Golang : Calculate entire request body length during run time

Problem:

You are trying to figure out what to fill into the number_of_bytes_in_entire_request_body field when making a http.NewRequest(). You need to calculate the entire request body as a requirement for the Content-Length header.

Solution:

From the https://golang.org/pkg/net/http/#Request type documentation :

// ContentLength records the length of the associated content.

// The value -1 indicates that the length is unknown.

// Values >= 0 indicate that the given number of bytes may

// be read from Body.

// For client requests, a value of 0 means unknown if Body is not nil.

ContentLength int64

We can derive the request body size(length) during run time from the Request.ContentLength. Therefore, to send the number of bytes in the entire request body as a header information, you can do it in such as way.

 request.Header.Add("Content-Length", strconv.FormatInt(request.ContentLength,10))

strconv.FormatInt() is to convert the int64 type to string type.

Hope this helps!

References:

https://www.socketloop.com/tutorials/golang-convert-cast-int64-to-string

https://golang.org/pkg/net/http/#Request