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CeReadRecordProps (RAPI) (Windows Embedded CE 6.0)

  • Статья

1/6/2010

This function reads properties from the current record of a database on a remote Windows Embedded CE–based device.

Note

This method has been deprecated. Use CeReadRecordPropsEx instead.

Syntax

CEOID CeReadRecordProps(
  HANDLE hDbase, 
  DWORD dwFlags, 
  LPWORD lpcPropID, 
  CEPROPID * rgPropID, 
  LPBYTE * lplpBuffer, 
  LPDWORD lpcbBuffer 
);

Parameters

  • hDbase
    [in] Handle to an open database. The database must have been opened by a previous call to the CeOpenDatabase function.

  • dwFlags
    [in] Specifies a bitmask of read flags. It is the following value.

    Value Description

    CEDB_ALLOWREALLOC

    The LocalAlloc function was used to allocate the buffer specified by the lplpBuffer parameter, and the server can reallocate the buffer if it is not large enough to hold the requested properties.
  • lpcPropID
    [in,out] Pointer to the number of property identifiers in the array specified by the rgPropID parameter. If rgPropID is NULL, this parameter receives the number of properties retrieved.
  • rgPropID
    [in] Pointer to an array of property identifiers for the properties to be retrieved. If this parameter is NULL, CeReadRecordProps retrieves all properties in the record.
  • lplpBuffer
    [out] Pointer to a long pointer to a buffer that receives the requested properties. If the dwFlags parameter includes the CEDB_ALLOWREALLOC flag, the buffer may be reallocated if necessary. If the CEDB_ALLOWREALLOC flag is specified and this parameter is NULL, the server uses the LocalAlloc function to allocate a buffer of the appropriate size in the caller's address space and returns a pointer to the buffer. Note that if the CEDB_ALLOWREALLOC flag is specified, it is possible for the value of this pointer to change even on failure. For example, the old memory might be freed and the allocation might then fail, leaving the pointer set to NULL.
  • lpcbBuffer
    [out] Long pointer to a variable that contains the size, in bytes, of the buffer specified by the lplpBuffer parameter. When CeReadRecordProps returns, lpcbBuffer receives a value that indicates the actual size of the data copied to the buffer. If the buffer was too small to contain the data, this parameter can be used to calculate the amount of memory to allocate for the buffer if CEDB_ALLOWREALLOC was not specified.

Return Value

The object identifier of the record from which the function read indicates success. Zero indicates failure. To get extended error information, call CeGetLastError and CeRapiGetError. Possible values for CeGetLastError include the following:

  • ERROR_INVALID_PARAMETER
    A parameter was invalid.
  • ERROR_NO_DATA
    None of the requested properties was found. The output buffer and the size are valid.
  • ERROR_INSUFFICIENT_BUFFER
    The specified buffer was not large enough, and the reallocation failed — if the CEDB_ALLOWREALLOC flag was specified. The lpcbBuffer parameter contains the required buffer size.
  • ERROR_KEY_DELETED
    The record that was about to be read was deleted by another thread. If the current record was reached as a result of an autoseek, this error is not returned, and the next record is returned.
  • ERROR_NO_MORE_ITEMS
    The current seek pointer is at the end of the database.

Remarks

The CeReadRecordProps function reads the specified set of properties from the current record. If the database was opened with the autoseek flag — that is, if the dwFlags parameter of CeOpenDatabase was set to CEDB_AUTOINCREMENT — then CeReadRecordProps increments the seek pointer by one so that the next call reads the next record in the current sort order. That is, if the database was opened with a sort order active, then CeReadRecordProps will return the records in sorted order. If the database was not opened with a sort order active, then the order in which records are returned is not predictable.

Read all needed properties from the record in a single call. The entire record is stored in a compressed format, and each time a property is read it must be decompressed. All the properties are returned in a single marshaled structure, which consists of an array of CEPROPVAL structures, one for each property requested — or one for each property found if the application set the rgPropID parameter to NULL when calling the function.

When you are done reading properties, you need to free the memory used by the lplpBuffer buffer with a call to CeRapiFreeBuffer.

If a property was requested, such as strings or binary large objects (BLOBs) that are packed in at the end of the array, the pointers in the CEPROPVAL structures point into this marshaled structure. This means that the only memory that must be freed is the original pointer to the buffer passed in to the call. Even if the function fails, it may have allocated memory on the caller's behalf. Free the pointer returned by this function if the pointer is not NULL.

Note

Earlier versions of Windows Embedded CE assigned object identifiers to objects in other file systems, such as the file allocation table (FAT) file system. These object identifiers were guaranteed to be unique within a volume, but not across multiple volumes. Effective with version 3.0, only objects in the object store have valid, unique object identifiers, and the object store is the only volume that can return an object identifier.

Requirements

Header rapi.h
Library rapi.lib
Windows Embedded CE Windows CE 3.0 and later

See Also

Reference

RAPI Functions
CeOpenDatabase (RAPI)
CeSeekDatabase (RAPI)
CEPROPVAL