Codepolice.net » C#

IN queries with LINQ to SQL

Ola — Tue, 01 Jun 2010 13:33:12 +0000

This is another awesome feature in LINQ to SQL that i always forget about. Sometimes you have an array of strings or any other type and want to query the database for all values that have one of the values in the array.

string platform = "windows|linux";
string[] platformList = platform.Split('|');
itemQuery = from m in itemQuery
from p in m.PlattformItemRelations
where platformList.Contains(p.Plattform.Text.ToLower())
select m;

Ain’t that a beauty? I got this tip from Ron Connery so all the kudos to him.

Create a comma separated list with LINQ in C#

Ola — Tue, 20 Apr 2010 13:29:59 +0000

For some reason I always forget that you do not do .Join on your actual string array. So i might as well write it down here so i never forget about this again.

string mycommalist = string.Join(",", alternatives.Select(x=>x.Item.Name).ToArray())

Convert String Array to Int Array and vice versa in C#

Ola — Sat, 07 Nov 2009 15:35:17 +0000

Sometimes you want to convert arrays back and forth. This is to nice extension methods to convert a int array into a string array and vice versa.

public static class ExtensionMethods {

  public static string[] ToStringArray(this int[] intArray) {
   return Array.ConvertAll(intArray, delegate(int intParameter) { return intParameter.ToString(); });
  }

  public static int[] ToIntArray(this string[] strArray) {
   return Array.ConvertAll(strArray, delegate(string intParameter) { return int.Parse(intParameter.ToString()); });
  }
}

file_get_contents() in asp.net/C#

Ola — Fri, 13 Feb 2009 11:25:59 +0000

The URL shortening service http://bit.ly has a really simple and convient API that lets just get a short url like this.

http://bit.ly/api?url=http://www.myreallylong.com/url/with/lots?of=crap

I’ve used this in a wordpress installation with PHP before and there i could just do.

$twitter_url .= file_get_contents('http://bit.ly/api?url=' . get_permalink());

Simple and clean. But today i wanted to do the same thing with asp.net and found myself kind of lost. At last i came up with this, not as simple solution. But it works.

string shortUrl = new StreamReader(WebRequest.Create("http://bit.ly/api?url=http://fragor.ohsohightech.se" + Url.Action("Question", new { number = question.Number, title = question.Title.ConvertTextToUrl() })).GetResponse().GetResponseStream()).ReadToEnd();

Create a tag cloud with limited amout of tags in ASP.NET and LINQ

Ola — Tue, 14 Oct 2008 15:13:12 +0000

Today i built a Tag cloud for my new site. I found this great article about on how to do it with LINQ and C#. But i missed some features. Especially how to limit the number of tags that was shown. So if you read that article and then have a look at this code if you have the same problem as me.

var tagSummary = (from ti in db.TagItemRelations
group ti by ti.Tag.Text into tagGroup
select new {
Tag = tagGroup.Key,
TagFrequency = tagGroup.Count()
}).OrderByDescending(x=>x.TagFrequency).Take(20);

int maxTagFrequency = (from t in tagSummary select t.TagFrequency).Max();

var tagCloud = (from ti in tagSummary
select new TagCloudItem {
Tag = ti.Tag,
Weight = (double)ti.TagFrequency / maxTagFrequency * 100
}).OrderBy(x=>x.Tag);

The main difference between my code and the code in the article is that i have slightly more complex data model (should not matter) and that i make the second query against the “result” from the first query. This allow me to first order by popularity and then in alphabetic order.

Please leave a comment if there is any better way to do this or if you have any questions.