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C H A P T E R 1 1
Data Storage and Retrieval
Using Newton Data Storage Objects
11-57
Note that if the query used to generate the cursor specifies a
beginKey
value, the
CountEntries
method starts counting at the first valid entry having an index key
value equal to or greater than the
beginKey
value. Similarly, if the query that
generated the cursor used an
endKey
value, the
CountEntries
method stops
counting at the last valid entry having an index key value equal to or less than the
endKey
value.
Note that the use of the
CountEntries
method is somewhat time-consuming and
may increase your application's heap space requirements; for performance reasons,
use this method only when necessary.
Getting the Current Entry's Index Key
11
The
EntryKey
cursor method returns the index key data associated with the
current cursor entry without reading the entry into the NewtonScript heap. Note,
however, that under certain circumstances the value returned by this method does
not match the entry's index key data exactly. For more information, see "Limitations
of Index Keys" on page 11-52.
Copying Cursors
11
You can clone a cursor to use for browsing soup entries without disturbing the
original cursor. Do not use the global functions
Clone
or
DeepClone
to clone
cursors. Instead, use the
Clone
method of the cursor to be copied, as shown in the
following code fragment:
local namesUSoup:= GetUnionSoupAlways(ROM_CardFileSoupName);
local namesCursor := namesUSoup:Query(nil);
local cursorCopy:= namesCursor:Clone();
Using Entries
11
This section discusses the functions and methods that work with soup entry objects
returned by cursors. This section describes
adding entries to soups
removing entries from soups
saving references to entries
modifying entries
replacing entries
sharing entry data
copying entry data
using the entry cache effectively
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