CODEWITHSUNDEEP
c#linqlinq-to-sql
Palmi
Palmi

Reputation: 2521

Check for value in delimitted field via LINQ

I have a Db table with a csv field called "Line". There are several values in the field separated by semicolons.

I am trying to find a LINQ expression to check if there is any row where the second value in the "Line" field has a specific value.

Something like:

if (dbContext.Test.Any(t => Array.IndexOf(t.Line.Split(';'), value) = 1))
{
Do something ...                          
}

Example:

Line = "value1;apple;value3;value4"
if (dbContext.Test.Any("second value in Line field equals 'apple'"))
{
Do something ...
}

What's the most straight-forward and concise way to do this?

Upvotes: 3

Views: 360

Answers (3)

D Stanley
D Stanley

Reputation: 152626

Since you appear to be using a DbContext and there's no mechanism to translate splitting a string or searching by index you'll need to get more data than necessary, then filter in linq-to-objects. You could to an initial basic filter to limit the number of rows coming back, but you'll need to do the remaining filtering in-memory:

var queryEF = dbContext.Test
                       .Where(t => t.Line.Contains(";" + value" + ";");

var queryMemory = queryEF.AsEnumerable()   // shift to Linq-to-Objects
                         .Where((t => Array.IndexOf(t.Line.Split(';'), value) == 1);

if (queryMemory.Any())
{
    //Do something ...
}

Upvotes: 1

TVOHM
TVOHM

Reputation: 2742

So as I understand it, your table (dbContext) contains a collection of rows (Test)?

You can use 'where' to reduce that collection down to only elements that meet the condition (in this case, I split the string by the semi-colon and see if the second string is equal to apple. 'Any' will then return true if there were one or more matches.

        if(dbContext.Test.Where(x => x.Line.Split(';')[1] == "apple").Any())
        {
            // Do the thing
        }

Upvotes: 0

BendEg
BendEg

Reputation: 21108

If you just want to check the value Linq is a simple method for this.

Just do the following:

  1. Take the column
  2. Splitt it's content
  3. If there is more than one Element in the splitted list continue
  4. Proof whether the second element is what you are looking for.

You should consider to normalize your data, because of storing redundant/unnormalized data could cause other problems.

EDIT

Ok, working with linq in this case is not as easy as i thought, because we do not have any index information. This is easy and should work:

string line = "value1;apple;value3;value4";
string[] splitted = line.Split(new char[] { ';' });
if (splitted.Length > 1 && splitted[1] == "apple")
{
    Console.WriteLine("APPLE!");
}

Upvotes: 0

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