HDescribeFile (Function)

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How to describe a data file by programming?

List of HFSQL properties used to describe a data file by programming

Types of data files that can be described with the HDescribeFile function

Syntax 2: Description of data file (compatibility with 5.5)

See also

HDescribeFile (Function)

In french: HDécritFichier

Not available with this kind of connection

Describes a data file by programming.

After the call to HDescribeFile:

the data file can be used like any other file described in the analysis.
the description of the data file cannot be modified anymore.
the description variable of the data file is re-initialized. A new description of data file can be performed.

To cancel the description of a data file by programming, use HCancelDeclaration.

Versions 17 and later

This function is now available for iPhone/iPad applications.

New in version 17

This function is now available for iPhone/iPad applications.

Versions 18 and later

This function is now available in Windows Store apps mode.

New in version 18

This function is now available in Windows Store apps mode.

Versions 21 and later

This function is now available in Universal Windows 10 App mode.

New in version 21

This function is now available in Universal Windows 10 App mode.

Remark: From version 19, HFSQL is the new name of HyperFileSQL.

Example

// Example using syntax 1
AFile is File Description
AnItem is Item Description
Customer is Data Source = "Customer"

// Describe the "Customer" data file
AFile..Name = "Customer"
AFile..Type = hFileNormal
AFile..FicCryptMethod = hCryptStandard

// Describe the "LastName" item
AnItem..Name = "LASTNAME"
AnItem..Type = hItemText
AnItem..Size = 40
AnItem..KeyType = hUniqueKey
HDescribeItem(AFile, AnItem)

// Describe the "FirstName" item
AnItem..Name = "FIRSTNAME"
AnItem..Type = hItemText
AnItem..Size = 40
HDescribeItem(AFile, AnItem)

// Validate the data file description
HDescribeFile(AFile)
...

// Create the data file named Customer (recognized because declared as data source)
HCreation(Customer)

// Create a record
Customer.LastName = "Smith"
Customer.FirstName = "Andrew"
HAdd(Customer)

// Example using syntax 2
AFileDescription is File Description
AnItem is Item Description
dsSource is Data Source

// Describe the "CUSTOMER" data file
AFileDescription..Name = "CUSTOMER"
AFileDescription..Type = hFileNormal
AFileDescription..FicCryptMethod = hCryptStandard

// Describe the "LASTNAME" item
AnItem..Name = "LASTNAME"
AnItem..Type = hItemText
AnItem..Size = 40
AnItem..KeyType = hUniqueKey
HDescribeItem(AFileDescription, AnItem)

// Describe the "FIRSTNAME" item
AnItem..Name = "FIRSTNAME"
AnItem..Type = hItemText
AnItem..Size = 40
HDescribeItem(AFileDescription, AnItem)

// Validate the data file description
HDescribeFile(dsSource, AFileDescription)

HCreation(dsSource)

Syntax

Describing a data file by programming Hide the details

<Result> = HDescribeFile(<Data file>)

<Result>: Boolean

True if the description of the data file is valid and if it can be used,
False if a problem occurred. HErrorInfo is used to identify the error.

<Data file>: File Description variable

Name of the File description type variable (see Notes paragraph) used to describe the data file. The name of the data file will be defined by ..Name.

Describing a data file by programming using a data source Hide the details

<Result> = HDescribeFile(<Data source> , <Data file>)

<Result>: Boolean

True if the description of the data file is valid and if it can be used,
False if a problem occurred. HErrorInfo is used to identify the error.

<Data source>: Data Source variable

Name of the Data source variable associated with the data file.

<Data file>: File Description variable

Name of the File description type variable (see Notes paragraph) used to describe the data file. The name of the data file will be defined by ..Name.

Describing a data file in Hyper File 5.5 format by programming (backward compatibility only) Hide the details

<Result> = HDescribeFile(<Data file> , <Abbreviation> [, <Access path>])

<Result>: Boolean

True if the operation was performed,
False if a problem occurred. HErrorInfo is used to identify the error.

<Data file>: Character string (with or without quotes)

Name of the temporary data file to create. This temporary data file is in Hyper File 5.5 format.

<Abbreviation>: 2-character string

Data file prefix.

<Access path>: Optional character string

Name of the directory or drive in which the physical data file will be created. If this parameter is not specified, the data file will be created (HCreation) in the current program directory.

Remarks

How to describe a data file by programming?

To describe a data file by programming, you must:

Solution 1 (syntax 1): Direct description
1. Use the File description, Item description, Link description and FullTextIndex description variables (if necessary).
2. Describe the characteristics of the data file, items, links and full-text indexes (if necessary) via the HFSQL properties.
3. Define the description of items with HDescribeItem.
4. Define the description of full-text indexes with HDescribeFullTextIndex.
5. Define the description of the data file (HDescribeFile) and links if necessary (HDescribeLink).
Versions 24 and later
Solution 2 (syntax 2): Description using a data source
This solution allows associating the data file described to a data source. In this case, when this variable is deleted, the data file will also be deleted.
Caution: To use this syntax, you must use an "automatic" data source. See Project description: Compilation tab for more details.
1. Declare a Data source variable.
2. Use the File description, Item description, Link description and FullTextIndex description variables (if necessary).
3. Describe the characteristics of the data file, items, links and full-text indexes (if necessary) via the HFSQL properties.
4. Define the description of items with HDescribeItem.
5. Define the description of full-text indexes with HDescribeFullTextIndex.
6. Associate the data file description with the data source (HDescribeFile, syntax 2) and links if necessary (HDescribeLink).
New in version 24
Solution 2 (syntax 2): Description using a data source
This solution allows associating the data file described to a data source. In this case, when this variable is deleted, the data file will also be deleted.
Caution: To use this syntax, you must use an "automatic" data source. See Project description: Compilation tab for more details.
1. Declare a Data source variable.
2. Use the File description, Item description, Link description and FullTextIndex description variables (if necessary).
3. Describe the characteristics of the data file, items, links and full-text indexes (if necessary) via the HFSQL properties.
4. Define the description of items with HDescribeItem.
5. Define the description of full-text indexes with HDescribeFullTextIndex.
6. Associate the data file description with the data source (HDescribeFile, syntax 2) and links if necessary (HDescribeLink).
Solution 2 (syntax 2): Description using a data source
This solution allows associating the data file described to a data source. In this case, when this variable is deleted, the data file will also be deleted.
Caution: To use this syntax, you must use an "automatic" data source. See Project description: Compilation tab for more details.
1. Declare a Data source variable.
2. Use the File description, Item description, Link description and FullTextIndex description variables (if necessary).
3. Describe the characteristics of the data file, items, links and full-text indexes (if necessary) via the HFSQL properties.
4. Define the description of items with HDescribeItem.
5. Define the description of full-text indexes with HDescribeFullTextIndex.
6. Associate the data file description with the data source (HDescribeFile, syntax 2) and links if necessary (HDescribeLink).

List of HFSQL properties used to describe a data file by programming

The following properties are available in read/write.


CtAccess	..CtAccess is used to manage the type of access to the data file during the OLE DB connection to a specific table.
CtDatabase	..CtDatabase is used to manage the OLE DB data source during the OLE DB connection to a specific table.
CtDescribedAccess	..CtDescribedAccess is used to manage the type of access to the data file during the OLE DB connection to a specific table.
CtDescribedCaption	..CtDescribedCaption is used to manage the caption of the connection to the OLE DB data source.
CtDescribedDatabase	..CtDescribedDatabase is used to manage the OLE DB data source during the OLE DB connection to a specific table.
CtDescribedOLEDBProvider	..CtDescribedOLEDBProvider is used to manage the name of the OLE DB provider (also called OLE DB server).
CtDescribedPassword	..CtDescribedPassword is used to define the password that will be used to open the file during an OLE DB connection (file defined by programming only).
CtDescribedUserName	..CtDescribedUserName is used to configure the name of the user that will be used during the OLE DB connection to a specific table.
CtOLEDBProvider	..CtOLEDBProvider is used to manage the name of the OLE DB provider (also called OLE DB server).
CtUserName	..CtUserName is used to configure the user name that will be used during the OLE DB connection to a specific table.
DescribedDirectory	..DescribedDirectory is used to manage the physical directory of HFSQL files.
DescribedName	..DescribedName is used to manage the logical name of HFSQL files.
DescribedPhysicalName	..DescribedPhysicalName is used to manage the physical name of HFSQL files.
Directory	..Directory is used to manage the physical directory of HFSQL files.
FicCryptMethod	..FicCryptMethod is used to configure the encryption mode of the data file.
Format	..Format is used to configure the format of data in a data file.
HugeFile	..HugeFile is used to configure the maximum size of a data file.
LogDirectory	..LogDirectory is used to manage the directory of the log file described in the analysis.
LogMethod	..LogMethod is used to: find out the log mode used for a data file (file defined in the data model editor or by programming). define the log mode used for a data file (when the file is described by programming).
MmoCryptMethod	..MmoCryptMethod is used to configure the encryption mode of memo file (.MMO extension) associated with the data file.
MmoPackMethod	..MmoPackMethod is used to configure the compression mode of the MMO file (containing the binary and text memos) associated with a data file.
Name	..Name is used to find out: the name of the font associated with a Font variable. the name of a control, report or report block. the name of a control, group of controls or window. the name of a control, group of controls or page.
Name55	..Name55 is used to manage the logical name of a data file in Hyper File 5.5 format not migrated and found in an analysis in WINDEV 19. format.
NdxCryptMethod	..NdxCryptMethod is used to configure the encryption mode of index file (.NDX extension) associated with the data file.
PhysicalName	..PhysicalName is used to manage the physical name of HFSQL files.
Secure	..Secure is used to configure the security level for file encryption.
TextItemCompleted	..TextItemCompleted is used to configure the management of text items in a HFSQL file.
Type	..Type is used to find out: the type of element described by programming (file or item description) or not (file or item defined in the data model editor, view or query). the type of object. the type of value stored in a variant.
WDD55	..WDD55 is used to: Find out the name and full path of the WDD file in Hyper File 5.5 format. Define the name and full path of the WDD file in Hyper File 5.5 format.
WDD55Password	..WDD55Password is used to specify the password of the analysis in 5.5 format during the description by programming of a file in Hyper File 5.5 format in an analysis in Hyper File Classic format.

Types of data files that can be described with the HDescribeFile function

..Type is used to specify the type of data file to create.

The following types can be created by HDescribeFile:


hFileAS400	AS400 file
hFileNormal	Standard file
hFileOLEDB	OLE DB file
hFileOracle	Oracle file
Versions 16 and later hFileSQLAzure New in version 16 hFileSQLAzure hFileSQLAzure	SQL Azure file
hFileSQLServer	SQL Server file
hFileSybase	Sybase file
hFileXBase	xBase file

Syntax 2: Description of data file (compatibility with 5.5)

This syntax is used to create some temporary data files in Hyper File 5.5 format. This syntax can only be used in an application developed with WINDEV 5.5 or WEBDEV 1.5 and migrated to WINDEV 7 (or later). To use this function:

the analysis in Hyper File 5.5 format must be accessible on the development computer and it must be loaded.
the path of the WINDEV 5.5 analysis must be specified in the characteristics of the analysis ("Details" tab).

Business / UI classification : Business Logic

Component : wd250hf.dll