Package 'Rparadox'

Description

This function explicitly closes a Paradox database file associated with a pxdoc_t external pointer and releases its resources.

Usage

pxlib_close_file(pxdoc)

Arguments

Value

Invisible NULL.

Description

Retrieves all records from an open Paradox database file and returns them as a tibble, ready for use in R.

Usage

pxlib_get_data(pxdoc)

Arguments

Details

This function provides a high-level interface for reading Paradox data. The heavy lifting is done by a C-level function (R_pxlib_get_data) which efficiently reads the raw data into memory. This R function then acts as a wrapper to perform crucial post-processing steps:

• It identifies columns containing binary (BLOB) data and correctly converts them into blob objects.

• It ensures that date/time columns are properly classed for seamless integration with other R functions.

The result is a clean, modern tibble that is fully compatible with the tidyverse ecosystem.

Value

A tibble containing the data from the Paradox file. Each row represents a record and each column represents a field. If the file contains no records, an empty tibble is returned.

Examples

# Define the path to the demo database included with the package
db_path <- system.file("extdata", "biolife.db", package = "Rparadox")

# Open the file handle
pxdoc <- pxlib_open_file(db_path)

if (!is.null(pxdoc)) {
  # Read all data into a tibble
  biolife_data <- pxlib_get_data(pxdoc)

  # Always close the file handle when finished
  pxlib_close_file(pxdoc)

  # Work with the data
  print(biolife_data)
}

Description

Retrieves metadata from an open Paradox file handle without reading the entire dataset.

Usage

pxlib_metadata(pxdoc)

Arguments

Value

A list containing:

Examples

db_path <- system.file("extdata", "country.db", package = "Rparadox")
pxdoc <- pxlib_open_file(db_path)
if (!is.null(pxdoc)) {
  metadata <- pxlib_metadata(pxdoc)
  print(metadata)
  pxlib_close_file(pxdoc)
}

Description

Opens a Paradox database (.db) file and prepares it for reading. This function serves as the entry point for interacting with a Paradox database.

Usage

pxlib_open_file(path, encoding = NULL, password = NULL)

Arguments

Details

This function initializes a connection to a Paradox file via the underlying C library. It automatically performs two key setup tasks:

1. Encoding Override: It allows the user to specify the character encoding of the source file via the encoding parameter. This is crucial for legacy files where the encoding stored in the header may be incorrect. If encoding is NULL, the function will attempt to use the codepage from the file header.

2. BLOB File Attachment: It automatically searches for an associated BLOB file (with a .mb extension, case-insensitively) in the same directory and, if found, attaches it to the database handle.

Encryption Handling

This function automatically handles encrypted Paradox files:

1. If the file is not encrypted, the password parameter is ignored

2. If the file is encrypted and password is provided, it validates the password

3. If the file is encrypted and password is NULL, an error is thrown

4. If the provided password is incorrect, an error is thrown

When a file is successfully opened with the correct password, all subsequent operations (like pxlib_get_data()) will automatically decrypt the data.

Resource Management

It's important to always close the file handle using pxlib_close_file() when you're done to prevent resource leaks. Using on.exit() is recommended:

px_doc <- pxlib_open_file("myfile.db", password = "secret")
on.exit(pxlib_close_file(px_doc), add = TRUE)
# ... work with the file ...

Value

An external pointer of class "pxdoc_t" representing the opened Paradox file, or NULL if the file could not be opened (with a warning).

Examples

# Example 1: Open a bundled demo file (biolife.db)
db_path <- system.file("extdata", "biolife.db", package = "Rparadox")
pxdoc <- pxlib_open_file(db_path)
if (!is.null(pxdoc)) {
  # normally you'd read data here
  pxlib_close_file(pxdoc)
}

# Example 2: Open a file with overridden encoding (of_cp866.db)
db_path2 <- system.file("extdata", "of_cp866.db", package = "Rparadox")
pxdoc2 <- pxlib_open_file(db_path2, encoding = "cp866")
if (!is.null(pxdoc2)) {
  # read some data ...
  pxlib_close_file(pxdoc2)
}

# Example 3: Open an encrypted file with password
db_path3 <- system.file("extdata", "country_encrypted.db", package = "Rparadox")
px_doc <- pxlib_open_file(db_path3, password = "rparadox")
data <- pxlib_get_data(px_doc)
pxlib_close_file(px_doc)

Description

A high-level, user-friendly wrapper function that reads an entire Paradox database file (.db) and returns its contents as a tibble.

Usage

read_paradox(path, encoding = NULL, password = NULL)

Arguments

Details

This function simplifies the process of reading Paradox files by handling the complete workflow in a single call:

1. It validates the input path and encoding.

2. It safely opens a handle to the file using pxlib_open_file().

3. It ensures the file handle is always closed using on.exit(), even if errors occur during data reading.

4. It reads the data using pxlib_get_data().

5. It returns a clean tibble.

If the specified file does not exist, the function will issue a warning and return an empty tibble.

Value

A tibble containing the data from the Paradox file.

Examples

# Read the demo database in one step
db_path <- system.file("extdata", "biolife.db", package = "Rparadox")
if (file.exists(db_path)) {
  biolife_data <- read_paradox(db_path)
  print(biolife_data)
}