File Description (Variable type)

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Properties specific to the description of data files
How to describe data files programmatically?
Handling the items of a data file described programmatically
LogMethod

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File Description (Variable type)

In french: Description de Fichier (Type de variable)

Available only with these kinds of connection

The File Description variable is used to programmatically describe data files. The description of each data file is validated by HDescribeFile.

After this validation:

This data file can be handled like any other data file described in the analysis.
The "File Description" variable is reinitialized and can be used to describe another data file.

Example

AFile is File Description
MyFile1, MyFile2 are File Descriptions

// Describe the "CUSTOMER" data file
AFile is File Description

AFile.Name = "CUSTOMER"
AFile.Type = hFileNormal
AFile.FicEncryption = hEncryptionStandard

// Description of the data file items
...

// Validate the description of "CUSTOMER"
HDescribeFile(AFile)

Syntax

Declaring one or more descriptions of data files Hide the details

<Variable name> is File Description
<Variable name 1>, <Variable name 2> are File Descriptions

<Variable name>:

Name of the "File Description" variable to declare.
Note: The keywords une and des are not mandatory: they are approval words..

Describing a "File Description" variable Hide the details

To describe a "File Description" variable:

Use the WLanguage properties specific to the descriptions of data files. For more details, see the remarks.

To validate the description of a "File Description" type variable:

Use the HDescribeFile function.

Remarks

Properties specific to the description of data files

The table below presents the properties specific to the description of data files:

Note: Properties in bold followed by an asterisk ( * ) must be initialized when describing a data file programmatically.

Property name	Effect

CtAccess	Type of data file access when connecting OLE DB to a specific table (taking into account modifications made by HConnect).
CtDatabase	OLE DB data source when connecting to a specific table (taking into account the changes made with HConnect).
CtDescribedAccess	Type of access to the data file when connecting OLE DB to a specific table (without taking into account modifications made by the HConnect function).
CtDescribedCaption	Caption of the connection to the OLE DB data source.
CtDescribedDatabase	OLE DB data source when connecting to a specific table (ignoring the changes made with HConnect).
CtDescribedOLEDBProvider	Name of the OLE DB server (ignoring the changes made with HConnect).
CtDescribedPassword	Password used to open the data file during an OLE DB connection.
CtDescribedUserName	Name of the user during an OLE DB connection (ignoring the changes made with HConnect).
CtOLEDBProvider	Name of the OLE DB server used (taking into account the changes made with HConnect).
CtUserName	Name of the user during an OLE DB connection (taking into account the changes made by HConnect).
DescribedDirectory	Physical directory of HFSQL data files (this property does not take into account directory changes made using HChangeDir or HSubstDir).
DescribedName	Logical name of a data file.
DescribedPhysicalName	Physical name of HFSQL data files (without taking into account name changes made using HChangeName).
Directory	Physical directory of HFSQL data files (this property takes into account directory changes made using HChangeDir or HSubstDir).
FicEncryption	Data file encryption mode.
Format	Format of data in the data file (ANSI or Unicode).
HugeFile	Maximum size of a data file.
LogDirectory	Directory of log file described in the analysis.
LogMethod	Log mode of a data file.
MmoEncryption	Encryption mode of memo file (.MMO extension) associated with the data file.
MmoPackMethod	Compression mode of the MMO file (containing text and binary memos) associated with the data file.
Name ( * )	Name of the HFSQL data file.
Name55	Logical name of the data file in Hyper File 5.5 format present in a WINDEV analysis.
NdxEncryption	Encryption mode of index file associated with the data file.
NullableIndex	Support of NULL values in key items.
NullSupported	Support of NULL values.
PhysicalName	Physical name of data files.
RepeatableReadSupported	The file is used in an HFSQL Client/Server transaction that includes a "Repeatable Read" isolation level.
Secure	Security level regarding the encryption of data files.
TextItemCompleted	Fills (or not) the text items with space characters.
Type	Type of data file.
Unalterable	Unalterability of data files.
WDD55	Path of the WDD file in 5.5 format used to handle the data files in 5.5 format in a WINDEV application.
WDD55Password	Password used to manipulate a data file programmatically defined in Hyper File 5.5 format in a WINDEV analysis.

How to describe data files programmatically?

To describe data files programmatically:

Declare the "File Description", "Item Description", "FullTextIndex Description" and "Link description" variables (if necessary).
For each data file:
- Describe the characteristics of the data file using HFSQL properties.
- Describe the characteristics of the items using HFSQL properties.
- Validate the description of each item (HDescribeItem).
- If necessary, describe the characteristics of full-text indexes using HFSQL properties.
- Validate the description of each full-text index (HDescribeFullTextIndex).
- Validate the data file description (HDescribeFile).
If necessary, describe the characteristics of the links using HFSQL properties.
If necessary, validate the description of each link (HDescribeLink).

Handling the items of a data file described programmatically

When creating a data file in the data model editor, the names of the data files and items are automatically recognized by the compiler.

When creating a data file using a "File Description" variable, the names of the data file and its items can be defined with the Name property. These names are not automatically recognized by the compiler. A compilation error occurs if these names are used to identify the data file or the items.

The name of the data file must be declared as data source using the data source keyword, for the compiler to recognize this name. This data file can be handled by its name in the code editor.

For example:

AFile is File Description
...
AFile.Name = "CUSTOMER"
...
HDescribeFile("CUSTOMER")
...
CUSTOMER is Data Source
...
HReadFirst(CUSTOMER, "CUSTNAME")

Remark: It is also possible to declare the name of the data file with the keyword Extern.. However, the process execution will be slower.

LogMethod

When the data file is described programmatically:

if the data file is logged and if no item is logged, all the items (except for the composite keys) are automatically logged.
if the data file is logged and if at least one item is logged, the other items are not modified.