TnxDataset
Wed, 03/04/2009 - 20:02 | 
hdanzl
Declaration
TnxDataset = class(TDataSet)
Description
TnxDataset is the base class for all TDataset compatible Nexus components. Most methods and properties work exactly the same as Borland's implementation.
Events
The event is triggered if the FilterTimeout time has passed since activating a filter. Set cancel to false to give the server another FilterTimeout period of time to finish the filtering.
Methods
AddFileBlob adds a blob linked to real file. Please keep in mind that the file and it's name are server based and that NexusDB is not responsible for this file.
AddFileBlob adds a blob linked to real file. Please keep in mind that the file and it's name are server based and that NexusDB is not responsible for this file.
Only call BatchPost in batch append mode. It copies the current record buffer into the internal batch append buffer and posts the internal batch append buffer if its size is bigger than aCutoffSize defined in BeginBatchAppend.
Use BeginBatchAppend to start batch append mode. In this mode the only allowed actions are: setting field values, BatchPost, EndBatchAppend.
Please note that batch writing to blob fields is fully supported!
see TDataSet.BookmarkValid
see TDataSet.CompareBookmarks
The method copies all visible records from the source dataset to the current table.
It correctly uses the ranges/filters on the source table.
The method copies all visible records from the source dataset to the current table.
It correctly uses the ranges/filters on the source table.
constructor.
This function creates the right type of blob stream based on the state of the dataset.
The blob stream should be freed again as soon as possible. It must be freed before calling Post or moving to another record.
This method deletes all visible records of the current table. You can use filters/ranges to restrict the functionality to a subset of records.
Use this to delete the streams.
NEVER EVER DELETE THE DICT STREAM!
destructor.
This method terminates the batch append mode. It sends the internal batch append buffer to the server if required.
Exists returns true if this table exists, in the given session/database context.
It can be called without opening the table.
Only call in batch append mode. It forces the dataset to post the current internal batch append buffer.
GetAutoincValue gets the last used value of the AutoInc field of this dataset.
this function works even if there is no autoinc field declared in the table, because Nexus always tracks a "highest autoinc" value in the header.
see TDataSet.GetBookmark
see TDataSet.GetCurrentRecord
see TDataSet.GetFieldData
GetStreamList returns a list of the "table streams" saved in the table. A "table stream" is a delphi stream of system or user defined data that can be saved with a table. All tables contain a stream called DICT which contain the data dictionary.
GotoCurrent synchronizes a dataset with the given one or in other words positions the dataset on the same record as aDataSet. This method will result in an error if that record is currently not visible (range/filter) or if aDataSet is not positioned on a valid record
This function returns true if a Batch Append is open.
???
see TDataSet.IsSequenced
???
The text for this method has been generated automatically. This means that it is not documented.
see TDataSet.Locate
LockTable locks the dataset for the given operation. Make sure to keep these locks as short as possible, because it might otherwise interfere with the functionality/access of other instances to the table.
These locks interact directly with record locks, e.g. you can't acquire a table lock while anyone else has a record lock.
see TDataSet.Lookup
== virtual TDataSet methods == navigation
see TDataset.PSEndTransaction
see TDataset.PSExecuteStatement
see TDataset.PSGetQuoteChar
see TDataset.PSInTransaction
see TDataset.PSIsSQLBased
see TDataset.PSIsSQLSupported
see TDataset.PSReset
see TDataset.PSStartTransaction
Use this method to read a certain stream. It raises exception if not the stream is not found.
This method starts an asynchronous RecordCount. Very useful if there's for example a filter applied and the serves needs to iterate through all records to find out the count. Use TaskInfo.GetStatus to find out the status of the operation.
Use this method to set the AutoInc field's value; be very careful with this because it might break referential integrity based on these values and also might lead to posting errors due to unique field violations.
Remove the given lock from the dataset with this method.
UnlockTableAll releases all cursor based locks of this dataset, but this does not include record locks.
This method stores aStream in the table and overwrites any existing stream of that name.
NEVER EVER OVERWRITE THE DICT STREAM!
Properties
This is a pointer to the current cursor of this dataset.
Set ActiveDesigntime to true if the dataset should be automatically opened at design time. Very handy to use in combination with ActiveRuntime if you need the dataset open at design time, but sometimes forget to close it before creating a shipping version.
Set ActiveRuntime to true if the dataset should be automatically opened at runtime. Take care that this needs a fully set up chain of components otherwise you very likely get an "could not connect to server" error on application startup.
see TDataSet.AfterCancel.
see TDataSet.AfterClose.
see TDataSet.AfterDelete
see TDataSet.AfterEdit
see TDataSet.AfterInsert
see TDataSet.AfterOpen
see TDataSet.AfterPost
see TDataSet.AfterRefresh
see TDataSet.AfterScroll
AliasName is a quick way to access an alias without a connected tnxDatabase. AliasName does NOT support direct paths!
Please not that Session must be assigned for this to work.
see TDataSet.AutoCalcFields
see TDataSet.BeforeCancel
see TDataSet.BeforeClose
see TDataSet.BeforeDelete
see TDataSet.BeforeEdit
see TDataSet.BeforeInsert
see TDataSet.BeforeOpen
see TDataSet.BeforePost
see TDataSet.BeforeRefresh
see TDataSet.BeforeScroll
Use BlockReadOptions to set how block/batch operations work.
If gboBookmarks is true, bookmarks are received from the server as well as records. The Borland's implementation in TTable doesn't support bookmarks during batch reads.
If gboBlob is true, blobs are processed in the batch modes.
This is database the dataset is linked to. Either AliasName or Database must be set.
The Dictionary holds all field and index definitions as well as full information on how to access and read the data file.
The text for this property has been generated automatically. This means that it is not documented.
see TDataset.Filter
see TDataset.Filtered
see TDataset.FilterOptions
This is the timeout in ms for Filter operations.
The text for this property has been generated automatically. This means that it is not documented.
see TDataSet.OnCalcFields
see TDataSet.OnDeleteError
see TDataSet.OnEditError
see TDataSet.OnFilterRecord
see TDataSet.OnNewRecord
see TDataSet.OnPostError
The text for this property has been generated automatically. This means that it is not documented.
This is the session the dataset is linked to. You only need to set this if you want to use AliasName, otherwise (when using an explicit database component) it is automatically set internally.
the Filter class the dataset creates an instance of for each Filter evaluation set
the Filter class the dataset creates an instance of for each Filter evaluation set
The is the timeout in ms used for communication with the server. If it -1 the timeout is inherited from Database.
The text for this property has been generated automatically. This means that it is not documented.
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