sqrlConfig: Configuration Files

In SQRL: Enhances Interaction with 'ODBC' Databases

Configuration Files

Description

This material does not describe a function, but (rather) the file format used to configure SQRL interfaces and RODBC communications.

Configuration files can be used to define new data sources, set blanket parameter values for existing sources, or set individually named parameter values.

Example Configuration File

# Parameters for RODBC::odbcConnect/RODBC::odbcDriverConnect.
dsn                 = NULL
uid                 = "Blake"
pwd                 = 'C:/some/other/file.txt'
connection          = "driver=<driver>;dbalias=alpha;uid=<uid>;pwd=<pwd>;"
case                = "nochange"
believeNRows        = TRUE
colQuote            = c("`", "'")
tabQuote            = '"'
interpretDot        = TRUE
DBMSencoding        = ""
rows_at_time        = 100
readOnlyOptimize    = FALSE

# Additional parameters for RODBC::sqlQuery.
errors              = TRUE
as.is               = TRUE
max                 = 0
buffsize            = 1000
nullstring          = NA_character_
na.strings          = c("NA", "-", "")
dec                 = "."
stringsAsFactors    = FALSE

# Parameters for SQRL.
aCollapse           = ','
autoclose           = TRUE
driver              = "{IBM DB2 ODBC DRIVER}"
interface           = "Z"
lCollapse           = "\n"
library             = "my/library/file.sqrl"
ping                = "select 1 from dual"
verbose             = FALSE
visible             = TRUE
prompt              = "Z"
retry               = TRUE
scdo                = TRUE
wintitle            = "(Zen)"

Commentary on Example File

This is a sample configuration file, exhibiting almost all parameters. In general, a file need not include all of these (default values are in place).

Parameters may be defined as the path to some other file. The driver and dsn parameters will take that path as their value. For all other parameters, a value will be read from within the file. Such files may contain only a single line with nothing but the value on it, or they may adhere to the full (multiple line) ‘parameter = value’ format (as above).

Configuration scripts are parsed and evaluated as R, but any expressions in which the final assignment is made via = (as opposed to <-) are interpreted as requests to set SQRL/RODBC parameter values, rather than R environment variables.

See Also

sqrlParams, sqrlSource

Examples

# Define a new source (not from file).
sqrlSource("Orac",
           "DBQ=StarOne;UID=Avon;PWD=<pwd>",
           "Driver={Oracle in OraDB18Home1}")

# Review its configuration (parameter values).
Orac("config")

# Create a file, containing only 'TRUE'.
file1 <- normalizePath(tempfile(), "/", FALSE)
writeLines("TRUE", file1)

# Create a file, containing named parameter values.
file2 <- normalizePath(tempfile(), "/", FALSE)
writeLines(c("dsn = 'Aristo'",
             "uid = 'Ensor'",
             "autoclose = TRUE",
             "as.is = FALSE"),
           file2)

# Create a configuration file, referencing the two above.
# Observe the use of temporary (non-parameter) variable 'x'.
file3 <- tempfile()
writeLines(c("aCollapse = ', '",
             paste0("verbose = \"", file1, "\""),
             "x <- 4",
             "max = sqrt(100 * x)",
             "as.is = TRUE",
             paste0("autoclose = '", file2, "'")),
           file3)
readLines(file3)

# Configure from the main (third) file.
Orac(config = file3)

# Alternative file-import forms.
Orac("config", file3)
Orac(paste("config", file3))

# Confirm imported values.
# Only 'autoclose' has been read from file2.
Orac("config")

# Import one parameter value from a file
# containing only a single unnamed value.
Orac(readOnlyOptimize = file1)
Orac("readOnlyOptimize")

# Import only a single specific parameter value
# from a file containing several named values.
Orac(uid = file2)
Orac("uid")

# Define and configure a new source from file.
sqrlSource("Caro", file2)
Caro("config")

# Configuration can also be performed from a named list,
# which could be generated by any R function or script.
Caro(config = list(autoclose = FALSE, max = 100))
Caro("config")[c("autoclose", "max")]

# Delete files.
unlink(c(file1, file2, file3))

SQRL documentation built on Sept. 21, 2022, 9:13 a.m.