FileAccess DataFlex Reference Documentation

FileAccess

API for reading and writing files, creating and deleting directories, deleting directory trees, splitting and re-joining large files, etc. This is a freeware class. The reason for its existence is that in some programming languages, file I/O API's are limited or difficult to understand/use. This API provides an identical FILE I/O API across all programming languages supported by Chilkat.

Object Creation

Handle hoFileAccess
Get Create(RefClass(cComCkFileAccess)) to hoFileAccess

Properties

Function ComCurrentDir Returns String

The current working directory of the calling process.

Function ComDebugLogFilePath Returns String
Procedure Set ComDebugLogFilePath String value

If set to a file path, causes each Chilkat method or property call to automatically append it's LastErrorText to the specified log file. The information is appended such that if a hang or crash occurs, it is possible to see the context in which the problem occurred, as well as a history of all Chilkat calls up to the point of the problem. The VerboseLogging property can be set to provide more detailed information.

This property is typically used for debugging the rare cases where a Chilkat method call hangs or generates an exception that halts program execution (i.e. crashes). A hang or crash should generally never happen. The typical causes of a hang are:

  1. a timeout related property was set to 0 to explicitly indicate that an infinite timeout is desired,
  2. the hang is actually a hang within an event callback (i.e. it is a hang within the application code), or
  3. there is an internal problem (bug) in the Chilkat code that causes the hang.

Function ComEndOfFile Returns Boolean

Returns True if the current open file is at the end-of-file.

Function ComFileOpenError Returns Integer

This property is set by the following methods: FileOpen, OpenForRead, OpenForWrite, OpenForReadWrite, and OpenForAppend. It provides an error code indicating the failure reason. Possible values are:

  1. Success (No error)
  2. Access denied.
  3. File not found.
  4. General (non-specific) open error.
  5. File aleady exists.
  6. Path refers to a directory and the access requested involves writing.
  7. Too many symbolic links were encountered in resolving path.
  8. The process already has the maximum number of files open.
  9. Pathname is too long.
  10. The system limit on the total number of open files has been reached.
  11. Pathname refers to a device special file and no corresponding device exists.
  12. Insufficient kernel memory was available.
  13. Pathname was to be created but the device containing pathname has no room for the new file.
  14. A component used as a directory in pathname is not, in fact, a directory.
  15. Pathname refers to a regular file, too large to be opened (this would be a limitation of the underlying operating system, not a limitation imposed by Chilkat).
  16. Pathname refers to a file on a read-only filesystem and write access was requested.

Function ComFileOpenErrorMsg Returns String

The error message text associated with the FileOpenError code.

Function ComLastBinaryResult Returns Variant

Introduced in version 9.5.0.52

The binary data returned by the last (binary data returning) method called. Only available if Chilkat.Global.KeepBinaryResult is set to True. This provides a means for obtaining large varbinary results in the SQL Server environment (where limitations exist in getting large amounts of data returned by method calls, but where temp tables can be used for binary properties).

Function ComLastErrorHtml Returns String

Provides information in HTML format about the last method/property called. If a method call returns a value indicating failure, or behaves unexpectedly, examine this property to get more information.

Function ComLastErrorText Returns String

Provides information in plain-text format about the last method/property called. If a method call returns a value indicating failure, or behaves unexpectedly, examine this property to get more information.

Concept of LastErrorText

LastErrorText Standard Information

Function ComLastErrorXml Returns String

Provides information in XML format about the last method/property called. If a method call returns a value indicating failure, or behaves unexpectedly, examine this property to get more information.

Function ComLastMethodSuccess Returns Boolean
Procedure Set ComLastMethodSuccess Boolean value

Introduced in version 9.5.0.52

Indicate whether the last method call succeeded or failed. A value of True indicates success, a value of False indicates failure. This property is automatically set for method calls. It is not modified by property accesses. The property is automatically set to indicate success for the following types of method calls:

  • Any method that returns a string.
  • Any method returning a Chilkat object, binary bytes, or a date/time.
  • Any method returning a standard boolean status value where success = True and failure = False.
  • Any method returning an integer where failure is defined by a return value less than zero.

Note: Methods that do not fit the above requirements will always set this property equal to True. For example, a method that returns no value (such as a "void" in C++) will technically always succeed.

Function ComLastStringResult Returns String

Introduced in version 9.5.0.52

The string return value of the last (string returning) method called. Only available if Chilkat.Global.KeepStringResult is set to True. This provides a means for obtaining large string results in the SQL Server environment (where limitations exist in getting long strings returned by method calls, but where temp tables can be used for string properties).

Long Strings Returned by ActiveX Methods in SQL Server

Function ComLastStringResultLen Returns Integer

Introduced in version 9.5.0.53

The length, in characters, of the string contained in the LastStringResult property.

Function ComVerboseLogging Returns Boolean
Procedure Set ComVerboseLogging Boolean value

If set to True, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. The default value is False. Verbose logging should only be used for debugging. The potentially large quantity of logged information may adversely affect peformance.

Function ComVersion Returns String

Version of the component/library, such as "9.5.0.63"

Methods

Function ComAppendAnsi String text Returns Boolean

Appends a string using the ANSI character encoding to the currently open file.

Returns True for success, False for failure.

Function ComAppendText String str String charset Returns Boolean

Appends a string using the character encoding specified by str to the currently open file.

Returns True for success, False for failure.

Function ComAppendUnicodeBOM Returns Boolean

Appends the 2-byte Unicode BOM (little endian) to the currently open file.

Returns True for success, False for failure.

Function ComAppendUtf8BOM Returns Boolean

Appends the 3-byte utf-8 BOM to the currently open file.

Returns True for success, False for failure.

Function ComDirAutoCreate String filePath Returns Boolean

Same as DirEnsureExists, except the argument is a file path (the last part of the path is a filename and not a directory). Creates all missing directories such that filePath may be created.

Returns True for success, False for failure.

Function ComDirCreate String dirPath Returns Boolean

Creates a new directory specified by dirPath.

Returns True for success, False for failure.

Function ComDirDelete String dirPath Returns Boolean

Deletes the directory specified by dirPath.

Returns True for success, False for failure.

Function ComDirEnsureExists String dirPath Returns Boolean

Creates all directories necessary such that the entire dirPath exists.

Returns True for success, False for failure.

Procedure ComFileClose

Closes the currently open file.

Function ComFileContentsEqual String filePath1 String filePath2 Returns Boolean

Compares the contents of two files and returns True if they are equal and otherwise returns False. The actual contents of the files are only compared if the sizes are equal. The files are not entirely loaded into memory. Instead, they are compared chunk by chunk. This allows for any size files to be compared, regardless of the memory capacity of the computer.

Function ComFileCopy String existingFilepath String newFilepath Boolean failIfExists Returns Boolean

Copys existingFilepath to newFilepath. If failIfExists is True and newFilepath already exists, then an error is returned.

Returns True for success, False for failure.

Function ComFileDelete String filePath Returns Boolean

Deletes the file specified by filePath.

Returns True for success, False for failure.

Function ComFileExists String filePath Returns Boolean

Returns True if filePath exists, otherwise returns False.

Function ComFileExists3 String path Returns Integer

Introduced in version 9.5.0.45

Returns 1 if the file exists, 0 if the file does not exist, and -1 if unable to check because of directory permissions or some other error that prevents the ability to obtain the information.

Function ComFileOpen String filePath Variant accessMode Variant shareMode Variant createDisposition Variant attributes Returns Boolean

This method should only be called on Windows operating systems. It's arguments are similar to the Windows Platform SDK function named CreateFile. For Linux, MAC OS X, and other operating system, use the OpenForRead, OpenForWrite, OpenForReadWrite, and OpenForAppend methods.

Opens a file for reading or writing. The arguments mirror the Windows CreateFile function:

Access Modes:
GENERIC_READ	(0x80000000)
GENERIC_WRITE (0x40000000)

Share Modes:
FILE_SHARE_READ(0x00000001)
FILE_SHARE_WRITE(0x00000002)

Create Dispositions
CREATE_NEW          1
CREATE_ALWAYS       2
OPEN_EXISTING       3
OPEN_ALWAYS         4
TRUNCATE_EXISTING   5

// Attributes:
FILE_ATTRIBUTE_READONLY         0x00000001
FILE_ATTRIBUTE_HIDDEN           0x00000002
FILE_ATTRIBUTE_SYSTEM           0x00000004
FILE_ATTRIBUTE_DIRECTORY        0x00000010
FILE_ATTRIBUTE_ARCHIVE          0x00000020
FILE_ATTRIBUTE_NORMAL           0x00000080
FILE_ATTRIBUTE_TEMPORARY	   0x00000100

Returns True for success, False for failure.

Function ComFileRead Integer maxNumBytes Returns Variant

Reads bytes from the currently open file. maxNumBytes specifies the maximum number of bytes to read. Returns an empty byte array on error.

Returns null on failure

Function ComFileReadBd Integer maxNumBytes cComChilkatBinData binData Returns Boolean

Introduced in version 9.5.0.64

Reads bytes from the currently open file. maxNumBytes specifies the maximum number of bytes to read. Appends the bytes to the binData.

Returns True for success, False for failure.

Determine File Type from Binary Content of File

Function ComFileRename String existingFilepath String newFilepath Returns Boolean

Renames a file from existingFilepath to newFilepath.

Returns True for success, False for failure.

Function ComFileSeek Integer offset Integer origin Returns Boolean

Sets the file pointer for the currently open file. The offset is an offset in bytes from the origin. The origin can be one of the following:

0 = Offset is from beginning of file.
1 = Offset is from current position of file pointer.
2 = Offset is from the end-of-file (offset may be negative).

Returns True for success, False for failure.

Function ComFileSize String filePath Returns Integer

Returns the size, in bytes, of a file. Returns -1 for failure.

Returns True for success, False for failure.

Function ComFileWrite Variant data Returns Boolean

Writes bytes to the currently open file.

Returns True for success, False for failure.

Function ComFileWriteBd cComChilkatBinData binData Integer offset Integer numBytes Returns Boolean

Introduced in version 9.5.0.64

Writes the contents of binData to the currently open file. To specify the entire contents of binData, set both offset and numBytes equal to 0. To write all remaining data starting at offset, then set numBytes equal to 0.

Returns True for success, False for failure.

Unzip Binary File to Stream

Function ComGenBlockId Integer index Integer length String encoding Returns String

Introduced in version 9.5.0.58

This is purely a utility/convenience method -- initially created to help with block file uploads to Azure Blob storage. It generates a block ID string that is the decimal representation of the index in length chars, and then encoded according to encoding (which can be an encoding such as "base64", "hex", "ascii", etc.) For example, if index = 8, length = 12, and encoding = "base64", then the string "00000012" is returned base64 encoded.

Returns null on failure

Function ComGetDirectoryName String path Returns String

Introduced in version 9.5.0.64

Returns the directory information for the specified path string.

GetDirectoryName('C:\MyDir\MySubDir\myfile.ext') returns 'C:\MyDir\MySubDir\'
GetDirectoryName('C:\MyDir\MySubDir') returns 'C:\MyDir\'
GetDirectoryName('C:\MyDir\') returns 'C:\MyDir\'
GetDirectoryName('C:\MyDir') returns 'C:\'
GetDirectoryName('C:\') returns 'C:\'

Returns null on failure

Demonstrate Directory Path Functions

Function ComGetExtension String path Returns String

Introduced in version 9.5.0.64

Returns the extension of the specified path string.

GetExtension('C:\mydir.old\myfile.ext') returns '.ext'
GetExtension('C:\mydir.old\') returns ''

Returns null on failure

Demonstrate Directory Path Functions

Function ComGetFileName String path Returns String

Introduced in version 9.5.0.64

Returns the file name and extension of the specified path string.

GetFileName('C:\mydir\myfile.ext') returns 'myfile.ext'
GetFileName('C:\mydir\') returns ''

Returns null on failure

Demonstrate Directory Path Functions

Function ComGetFileNameWithoutExtension String path Returns String

Introduced in version 9.5.0.64

Returns the file name of the specified path string without the extension.

GetFileNameWithoutExtension('C:\mydir\myfile.ext') returns 'myfile'
GetFileNameWithoutExtension('C:\mydir\') returns ''

Returns null on failure

Demonstrate Directory Path Functions

Function ComGetFileTime String path Integer which Returns cComCkDateTime

Introduced in version 9.5.0.71

Gets one of the following date/times for a file:

0: Last-modified
1: Last-access
2: Creation
The "path" argument indicates which time to return. The values can be 0, 1, or 2.

Note: Linux filesystems do not keep a file's creation date/time. In such a case, this method will return the last-modified time.

Returns null on failure

Function ComGetLastModified String path Returns cComCkDateTime

Introduced in version 9.5.0.66

Gets the last-modified date/time for a file.

Returns null on failure

Function ComGetNumBlocks Integer blockSize Returns Integer

Introduced in version 9.5.0.58

Returns the number of blocks in the currently open file. The number of bytes per block is specified by blockSize. The number of blocks is the file size divided by the blockSize, plus 1 if the file size is not evenly divisible by blockSize. For example, if the currently open file is 60500 bytes, and if the blockSize is 1000 bytes, then this method returns a count of 61 blocks.

Returns -1 if no file is open. Return 0 if the file is completely empty (0 bytes).

File Read Blocks

Function ComGetTempFilename String dirPath String prefix Returns String

Creates a temporary filepath of the form dirPath\prefix_xxxx.TMP Where "xxxx" are random alpha-numeric chars. The returned filepath is guaranteed to not already exist.

Returns null on failure

Function ComOpenForAppend String filePath Returns Boolean

Opens a file for appending. If filePath did not already exists, it is created. When an existing file is opened with this method, the contents will not be overwritten and the file pointer is positioned at the end of the file.

If the open/create failed, then error information will be available in the FileOpenError and FileOpenErrorMsg properties.

Returns True for success, False for failure.

Function ComOpenForRead String filePath Returns Boolean

Opens a file for reading. The file may contain any type of data (binary or text) and it must already exist. If the open failed, then error information will be available in the FileOpenError and FileOpenErrorMsg properties.

Returns True for success, False for failure.

Function ComOpenForReadWrite String filePath Returns Boolean

Opens a file for reading/writing. If filePath did not already exists, it is created. When an existing file is opened with this method, the contents will not be overwritten, but the file pointer is positioned at the beginning of the file.

If the open/create failed, then error information will be available in the FileOpenError and FileOpenErrorMsg properties.

Returns True for success, False for failure.

Function ComOpenForWrite String filePath Returns Boolean

Opens a file for writing. If filePath did not already exists, it is created. When an existing file is opened with this method, the contents will be overwritten. (For example, calling OpenForWrite on an existing file and then immediately closing the file will result in an empty file.) If the open/create failed, then error information will be available in the FileOpenError and FileOpenErrorMsg properties.

Returns True for success, False for failure.

Function ComReadBinaryToEncoded String filePath String encoding Returns String

Reads the entire contents of a binary file and returns it as an encoded string (using an encoding such as Base64, Hex, etc.) The encoding may be one of the following strings: base64, hex, qp, or url.

Returns null on failure

Base64 Encode a File

Function ComReadBlock Integer blockIndex Integer blockSize Returns Variant

Introduced in version 9.5.0.58

Reads the Nth block of a file, where the size of each block is specified by blockSize. The first block is at blockIndex 0. If the block to be read is the last in the file and there is not enough data to fill an entire block, then the partial block is returned.

Returns null on failure

File Read Blocks

Function ComReadEntireFile String filePath Returns Variant

Reads the entire contents of a binary file and returns the data.

Returns null on failure

Function ComReadEntireTextFile String filePath String charset Returns String

Reads the entire contents of a text file, interprets the bytes according to the character encoding specified by charset, and returns the text file as a string.

Returns null on failure

Function ComReassembleFile String partsDirPath String partPrefix String partExtension String reassembledFilename Returns Boolean

Reassembles a file previously split by the SplitFile method.

Returns True for success, False for failure.

Example: Reassemble a Previously Split File

Function ComReplaceStrings String filePath String charset String existingString String replacementString Returns Integer

Replaces all occurrences of existingString with replacementString in a file. The character encoding, such as utf-8, ansi, etc. is specified by charset.

Function ComSetCurrentDir String dirPath Returns Boolean

Sets the current working directory for the calling process to dirPath.

Returns True for success, False for failure.

Function ComSetFileTimes String filePath cComCkDateTime createTime cComCkDateTime lastAccessTime cComCkDateTime lastModTime Returns Boolean

Sets the create date/time, the last-access date/time, and the last-modified date/time for a file. For non-Windows filesystems where create times are not implemented, the createTime is ignored.

Function ComSetLastModified String filePath cComCkDateTime lastModified Returns Boolean

Sets the last-modified date/time for a file.

Function ComSplitFile String fileToSplit String partPrefix String partExtension Integer partSize String destDir Returns Boolean

Splits a file into chunks. Please refer to the example below:

Returns True for success, False for failure.

Example: Split File into Chunks

Function ComTreeDelete String path Returns Boolean

Deletes an entire directory tree (all files and sub-directories).

Returns True for success, False for failure.

Function ComWriteEntireFile String filePath Variant fileData Returns Boolean

Opens/creates filePath, writes fileData, and closes the file.

Returns True for success, False for failure.

Function ComWriteEntireTextFile String filePath String textData String charset Boolean includedPreamble Returns Boolean

Opens filePath, writes textData using the character encoding specified by charset, and closes the file. If includedPreamble is True and the charset is Unicode or utf-8, then the BOM is included at the beginning of the file.

Returns True for success, False for failure.

Base64 Encode a File