Using LINQ with flat text files

Question

In the past I have found the "Microsoft Text Driver" a great answer to some programming jobs.

 

(For those who haven't used it:  This is a driver that connects directly to flat files (comma separated or whatever) and allows them to be handled like a database, including SQL queries and writing data.  The relations etc. are defined in a file called "schema.ini".)

 

I'm currently looking at a job where LINQ against flat files would be a very good approach.

 

(There is only ever one user, if the data were imported into a dB it would likely be dumped again immediately...)

 

My search has not shown anybody doing this sort of thing with LINQ.

 

Is there an existing way to do this?

Answer 1

Hi MikeGale,

As far as I know, LINQ can query some .Net containers and collections, such as list generic class, please check the code snippet below.

Code Snippet

var aList = new List<FieldContainer>

            {

                new FieldContainer("a1"),

                new FieldContainer("a2"),

                new FieldContainer("a3"),

                new FieldContainer("a4"),

                new FieldContainer("a5")

            };

  var r1 = from a in aList

                     where a.Text=="a1"

                     select a;

 

            FieldContainer value1 = null;

            foreach (var q1 in r1)

                value1 = q1;

 

Code Snippet

public class FieldContainer

    {

        private string text;

        public string Text

        {

            get

            {

                return this.text;

            }

            set

            {

                this.text = value;

            }

        }

 

        public FieldContainer(string text)

        {

            Text = text;

        }

}

 

 

And you put the plain text to the list which wrapped by a custom class type.

Regards,

Xun

 

Answer 2

No that's not what I'm thinking about.

 

I'd like to link up to a set of files, described in a scema.ini and treated as if they were a relational database.

 

It was available in past MS database technologies and extremely useful (where it fits).

 

Answer 3

This might do the trick:

 

http://www.codeproject.com/KB/linq/LINQtoCSV.aspx

 

Anders

 

Answer 4

Thanks Anders.

 

I have just completed some tests of LINQToCSV.

 

It does indeed do the job.

 

The project was done using SQL Server, so I took some parts of it, made them into csv's, wrote a test app. to exercise them (C#) including joins and some simple LINQ queries.  When that worked I converted it into VB 9 and ran it there.  (There are a few differences but it all worked.  GREAT.)

 

(I see the article was published 2 days after I asked the question.  Serendipity?)

 

I'm impressed that you have the time to check these fora.  Thanks.