TDAConstantExpression

Overview

The TDAConstantExpression is a descendant of the TDAWhereExpression and represents a constant in an expression.

Location

 

constructor Create (Variant)  overload

Creates a new expression with a supplied aValue.

constructor Create(const aValue: Variant)

Parameters:

  • aValue: Value of the constant.

constructor Create (Variant, TDADataType)  overload

Creates a new expression with a supplied aValue and aType.

constructor Create(const aValue: Variant; aType: TDADataType)

Parameters:

  • aValue: Value of the constant.
  • aType: Data type of the constant.

aType

Data type of the constant represented in the TDAConstantExpression.

property aType: TDADataType read write

DeserializeObject

Gets the object of the given TDAConstantExpression from the serialized string.

class function DeserializeObject(const s: UnicodeString; dt: TDADataType): Variant

Parameters:

  • s: string
  • dt: datatype

DoValidate  protected    (declared in TDAWhereExpression)

Raised exception if aRaiseException is set

procedure DoValidate(aRaiseException: Boolean; aName: string)

Parameters:

  • aRaiseException: specifies should the exception be raised or not.
  • aName: Name of property

GetWhereKind  protected override

function GetWhereKind: TDAWhereKind

Kind    (declared in TDAWhereExpression)

property Kind: TDAWhereKind read

ParseException  protected    (declared in TDAWhereExpression)

Raises EDAWhereParseXmlException.

procedure ParseException(aName: string)

Parameters:

  • aName: property name.

ParseExpression (IXmlNode, string): TDAWhereExpression  protected overload    (declared in TDAWhereExpression)

Calls ParseException if xr is nil, otherwise calls overload ParseException.

function ParseExpression(xr: IXmlNode; aName: string): TDAWhereExpression

Parameters:

  • xr: source node.
  • aName: Name of property

ParseExpression (IXmlNode): TDAWhereExpression  overload    (declared in TDAWhereExpression)

Creates new Where expression from XML node.

class function ParseExpression(xr: IXmlNode): TDAWhereExpression

Parameters:

  • xr: given XML node.

ReadFromXml  override

Reads where expression from the XML.

procedure ReadFromXml(xr: IXmlNode)

Parameters:

  • xr: source node

RemoveEmptyNodes    (declared in TDAWhereExpression)

class procedure RemoveEmptyNodes(aNode: IXMLNode)

Parameters:

  • aNode:

SerializeObject

Writes the object of the given type to the string.

class function SerializeObject(const v: Variant; dt: TDADataType): UnicodeString

Parameters:

  • v: value
  • dt: datatype

Validate  virtual    (declared in TDAWhereExpression)

Validates properties of expression.

procedure Validate

Value

Value of the constant represented in the TDAConstantExpression.

property Value: Variant read write

WriteToXml  override

Writes where expression to the XML.

procedure WriteToXml(sw: IXmlNode)

Parameters:

  • sw: destination node

 

aType

Data type of the constant represented in the TDAConstantExpression.

property aType: TDADataType read write

Kind    (declared in TDAWhereExpression)

property Kind: TDAWhereKind read

Value

Value of the constant represented in the TDAConstantExpression.

property Value: Variant read write

 

DeserializeObject

Gets the object of the given TDAConstantExpression from the serialized string.

class function DeserializeObject(const s: UnicodeString; dt: TDADataType): Variant

Parameters:

  • s: string
  • dt: datatype

ParseExpression (IXmlNode): TDAWhereExpression  overload    (declared in TDAWhereExpression)

Creates new Where expression from XML node.

class function ParseExpression(xr: IXmlNode): TDAWhereExpression

Parameters:

  • xr: given XML node.

RemoveEmptyNodes    (declared in TDAWhereExpression)

class procedure RemoveEmptyNodes(aNode: IXMLNode)

Parameters:

  • aNode:

SerializeObject

Writes the object of the given type to the string.

class function SerializeObject(const v: Variant; dt: TDADataType): UnicodeString

Parameters:

  • v: value
  • dt: datatype

 

constructor Create (Variant)  overload

Creates a new expression with a supplied aValue.

constructor Create(const aValue: Variant)

Parameters:

  • aValue: Value of the constant.

constructor Create (Variant, TDADataType)  overload

Creates a new expression with a supplied aValue and aType.

constructor Create(const aValue: Variant; aType: TDADataType)

Parameters:

  • aValue: Value of the constant.
  • aType: Data type of the constant.

DoValidate  protected    (declared in TDAWhereExpression)

Raised exception if aRaiseException is set

procedure DoValidate(aRaiseException: Boolean; aName: string)

Parameters:

  • aRaiseException: specifies should the exception be raised or not.
  • aName: Name of property

GetWhereKind  protected override

function GetWhereKind: TDAWhereKind

ParseException  protected    (declared in TDAWhereExpression)

Raises EDAWhereParseXmlException.

procedure ParseException(aName: string)

Parameters:

  • aName: property name.

ParseExpression (IXmlNode, string): TDAWhereExpression  protected overload    (declared in TDAWhereExpression)

Calls ParseException if xr is nil, otherwise calls overload ParseException.

function ParseExpression(xr: IXmlNode; aName: string): TDAWhereExpression

Parameters:

  • xr: source node.
  • aName: Name of property

ReadFromXml  override

Reads where expression from the XML.

procedure ReadFromXml(xr: IXmlNode)

Parameters:

  • xr: source node

Validate  virtual    (declared in TDAWhereExpression)

Validates properties of expression.

procedure Validate

WriteToXml  override

Writes where expression to the XML.

procedure WriteToXml(sw: IXmlNode)

Parameters:

  • sw: destination node