I must be really dense, I know RCurl provides a POST capability, but I
don't see how this allows "interaction". Suppose the example actually
worked, which it does not. (Unfortunately many of the examples in RCurl
seem to be marked \dontrun{} or disabled with some if() condition.) When
you post to a page like this you will often get something back that has
a dynamically generated URI, and you will need to post more information
to that page. But how do you find out the URI of that next dynamically
generated page? Even when you know what you will need to post, you need
the URI to do it. If RCurl provided interaction you would be able get
the URI so you could post to the next page. Maybe you can do that, but I
have not discover how. If you know how, I would appreciate a real
working example.
Paul
On 12-10-31 12:14 PM, jose ramon mazaira wrote:
I'd like to make you note that I've discovered that package RCurl
already provides a utility that allows interaction via POST requests
with servers. In fact, the FAQ for RCurl contains specifically an
example with an aspx page:
x = postForm("http://www.fas.usda.gov/psdonline/psdResult.aspx",
style = "post",
.params = list(visited="1",
lstGroup = "all",
lstCommodity="2631000",
lstAttribute="88",
lstCountry="**",
lstDate="2011",
lstColumn="Year",
lstOrder="Commodity%2FAttribute%2FCountry"))
Check this link: http://www.omegahat.org/RCurl
However, I think that it would be more useful to automate the
interaction with servers retrieving automatically the name-value pairs
required by the server (parsing the page source code) instead of
examining in each web page the appropiate fields.
2012/10/30, Paul Gilbert <pgilbert902 at gmail.com>:
Jose
As far as getting to the data, I think the best way to do this sort of
thing would be if the site supports a SOAP or REST interface. When they
don't (yet) then one is faced with clicking through some pages. Python
or Java is one way to automate the process of clicking through the
pages. I don't know how to do that in R, but would like to know if it is
possible.
But, I guess I was confused about the part you want to improve. What I
have works fairly smoothly parsing and passing back JSON data, converted
from a csv file, into R. The downside is that this approach requires
more than R to be installed on the client machine. But if the object you
get back is ASPX, then you either need to parse it directly, or convert
it to JSON, or something else you can deal with. I suspect that will be
fairly specific to a particular web site, but I don't really know enough
about ASPX to be sure.
Paul
On 12-10-30 01:12 PM, jose ramon mazaira wrote:
Thanks for your interest, Paul.
I've checked the source code of TSjson and I've seen that what it does
is to call a Python script to retrieve the data. In fact, I've already
done this with Java using the URLConnection class and sending the
requested values to fill the form.
However, I think it would be more useful to open a connection with R
and to send the requested values within R, and not through an external
program.
The application I've designed, like yours, is also page-specific
(i.e., designed for
http://cxa.gtm.idmanagedsolutions.com/finra/BondCenter/AdvancedScreener.aspx),
but I think that our applications would be more powerful if they were
able to parse the name-value pairs generated from ASPX (or of any
other dynamically generated web page) and ask the user to select the
appropiate values.
2012/10/30, Paul Gilbert <pgilbert902 at gmail.com>:
I think RHTMLForms works if you have a single form, but I have not
been
able to see how to use it when you need to go through a sequence of
dynamically generated forms (like you can do with Python mechanize).
Paul
On 12-10-30 09:08 AM, Gabriel Becker wrote:
I haven't used it extensively myself, and can't speak to it's current
state but on quick inspection RHTMLForms seems worth a look for what
you
want.
http://www.omegahat.org/RHTMLForms/
~G
On Tue, Oct 30, 2012 t 5:38 AM, Paul Gilbert <pgilbert902 at gmail.com
<mailto:pgilbert902 at gmail.com>> wrote:
I don't know of an easy way to do this in R. I've been doing
something similar with python scripts called from R. If anyone
knows
how to do this with just R, I would appreciate hearing too.
Paul
On 12-10-29 04:11 PM, jose ramon mazaira wrote:
Hi. I'm trying to write an application to retrieve
financial
data
(specially bonds data) from FINRA. The web page is served
dynamically
from an asp.net <http://asp.net> application:
http://cxa.gtm.__idmanagedsolutions.com/finra/__BondCenter/AdvancedScreener.__aspx
<http://cxa.gtm.idmanagedsolutions.com/finra/BondCenter/AdvancedScreener.aspx>
I'd like to know if it's possible to fill dynamically the
web
page
form from R and, after filling it (with the issuer name),
retrieve the
web page, parse the data, and covert it to appropiate R
objects.
For example, suppose I want to search data for AT&T bonds.
I'd
like to
know if it's possible, within R, to fill the page served
from:
http://cxa.gtm.__idmanagedsolutions.com/finra/__BondCenter/AdvancedScreener.__aspx
<http://cxa.gtm.idmanagedsolutions.com/finra/BondCenter/AdvancedScreener.aspx>
select the "corporate" option and fill with AT&T the field
for
"Issuer
name", ask the page to display the results, and retrieve
the
results
for each of the bonds issued by AT&T (for example:
http://cxa.gtm.__idmanagedsolutions.com/finra/__BondCenter/BondDetail.aspx?ID=__MDAxOTU3Qko3
<http://cxa.gtm.idmanagedsolutions.com/finra/BondCenter/BondDetail.aspx?ID=MDAxOTU3Qko3>)
and parsing the data from the web page.
Thanks in advance.