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DataField Class

Create a field, which is an object that holds information that defines a particular field in a data server (for example, the field's data type and length).
Inheritance Hierarchy

Namespace:  VO
Assembly:  VOSystemClasses (in VOSystemClasses.dll) Version: 2.16
 CLASS DataField
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The DataField type exposes the following members.

Public methodDataField
Construct a data field.
Public propertyFieldSpec
The FieldSpec object connected to this field.
Public propertyHyperLabel
The hyperlabel connected to this field.
Public propertyName
A string representing the name of the field.
Public propertyNameSym
A symbol representing the name of the field.
Public methodAsString
Return the descriptive label defined for this field.
A DataField object is a specific item in a database record. This is in contrast to a FieldSpec object, which is a description of the properties that some field might have. For example, assume you want to create a FieldSpec object that defines an employee number and you have an EMPLOYEE database that has two different fields: EMPNO, which the employee's number (the employee whose record this is), and MGRNO, which is the number of that employee's manager. Thus, you might define the FieldSpec object as follows:
1CLASS EmployeeNumber INHERIT FieldSpec
and then in the database define two different fields as:
1DataField{HyperLabel{#EmpNo, "Employee Number"}, ;
3DataField{HyperLabel{#MgrNo, "Manager Number"}, ;
Note that some of the field properties can appear redundant given the available FieldSpec properties. For example, the field contains a hyperlabel, but the field's FieldSpec object also contains a hyperlabel. Furthermore, the field's hyperlabel contains a symbolic name, and the FieldSpec's hyperlabel contains a symbolic name. However, this apparent redundancy serves a useful purpose. A FieldSpec's hyperlabel identifies the general class of data (called #EmpNo in this example). This name is often used as the standard name of fields of this type, but it does not have to be, because each particular field has a specific name — in the example above, #EmpNo and #MgrNo. A field, therefore, holds two "groups" of properties: General label information, like its name, caption, description, and help context ID Data type information, stored as a FieldSpec object, that includes data type, length, decimals, validation rules, error messages, diagnostics, and formatting rules In any case, all data-oriented objects in the system have a name and a hyperlabel, which are often shipped around the system for annotation and help purposes.
Important! There is rarely a need for the developer to consider the fields directly as they are typically created through the code generated by the various data server editors.
See Also