Loadrunner How To Read a File into a Parameter

Here is a method for reading the contents of a file into a loadrunner parameter.  This can be useful for various situations such as reading XML or JSON requests from file, reading data, etc.

Script



//#include <stdio.h>
#define SEEK_SET 0 /* beginning of file. */
#define SEEK_CUR 1 /* current position. */
#define SEEK_END 2   /* end of file */


Action()
{
long infile; // file pointer
char *buffer; // buffer to read file contents into
char *filename = "test.txt"; // file to read
int fileLen; // file size
int bytesRead; // bytes read from file
// 
// open the file
infile = fopen(filename, "rb");
if (!infile) {
  lr_error_message("Unable to open file %s", filename);
  return;
}


// get the file length
fseek(infile, 0, SEEK_END);
fileLen=ftell(infile);
fseek(infile, 0, SEEK_SET);
lr_log_message("File length is: %9d bytes.", fileLen);


// Allocate memory for buffer to read file
buffer=(char *)malloc(fileLen+1);
if (!buffer) {
  lr_error_message("Could not malloc %10d bytes", fileLen+1);
  fclose(infile);
  return;
}


// Read file contents into buffer
bytesRead = fread(buffer, 1, fileLen, infile);
if (bytesRead != fileLen) 
{
  lr_error_message("File length is %10d bytes but only read %10d bytes", fileLen, bytesRead);
}
else
{
  lr_log_message("Successfully read %9d bytes from file: ", bytesRead);
}
fclose(infile);


// Save the buffer to a loadrunner parameter
lr_save_var( buffer, bytesRead, 0, "fileDataParameter");
free(buffer);
lr_log_message("File contents: %s", lr_eval_string("{fileDataParameter}"));
}




Step by Step Walk Through
Constants needed for fseek calls, also available in stdio.h:

#define SEEK_SET 0 /* beginning of file. */
#define SEEK_CUR 1 /* current position. */
#define SEEK_END 2   /* end of file */


Open file:

infile = fopen(filename, "rb");
if (!infile) {
lr_error_message("Unable to open file %s", filename);
return;
}


Get file length:

        fseek(infile, 0, SEEK_END);
fileLen=ftell(infile);
fseek(infile, 0, SEEK_SET);
lr_log_message("File length is: %9d bytes.", fileLen);


Allocate memory to read file into:

buffer=(char *)malloc(fileLen+1);
if (!buffer) {
lr_error_message("Could not malloc %10d bytes", fileLen+1);
fclose(infile);
return;
}


Read file into memory:

bytesRead = fread(buffer, 1, fileLen, infile);
if (bytesRead != fileLen) 
{
lr_error_message("File length is %10d bytes but only read %10d bytes", fileLen, bytesRead);
}
else
{
lr_log_message("Successfully read %9d bytes from file: ", bytesRead);
}

Close file handle:
fclose(infile);


Save the file to a loadrunner parameter:

lr_save_var( buffer, bytesRead, 0, "fileDataParameter");
free(buffer);
        lr_log_message("File contents: %s", lr_eval_string("{fileDataParameter}"));


File
The following is an example input file "test.txt" which would be located in the script directory (<loadrunner installation directory>/scripts/<scriptname>/test.txt:


First line of file.
<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/"><soap:Body><Node>Data</Node></soap:Body></soap:Envelope>
Last line of file

Console Output

Running Vuser...
Starting iteration 1.
Starting action Action.
File length is:       168 bytes.
Successfully read       168 bytes from file: 
File contents: First line of file.
<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/"><soap:Body><Node>Data</Node></soap:Body></soap:Envelope>
Last line of file
Ending action Action.
Ending iteration 1.
Ending Vuser...