HDescribeFile (Function)

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How to describe a data file through programming?
List of HFSQL properties used to describe a data file through programming
Types of data files that can be described with the HDescribeFile function
Syntax 2: Description of the data file (compatibility with 5.5)

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HDescribeFile (Function)

In french: HDécritFichier

Not available with this kind of connection

Describes a data file programmatically.

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 reinitialized. A new description of data file can be performed.

To programmatically cancel the data file description, use HCancelDeclaration.

Example

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

// Describe the "Customer" data file
AFile.Name = "Customer"
AFile.Type = hFileNormal
AFile.FicEncryption = hEncryptionStandard

// 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)
HCréation(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.FicEncryption = hEncryptionStandard

// Description of 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)

HCréation(dsSource)

Syntax

Describing a data file through 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 occurs. HErrorInfo is used to identify the error.

<Data file>: File Description variable

Name of the File Description variable (see the Notes paragraph) used to describe the data file. The name of the data file will be defined with the Name property.

Describing a data file through 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 occurs. 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 variable (see the Notes paragraph) used to describe the data file. The name of the data file will be defined with the Name property.

Describing a data file in Hyper File 5.5 format through 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 occurs. HErrorInfo is used to identify the error.

<Data file>: Character string

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 through programming?

To describe a data file through 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, its items, links and full-text indexes (if necessary) using 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).
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. For more details, see Project description: Compilation tab.
1. Declare a variable of type Data source.
2. Use the File Description, Item Description, Link description and FullTextIndex Description variables (if necessary).
3. Describe the characteristics of the data file, its items, links and full-text indexes (if necessary) using 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 through programming

The following properties are available in read/write mode.


CtAccess	The CtAccess property is used to set the type of access to the data file when connecting to a specific table via OLE DB.
CtDatabase	The CtDatabase property is used to set the OLE DB data source when connecting to a specific table via OLE DB.
CtDescribedAccess	The CtDescribedAccess property is used to set the type of access to the data file when connecting to a specific table via OLE DB.
CtDescribedCaption	The CtDescribedCaption property is used to get and set the caption of the connection to the OLE DB data source.
CtDescribedDatabase	The CtDescribedDatabase property is used to set the OLE DB data source when connecting to a specific table via OLE DB.
CtDescribedOLEDBProvider	The CtDescribedOLEDBProvider property is used to get and set the name of the OLE DB provider (also called OLE DB server).
CtDescribedPassword	The CtDescribedPassword property allows you to set the password used to open the data file in an OLE DB connection (file defined in the code only).
CtDescribedUserName	The CtDescribedUserName property is used to set the username that will be used when connecting to a specific table via OLE DB.
CtOLEDBProvider	The CtOLEDBProvider property is used to get and set the name of the OLE DB provider (also called OLE DB server).
CtUserName	The CtUserName property is used to set the username that will be used when connecting to a specific table via OLE DB.
DescribedDirectory	The DescribedDirectory property is used to manage the physical directory of HFSQL files.
DescribedName	The DescribedName property is used to handle the logical name of HFSQL data files (ignoring possible changes made by HAlias).
DescribedPhysicalName	The DescribedPhysicalName property is used to manage the physical name of HFSQL data files.
Directory	The Directory property is used to manage the physical directory of HFSQL files.
FicEncryption	The FicEncryption property is used to set the encryption method of a data file.
Format	The Format property is used to define the data format of a data file.
HugeFile	The HugeFile property is used to configure the maximum size of a data file.
LogDirectory	The LogDirectory property is used to manage the directory of the log file described in the analysis.
LogMethod	The LogMethod property is used to: find out the log mode used for a data file (file defined in the data model editor or through programming). define the log mode used for a data file (when the file is described through programming).
MmoEncryption	The MmoEncryption property is used to set the encryption method of the memo file (.MMO) associated with the data file.
MmoPackMethod	The MmoPackMethod property is used to set the compression mode of the MMO file (containing text and binary memos) associated with the data file.
Name	The Name property is used to get: 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	The Name55 property is used to manipulate the logical name of a Hyper File 5.5 data file that has not been migrated and is located in a WINDEV 19 analysis.
NdxEncryption	The NdxEncryption property is used to configure the encryption method for the index (.NDX) file associated with the data file.
PhysicalName	The PhysicalName property is used to manage the physical name of HFSQL data files.
Secure	The Secure property is used to configure the security level of data file encryption.
TextItemCompleted	The TextItemCompleted property is used to manage text items in an HFSQL data file.
Type	The Type property is used to get: the type of element (data file or item) defined programmatically or in the data model editor, view or query. the type of object. the type of data held in a Variant.
WDD55	The WDD55 property is used to: Get the name and full path of the Hyper File 5.5 WDD file. Set the name and full path of the Hyper File 5.5 WDD file.
WDD55Password	The WDD55Password property is used to specify the password of the 5.5 analysis that contains a Hyper File 5.5 data file used in an HFSQL Classic analysis.

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

The Type property specifies the type of data file to be created.

The following types can be created with HDescribeFile:


hFileAS400	AS400 file
hFileNormal	Standard file
hFileOLEDB	OLE DB file
hFileOracle	Oracle file
hFileSQLAzure	SQL Azure file
hFileSQLServer	SQL Server file
hFileSybase	Sybase file
hFileXBase	xBase file

Syntax 2: Description of the 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: wd290hf.dll