Midware TMWTable

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Overview

unit

MWdatSet.pas

TMWTable component is much like standard Delphi TTable or TQuery components. TMWTable is used as an interface between data and your program or visual interface.

TMWTable is a TDataSet descendent so you can use it with data-aware controls such as TDBEdit and TDBGrid. Just like you use TQuery or TTable.

TMWTable is an interface that present MidWare communication buffer (TMWBuffer component) as a standard Delphi data table. It let you navigate thru all records and fields. You can and locate data, insert, delete or edit data. TMWTable has no storage for data: all data is stored in TMWBuffer component.

TMWTable has no knowledge of table structure. You must specify it using FieldLayout property. You can fill this property at design time if you know what it will be at runtime, or you may fill it at runtime once you know the value. The value may be known at runtime because your client application query the application server for field layout. You may also sent field layout in first record in result set, feed it to the property and then delete it from result set.

Properties

Active		Active property is TRUE when TMWTable is opened and FALSE when TMWTable is closed.
AppSrvClient		To execute a request at design time, TMWTable need an TAppSrvClient component which will handle communication with MidWare application server.
AutoCalcFields		Set AutoCalcFields to control when the OnCalcFields event is triggered to update calculated fields during dataset processing.
CanModify		CanModify readonly property returns TMWTable ReadOnly value.
Data		Data property is a link to TMWBuffer component used to hold all data.
FieldLayout		FieldLayout property is used to describe columns content.
FunctionCode		FunctionCode and Params properties are the design time request. It's main purpose is to populate data aware controls link to TMWTable at design time. It can also be executed at runtime using ExecuteRequest.
MWBufferFieldCount		The number of fields. Based on FieldLayout property.
ReadOnly		ReadOnly property is used to get or set TMWtable read only status. See also CanModify.
RecordSize		The record size property gives the size of the record.
Params		FunctionCode and Params properties are the design time request.
TimeOut		When executing a request at design time, TMWTable will stop waiting for answer after Timeout seconds.

Methods

Close		Close the communication with the application server.
CreateBlobStream		Call CreateBlobStream to obtain a stream for reading and writing the value of the field specified by the Field parameter.
DesignTimeRequest		DesignTimeRequest procedure will execute the request specified at design time.
ExecuteRequest		Call ExecuteRequest procedure to execute design time request.
Locate		Implements a method for searching a dataset for a specified record and makes that record the current record.
Lookup		Implements a method to retrieve field values from a record that matches specified search values.
Send		Send a FunctionCode and Request (parmeters) to the application server.

Events

AfterCancel		Occurs after an application completes a request to cancel modifications to the current record.
AfterClose		Occurs after an application closes a dataset.
AfterDelete		Occurs after an application deletes a record.
AfterEdit		Occurs after an application starts editing a record.
AfterInsert		Occurs after an application inserts a new record.
AfterOpen		Occurs after an application completes opening a dataset and before any data access occurs.
AfterScroll		Occurs after an application scrolls from one record to another.
BeforeCancel		Write a BeforeCancel event to take specific action before an application carries out a request to cancel changes.
BeforeClose		Write a BeforeClose event to take specific action before an application closes a dataset.
BeforeDelete		Write a BeforeDelete event handler to take specific action before an application deletes the current record.
BeforeEdit		Write a BeforeEdit event handler to take specific action before an application enables editing of the current record.
BeforeInsert		Write a BeforeInsert event handler to take specific action before an application inserts or appends a new record.
BeforeOpen		Write an AfterOpen event handler to take specific action immediately after an application opens the dataset.
BeforeScroll		Write a BeforeScroll event handler to take specific action immediately after an application scrolls to another record as a result of a call to the First, Last, MoveBy, Next, Prior, FindKey, FindFirst, FindNext, FindLast, FindPrior, and Locate methods.
OnCalcField		Write an OnCalcFields event handler to take specific action when an application recalculates calculated fields.
OnDisplayInfo		This is used for debugging purpose and should normally not be used in an application.
OnDeleteError		Write an OnDeleteError event handler to handle exceptions that occur when an attempt to delete a record fails.
OnEditError		Write a BeforeEdit event handler to take specific action before an application enables editing of the current record.
OnNewRecord		Write an OnNewRecord event handler to take specific actions as an application inserts or appends a new record.
OnPostError		Write an OnPostError event handler to handle exceptions that occur when an attempt to edit a record fails.
OnRequestDone		When design time request has been executed, then event OnRequestDone is triggered.

How To

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Midware Components Reference