Data Dictionary
From jVantage
jVantage employs a data dictionary for all of its field definitions. This means that rather than specifying the fields of your application in terms of primitive field descriptors such as how long the field is or whether it can contain numbers or letters or both; field types are created that specify this information but also provide logic for content validation. For example, if you create an entity type for a contact in a contact management application; rather than specifying an e-mail field as a simple input field that can hold up to 60 characters, you instead create a new dictionary type called e-mail. This e-mail type would be defined as an alphanumeric type with a length of 60 characters. But, in addition, regular expressions could be defined that examine data that is entered into this field, anywhere it appears in any of your applications, thus verifying that only valid e-mail addresses can be entered.
Data dictionary types are very powerful. Not only can zero or more regular expressions be associated with each dictionary type, help text can also be associated with the regular expressions to provide assistance to your users if they enter invalid data into the associated field.
jVantage also provides a regular expression tester that allows regular expressions to be keyed in and tested against different data sets so you can verify that your regular expressions work the way you want them to prior to employing them in your applications. The regular expression tester can be accessed using the relationship menu when viewing any data dictionary type definition.
Regular expressions are not the only validators that can be associated with data dictionary types. jVantage also supports valid value and invalid value enumerations for each dictionary type. This is useful in cases where a known set of valid entries applies to a given type. For instance, if you were to create an application that collected the favorite color of your users, you can create a a dictionary type called color and the fine a set of valid values that contained only the colors that you would like the users to choose from. What valid value or in valid value enumerations are defined for dictionary type, the field and put is rendered as a pulldown choice list on all input forms where fields of the color type are used.
The database metadata view displays the database product name, the driver being used communicate with the database, as well as other relevant information about the specific table entity that you are viewing. This page is mostly for informational purposes, however, it does contain one vital piece of functionality – it allows you to create unique indexes. This is important in cases where you want to prevent duplicate entries in your data set.
Invalid value enumerations are the opposite of valid value enumerations. Invalid enumerations allow you to specify values for dictionary types that are not acceptable for the associated field.
