How to escape the url encoding in URLWRITE

Hi

I've encountered a slight problem trying to use URLWRITE with 'get' parameters.

keyStr = 'Fmjtd%7Cluubnuur2h%xxxxxxxxxxx'; % not a real key
params = {'key' keyStr};

Now with appropriate url and filename I try:

[~,status] = urlwrite(url,filename,'get',params);

But URLWRITE calls java.net.URLEncoder.encode on the params so %'s are turned into %25, and of course the key fails.

How can I escape the url encoding? I've tried '%%' and '\%' but neither work.

Any ideas appreciated.

Neil

[Walter Roberson]

Is the %7C intended to be interpreted on the other end as literally '%' '7' 'C', or is it intended that the other end decode it to character #252 ?

[Neil Caithness]

Yes, the content of the key needs to be passed literally, without url encoding.

Answer 1

[Friedrich]

Hi,

you can't. Look at the rules which are applied:

"All other characters are unsafe and are first converted into one or more bytes using some encoding scheme. Then each byte is represented by the 3-character string "%xy", where xy is the two-digit hexadecimal representation of the byte."

Seems like you need your own customized version of urlwrite here.

[Neil Caithness]

Thanks. Yes, I've written a custom URLWRITE, if the parameter name is 'key' then skip the url encoding. Very hacky!

I guess the receiving web-service is not standards compliant. In this case http://open.mapquestapi.com/staticmap/wizard.html which insists that unsafe characters in the key are not encoded.

[Neil Caithness]

I was just checking what Mapquest say in their API documentation and they do have this line - 'Please note that these key/value pairs must be properly URL-encoded.' I'm sure they understand more about this stuff than I do, but if I inset a raw key into their demo URLs it works, if I substitute %25 for each % (just as URLWRITE does) then it doesn't work.

So my question is: Is URLWRITE doing what is proper, and in this case I go with a hacky solution?

[Walter Roberson]

I would substitute char(252) for the %7C in your string, and then let the url encoder transform it to %7c

[Neil Caithness]

Walter, of course. Nice suggestion. Thanks