Reading/Parsing an iCalendar File (.ics)

[csharpusr]

Hello,
I'm looking for some C# code that loads a iCalendar file from a wesbite, loops through the .ics file and extracts the event details from each event in the file. I don't want to use aspose.icalendar or another one of the popular packages.

My ultimate goal is take the iCal data and import into a SQL Server database. I can handle the import to the database but I'm having trouble reading the iCalendar files from external website.

I've been able to load rss files in the past and pull the data within those files into a database. I don't see how loading a structured ical file would be that different.

Is my reasoning off?

Thanks.

[Plater]

I suppose if you can follow the RFC for it, parsing an .ics file should not be a problem. It seems reasonable to do.
I'm sure google probably does it, maybe they release some API on the matter?

What do you mean by reading the file from a website?
Like you want your application to go to some http:// address and get a file to parse?

[csharpusr]

I suppose if you can follow the RFC for it, parsing an .ics file should not be a problem. It seems reasonable to do.
I'm sure google probably does it, maybe they release some API on the matter?

What do you mean by reading the file from a website?
Like you want your application to go to some http:// address and get a file to parse?

Basically yes. I want to load an external icalendar file from a website and then take the data in the icalendar file and import it into a SQL server database.

I'm having issues trying to parse the ical file.

[Plater]

Well you can use HttpWebRequest on the serverside code to try and grab the iCal file from the internet address.

http://en.wikipedia.org/wiki/ICalendar

Looks pretty much like it is just name : value pairs?

[csharpusr]

Thanks for putting me on the right path. I'm grabbing the iCalendar file properly but I'm not sure how to get each event out of the file. I've read that regex could help but I've never used them before. ANy suggestions aor help?

Thanks.

Here's my code thusfar:

HttpWebRequest myRequest = (HttpWebRequest)WebRequest.Create("http://sports.yahoo.com/nfl/teams/cin/ical.ics");
myRequest.Method = "GET";
WebResponse myResponse = myRequest.GetResponse();
StreamReader sr = new StreamReader(myResponse.GetResponseStream(), System.Text.Encoding.UTF8);
string result = sr.ReadToEnd();
sr.Close();
myResponse.Close();
Console.WriteLine(result);

[Plater]

Well it should be in the format of

name1:value1
name2:value2
name3:value3
name4:value4
name5:value5
name6:value6
 

Just need to know how many to read for one "Event"

[csharpusr]

Here's a sample iCal file. The information between the BEGIN:VEVENT and END:VEVENT represents a single event. I need to grab all of the events in the file. Thanks so much for your help.

BEGIN:VCALENDAR
VERSION:2.0
METHOD:PUBLISH
X-WR-CALNAME:Baltimore Ravens Calendar (NFL)
PRODID:-//sports.yahoo.com//Baltimore Ravens Calendar (NFL)//EN
BEGIN:VEVENT
DTSTART;TZID=US/Pacific:20080907T100000
DTEND;TZID=US/Pacific:20080907T130000
SUMMARY:Cincinnati at Baltimore
UID:Baltimore Ravens Calendar (NFL)[e-mail]
SEQUENCE:0
COMMENT:Copyright 2006 (c) Yahoo!, Inc. All Rights Reserved.
DESCRIPTION:TV: CBS
DURATION:PT3H0M
DTSTAMP:20080612T112611
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=US/Pacific:20081102T100000
DTEND;TZID=US/Pacific:20081102T130000
SUMMARY:Baltimore at Cleveland
UID:Baltimore Ravens Calendar (NFL)[e-mail]
SEQUENCE:0
COMMENT:Copyright 2006 (c) Yahoo!, Inc. All Rights Reserved.
DESCRIPTION:TV: CBS
DURATION:PT3H0M
DTSTAMP:20080612T112611
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=US/Pacific:20081130T100000
DTEND;TZID=US/Pacific:20081130T130000
SUMMARY:Baltimore at Cincinnati
UID:Baltimore Ravens Calendar (NFL)[e-mail]
SEQUENCE:0
COMMENT:Copyright 2006 (c) Yahoo!, Inc. All Rights Reserved.
DESCRIPTION:TV: CBS
DURATION:PT3H0M
DTSTAMP:20080612T112611
END:VEVENT
END:VCALENDAR

[Curtis Rutland]

I'd parse it around newline characters for starters. Then you should have an array of each line. Then I'd loop through that array until I find a line that says: "BEGIN:VEVENT". Then, I'd grab the next 9 lines, splitting each around ":", and only keep the 2nd half. Do your insert and repeat.

This is how I'd do it, if I already had a text file. Just use your "result" string in place of my "ical" string.

FileStream fs = new FileStream(@"c:\dev\ical.txt", FileMode.Open, FileAccess.Read);
StreamReader sr = new StreamReader(fs);
string ical = sr.ReadToEnd();
char[] delim = { '\n' };
string[] lines = ical.Split(delim);
delim[0] = ':';
for (int i = 0; i < lines.Length; i++)
{
    if (lines[i].Contains("BEGIN:VEVENT"))
    {
        string[] eventData = new string[9];
        for (int j = 0; j < 9; j++)
            eventData[j] = lines[i + j + 1].Split(delim)[1];
        ///////////////////////////
        //Do your SQL INSERT here//
        ///////////////////////////
        i += 10;
    }
}
sr.Close();
 

This assumes that there are always nine fields associated with each event though. If there can be less, then this would fail. In that case you would have to check to see if each one is what it should be.

[csharpusr]

Awesome thanks for the posting. I'm able to download and parse the calendar data. One question - some iCalendar files have more or less than 9 values for each calendar event. How would go about just getting all of the information between the
BEGIN:VEVENT
END:VEVENT

One other question. This line grabs the data after the ":'.
eventData[j] = lines[i + j + 1].Split(delim)[1];

I also need to test on the filed names. When I declare a new string and do this:
eventDataHeader[j] = lines[i + j + 1].Split(delim)[0];

I'm getting this error: "The name "j" does not exist in the current context". I don;t understand why I'm getting this error.

Thank you guys so much for your help.

[Curtis Rutland]

1st question: Change the 2nd for loop to a while loop, and check each value to see if it is a END:VEVENT before splitting it and saving it. If it is, execute your sql with what you've got. You could also change eventData to an ArrayList, so you can dynamically change the size.

2nd question: Yes, that line does grab the data after the :. I don't really see a question here.

3rd question: j only exists inside the for loop that created it. It's called "scope." If you need to retain the value of j, you must declare it at the level you need to use it at.

Awesome thanks for the posting. I'm able to download and parse the calendar data. One question - some iCalendar files have more or less than 9 values for each calendar event. How would go about just getting all of the information between the
BEGIN:VEVENT
END:VEVENT

One other question. This line grabs the data after the ":'.
eventData[j] = lines[i + j + 1].Split(delim)[1];

I also need to test on the filed names. When I declare a new string and do this:
eventDataHeader[j] = lines[i + j + 1].Split(delim)[0];

I'm getting this error: "The name "j" does not exist in the current context". I don;t understand why I'm getting this error.

Thank you guys so much for your help.

[Plater]

You could create a NameValueCollection for each pairing you find to. Might make it easier to manipulate data once it's parsed into that object.

[csharpusr]

Here's another question. As I'm parsing the iCalendar file some of the events have additional ":" in them. For Instance, here's an example of a description in an event:

DESCRIPTION:Regular Registration/Postmark Date:\nSeptember 19\, 2003\nLa
te Registration Period/Fee + Late Fee: September 20-Oct. 3\, 2003\n\nFo
r info on registering after the late registration period go to: \n<http
://www.act.org/aap/regist/standbytest.html>\n\nTo confirm that this test
date is available outside of the 50 US States go to: http://www.act.or
g/aap/regist/outside.html

The script parses out the ":" in the URLs as a new line. I need to grab the entire contents of the data within the description field into a single variable. Any ideas?

Again, thanks so much for your help.

[Plater]

Perhaps do a first indexOf(":") and then everything after that is the value?

[Curtis Rutland]

Here's another question. As I'm parsing the iCalendar file some of the events have additional ":" in them.
Again, thanks so much for your help.

Do the Split to a new String[]. Make another string called temp or something. Then loop through the array, starting with index 1 and ending with Length-1, appending each of them to temp, and if it isn't the last one, append a ":".
something like this: (using my original code. you'll have to fit this into the way you modified yours)

for (int j = 0; j < 9; j++)
{
    string[] line = lines[i + j + 1].Split(delim);
    string temp = "";
    for(int k=1; k<line.Length; k++)
    {
        if(k<line.Length - 1)
            temp += line[k] + ":";
        else
            temp += line[k];
    }
    eventData[j] = temp;
}
 

[csharpusr]

Cool that's working great. The only other issue I'm having is that the new lines in the description are being parsed out seperatly. So instaed of gathering all of the data after the description I'm getting the first line. Does that make sense?

Again, I can't thank you guys enough for all of your help.

[Curtis Rutland]

Cool that's working great. The only other issue I'm having is that the new lines in the description are being parsed out seperatly. So instaed of gathering all of the data after the description I'm getting the first line. Does that make sense?

Again, I can't thank you guys enough for all of your help.

So there are newline chars in the file aside from separating each pair? Wow, that's tough. Can't think of an easy fix off the top of my head.

[csharpusr]

Yep, it's a bugger. According to the iCalendar spec data needs to be wrapped to the next line if it is over a certain length. The next line has a open space before the beginning of the text. So here's an example:

DESCRIPTION:Regular Registration/Postmark Date:\ La
te Registration Period/Fee + Late Fee: September 20-Oct. 3\, 2003\n<http
://www.act.org/aap/regist/standbytest.html>\n\nTo confirm that this test

The sample above should have a space before "te Registration..." and "://www.act.org..."

[Curtis Rutland]

Yep, it's a bugger. According to the iCalendar spec data needs to be wrapped to the next line if it is over a certain length. The next line has a open space before the beginning of the text. So here's an example:

DESCRIPTION:Regular Registration/Postmark Date:\ La
te Registration Period/Fee + Late Fee: September 20-Oct. 3\, 2003\n<http
://www.act.org/aap/regist/standbytest.html>\n\nTo confirm that this test

The sample above should have a space before "te Registration..." and "://www.act.org..."

Well, I guess you can check for a space character at the beginning of each line, and if there is one, append it's data to the last one.

Other than that, good luck!