Import/Export Routines
The following routines provide the ability to import and export objects to 4D BLOB variables. This allows you to easily save and restore objects either to the database or to files on disk.
OT BLOBToObject version 1
OT BLOBToObject(inBLOB {; ioOffset}) Longint
→
Parameter Type Description
inBLOB BLOB A BLOB which contains an object
→
ioOffset Longint The offset within the BLOB where
↔ the object can be found
Discussion
OT BLOBToObject retrieves an object from a BLOB into a new object handle. The Object must have been stored in the BLOB with OT ObjectToBLOB, not with VARIABLE TO BLOB.
If ioOffset is not passed in it defaults to zero.
If the bytes at the given offset do not describe an object stored with OT ObjectToBLOB, an error is generated, OK is set to zero, ioOffset is left untouched and a null handle (0) is returned.
Warning The handle returned is a new object that is added to ObjectTools’ internal list of objects. You must be sure to clear the new object with OT Clear when you no longer need it.
See Also
OT ObjectToBLOB, OT ObjectToNewBLOB
OT ObjectToBLOB version 1
OT ObjectToBLOB(inObject; ioBLOB {; inAppend})
Parameter Type Description
inObject Longint An object handle
→
ioBLOB BLOB A BLOB which receives the object
↔
inAppend Longint 0 to replace ioBLOB’s contents, non
→ zero to append to ioBLOB
Description
OT ObjectToBLOB stores an object into a BLOB. The previous contents of the BLOB, if any, are completely replaced, unless a non-zero value is passed in inAppend, in which case the object is appended to inBLOB.
Once stored within a BLOB, you must retrieve an object from a it with OT BLOBToObject, not with BLOB TO VARIABLE.
If inObject is not a valid object handle, if ioBLOB is not a valid BLOB, or if memory cannot be allocated to copy the object, an error is generated, OK is set to zero, and ioBLOB is cleared.
Warning Do not attempt to pass a BLOB field or a dereferenced pointer to a BLOB field in the ioBLOB paremeter, as this will result in a crash. If you want to retrieve a BLOB item into a field, either use an intermediate local variable or assign the result of OT ObjectToNewBLOB to the field.
The Object passed to OT ObjectToBLOB is copied into blob and remains in memory. You must be sure to clear it with OT Clear when you no longer need it.
See Also
OT BLOBToObject, OT ObjectToNewBLOB
OT ObjectToNewBLOB version 1.5
OT ObjectToNewBLOB(inObject) BLOB
→
Parameter Type Description
inObject Longint An object handle
→
Function result BLOB A new BLOB which contains the ↔ object
Description
OT ObjectToNewBLOB stores an object into a new BLOB.
Once stored within a BLOB, you must retrieve an object from a it with OT BLOBToObject, not with BLOB TO VARIABLE.
If inObject is not a valid object handle or if memory cannot be allocated to copy the object, an error is generated, OK is set to zero, and an empty BLOB is returned.
Warning The Object passed to OT ObjectToBLOB is copied into blob and remains in memory. You must be sure to clear it with OT IsObject when you no longer need it.
See Also