It is standard practice in InterSystems IRIS not to invoke validation logic for null values.
Normalize() — converts the data for the property into a standard form or format. The %NormalizeObject() instance method of any object class invokes the Normalize() method for each property. This method has the following signature:
```
ClassMethod Normalize(%val) As Type 
```
Where %val is the value to be validated and Type is a suitable type class.
DisplayToLogical() — converts a display value into a logical value. (For information on formats, see Data Formats.) This method has the following signature:
```
ClassMethod DisplayToLogical(%val) As Type 
```
Where %val is the value to be converted and Type is a suitable type class.
The other format conversion methods have the same general form.
LogicalToDisplay() — converts a logical value to a display value.
LogicalToOdbc() — converts a logical value into an ODBC value.
Note that the ODBC value must be consistent with the ODBC type specified by the OdbcType class keyword of the data type class.
LogicalToStorage() — converts a logical value into a storage value.
LogicalToXSD() — converts a logical value into the appropriate SOAP-encoded value.
OdbcToLogical() — converts an ODBC value into a logical value.
StorageToLogical() — converts a database storage value into a logical value.
XSDToLogical() — converts a SOAP-encoded value into a logical value.

Important:

All these methods are class methods and all of them must accept an argument: the value to check for validity, to normalize, to convert, and so on.

If the data type class includes the DISPLAYLIST and VALUELIST parameters, these methods must first check for the presence of these class parameters and include code to process these lists if present. The logic is similar for other methods.

In most cases, many of these methods are method generators.

Note:

Note that the data format and translation methods cannot include embedded SQL. If you need to call embedded SQL within this logic, then you can place the embedded SQL in a separate routine, and the method can call this routine.

Defining Instance Methods in Data Type Classes

Defining a Data Type Class