CODEWITHSUNDEEP
c#linq
pekcheng
pekcheng

Reputation: 364

LINQ select using .split()

I have a comma separated string stored in database.

E.g.: record1 = "1,3,5,7,9,10" and record2 = "4,5,10"

And I have a given information, E.g.: 1.

I have to select the record using LINQ that contains the given info of 1.

The result returned should be record1.

If I were to use .contains() solely, it's not accurate as record2 will be returned as well.

How can I achieve that? Is it possible to achieve that in a single LINQ query?

Thanks for advise !

Upvotes: 1

Views: 3677

Answers (4)

brainless coder
brainless coder

Reputation: 6430

First of all I would like to mention what @Tim Schmelter said -

Have you noticed already that the real problem is your creepy datamodel? Use a table with real records instead of a column with a comma separated string.

It is not a good practice to use a datamodel where you need string split match. Because it leads to inefficient systems and not to mention slow queries. But yet, if you really need a solution why not try this -.

There are four occasions where you will get a match,

  1. A prefix match - starting with
  2. Inner Match - contains with
  3. Suffix Match - ends with
  4. The only match - only one item and this is it

considering the scenario I am suggesting the solution below - 

s is the value looking for say "1"
string prefixMatch = s + ",";
string suffixMatch = "," + s;
string innerMatch = "," + s + ",";
string record = <dbRecords>.FirstOrDefault(r=> r.StartsWith(prefixMatch) ||
r.Contains(innerMatch) || r.EndsWith(suffixMatch) || 
(!r.Contains(",") && r == s));

The reason for such a detailed query is to keep your memory utilisation less and letting the SQL query do the hard work of finding the results because this query will support LINQ-to-SQL conversion.

Upvotes: 1

Rajeev Ranjan
Rajeev Ranjan

Reputation: 1036

Instead of searching 1 you can try 1,(1 and comma combined) for searching in Contains in linQ

Upvotes: 0

Gleb
Gleb

Reputation: 1432

If i understand you correctly, you need as result record that contains "1". So you can use:

private bool GerRecord(string record)
{
    string[] arr=record.Split(',');

    return arr.Contains("1");
}

Upvotes: 0

CodingIntrigue
CodingIntrigue

Reputation: 78525

With a single LINQ-to-objects query:

string[] records = new[] { record1, record2 };
string record = records.FirstOrDefault(r => r.Split(',').Any(s => s == "1"));

Demo

Upvotes: 6

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