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Implements a data packet reader using binary data packets
Source position: bufdataset.pas line 415
type TFpcBinaryDatapacketReader = class(TDataPacketReader) |
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public |
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constructor Create(); override; |
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Constructor for the class instance |
procedure LoadFieldDefs(); override; |
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Loads field definitions using the data packet reader |
procedure StoreFieldDefs(); override; |
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Stores field definitions using the data packet reader |
procedure InitLoadRecords; override; |
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function GetCurrentRecord; override; |
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function GetRecordRowState(); override; |
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procedure RestoreRecord; override; |
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procedure GotoNextRecord; override; |
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procedure StoreRecord(); override; |
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procedure FinalizeStoreRecords; override; |
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class function RecognizeStream(); override; |
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end; |
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Implements a data packet reader using binary data packets |
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Implements a data packet reader for TBufDataset |
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TFpcBinaryDatapacketReader is a TDatapacketReader descendant that implements a data packet reader using binary data packets. Binary data packets use the following layout:
| Section | Name | Length | Description |
| Header | Identification | 13 bytes | Contains the value 'BinBufDataSet' |
| Version | 1 byte | Version number | |
| Field Definition Count | 2 bytes | Column Layout for field definition values | |
| Field Definitions | Field Name Length | 2 bytes | Section occurs the number of times indicated in Field Definition Count |
| Field Name | See above | Name of the field in the dataset | |
| Display Name Length | 2 bytes | ||
| Display Name | See above | Caption for the field | |
| Data Type | 2 bytes | ||
| Read-Only Attribute | 1 byte | 0=read/write, 1=read-only | |
| Parameters | AutoInc Value | 4 bytes | Integer value for the auto-increment field type |
| Row Header | Row Marker | 1 byte | Contains the value $fe |
| Row State | 1 byte | 0=original, 1=deleted, 2=inserted, 3=modified | |
| Update Order | 4 bytes | ||
| Null Bitmap | Variable length. | 1 byte required for eight fields; 2 bytes for 16 fields, etc. See Field Definition Count. Bit values are set to 1 when the corresponding field is null. | |
| Row Data | Optional Field Length | 4 bytes | Variable-length fields are prefixed with their length. Fixed-length fields do not require this entry. Null fields are not stored. |
| Field Data | Bytes values for the field. See Optional Field Length. | Occurs the number of times needed for Field Definition Count. |
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Implements a data packet reader for TBufDataset |