How do I read, update and replace a "String body" field in a web test from a plugin?

Question

My recorded web performance test has several "String body" fields and I need to modify their contents at run time from within a web test request plugin.

The "String body" field is not directly available from the various fields and subfields of the PreRequestEventArgs.

How do I read out the "String body" field into a string and, after modifying it, write it back?

Answer 1

To read out the "String body" field, cast the request body to a StringHttpBody which makes the string available. To write it back, create a new StringHttpBody object to contain the updated string, then write it into the request.

Using a plugin I need to modify the "String body" field of a request in a web performance test. I can access the contents using the following code:

public override void PreRequest(object sender, PreRequestEventArgs e)
{
    if ( e.Request.Body == null ) { return; }
    StringHttpBody httpBody = e.Request.Body as StringHttpBody;
    if ( httpBody == null ) { return; }
    string body = httpBody.BodyString;

    string updatedBody = UpdateBody(body);

    StringHttpBody newBody = new StringHttpBody();
    newBody.BodyString = updatedBody;
    e.Request.Body = newBody;
}