The
Unalterable property is used to configure the unalterability of a data file: the data file cannot be modified; only additions can be made.
You can:
- Find out whether a data file is unalterable or not (data file defined in the data model editor or through programming).
- Define the characteristics regarding the unalterability of a data file (when describing the data file through programming only).
Reminder: Making files unalterable:
- avoids programming errors by preventing modification or deletion (via HModify/HDelete, or via a query).
- adds a hash of the record content to each record. This hash is an HMAC-SHA256 hash, whose key is derived from the file encryption password.
AFile is File Description
AnItem is Item Description
// Describe the "Customer" data file
AFile.Name = "Customer"
AFile.Type = hFileNormal
AFile.Unalterable = True
// Item description
AnItem.Name = "Message"
AnItem.Type = hItemText
AnItem.Size = 40
HDescribeItem(AFile, AnItem)
// Validate the data file description
HDescribeFile(AFile)
Syntax
Finding out whether a data file is unalterable or not Hide the details
<Result> = <Data file>.Unalterable
<Result>: Boolean
- True if the data file is unalterable,
- False otherwise.
<Data file>: Character string
Name of the data file used. This name was defined in the data model editor or with the File Description type.
Defining the characteristics regarding the unalterability of a data file (data file defined through programming) Hide the details
<Data file>.Unalterable = <Unalterability>
<Data file>: Character string
Name of the data file used. This name was defined by the File Description type.
<Unalterability>: Boolean
- True if the data file must be unalterable,
- False otherwise.