FieldSpec Class

Create a field specification, which holds general data type information about data elements, such as database fields and window controls.

Inheritance Hierarchy

Object
  FieldSpec
    DateFS
    IntegerFS
    LogicFS
    NumberFS
    StringFS

Namespace: VO
Assembly: VOSystemClasses (in VOSystemClasses.dll) Version: 2.19

Syntax

Copy

 CLASS FieldSpec

public class FieldSpec

Request Example View Source

The FieldSpec type exposes the following members.

Constructors

	Name	Description
	FieldSpec	Construct a field specification.

Top

Properties

	Name	Description
	Decimals	A numeric value representing the number of decimals defined to this field specification.
	HyperLabel	The hyperlabel connected to this field specification.
	Length	A numeric value representing the length defined to this field specification.
	Maximum	A numeric value representing the maximum value in the range validation for this field specification.
	Minimum	A numeric value representing the minimum value in the range validation for this field specification.
	MinLength	A numeric value representing the new minimum length validation for this field specification.
	MinLengthHL	Error message when MinLength validation fails.
	Nullable	Is the field Nullable ?
	Picture	A string representing the picture clause defined to this field specification. It is used by the FieldSpec:Transform() method.
	RangeHL	Error message when Range validation fails.
	Required	Logical value indicating whether the field is required (TRUE) or not (FALSE).
	RequiredHL	Error message when Required validation fails.
	Status	After a validation request (see FieldSpec:PerformValidations() for details), this contains a HyperLabel object that describes the results of the validation or NULL_OBJECT if the validation passed.
	UsualType	A constant, representing the data type defined to this field specification:
	Validation	A code block that sets the validation rule for this field specification.
	ValidationHL	Error message when Validation fails.
	ValType	A one-character string representing the data type defined to this field specification:

Top

Methods

	Name	Description
	AsString	Return the caption defined to this field specification's hyperlabel; if no caption is defined, return the name defined to the hyperlabel.
	PerformValidations	Test a specified value to see if it passes all of this field specification's validation rules.
	SetLength	Set a new length for this field specification and new hyperlabel diagnostics for the length check.
	SetMinLength	Set a new minimum length validation for this field specification and new hyperlabel diagnostics for the minimum length check.
	SetRange	Set a new range validation for this field specification and new hyperlabel diagnostics for the range check.
	SetRequired	Set a new required validation for this field specification and new hyperlabel diagnostics for the required check.
	SetType	Set a new data type for this field specification and new hyperlabel diagnostics for the data type check.
	SetValidation	Set a new validation rule for this field specification and new hyperlabel diagnostics for the validation rule check.
	Transform	Convert a specified value into a string, formatted according to this field specification's picture clause.
	Val	Convert a string to a value, according to this field specification's defined data type.
	Validate	A replaceable method for performing validations. The standard implementation evaluates the code block specified through FieldSpec:SetValidation().

Top

Remarks

A FieldSpec object holds a number of properties which relate to fields. Specifically, a FieldSpec object can be defined for: Because both types ultimately apply to fields, a field specification's properties are described in terms of fields only (i.e., not window controls).

Tip
A field specification corresponds to what is sometimes referred to as an "element definition," a "domain," or an "abstract data type."

The field specification holds the following properties:

Property	Description
Decimals	The number of decimals in a field (numeric only)
Diagnostics	Hyperlabels for each of the validation rules. Note that a hyperlabel contains not only a diagnostic message, but also a help context to provide for context sensitive help after a validation failure.
HyperLabel	Information about a field: its name, caption, description, and help context
Length	The length of a field
Min,Max	The data range allowed in a field
MinLength	The minimum number of characters allowed in a field (for example, a STATE field can be defined with a Length and MinLength of 2, while a PASSWORD might have a Length of 10 and a MinLength of 4)
Picture	A picture clause used to format a field. This is a standard Xbase picture clause, such as @! or 999-99-9999.
Status	A HyperLabel object that describes the results of a validation test (it is NIL if the validation passed)
Type	The underlying storage type of a field (number, string, logic, date, or memo)
Validation	A code block that sets validation rule to be used for a field (i.e., required fields, data type compliance, range compliance, and so on) Also note that a FieldSpec subclass can be given a Validation() method, which overrides this code block.

Reference

VO Namespace