Datatable search by LINQ to avoid duplication

Question

I have a column in dataTable with blank rows

Column1
A
B
C

D

E

I need to set if exist and to avoid adding, but blank rows should not be counted. Only rows with data should be in the (if exists). Thanks

 bool exists = dt.Select().ToList().Exists(row => row["column1"].ToString() == txtbox)



if(exists == true)
{}
else

// it includes blank so it goes to true, which I need is blank rows should not be included.

How can a blank row be included if you search for "search field"? Just handle the case that the user didn't enter anything into the search TextBox. — Tim Schmelter, Sep 12 '18 at 08:10
that search field is a textbox that can be empty or whitespaces. So first I need to collect all the rows withour blank then in that collection I will check if exist based on the search fields. But I don't know the code — Alphatrix, Sep 12 '18 at 08:12
Possible duplicate of [Avoiding duplicate code in Linq Select method](https://stackoverflow.com/questions/34649878/avoiding-duplicate-code-in-linq-select-method) — Pvria Ansari, Sep 12 '18 at 08:12
Can you provide a meaningful example? _"search field can be empty or whitespaces"_ .. _"...collect all the rows without blanks"_ .. _"I will check if exist based on the search field"_ Doesn't make sense. — Tim Schmelter, Sep 12 '18 at 08:13
bool exists = dt.Select().ToList().Exists(row => row["column1"].ToString() == txtbox), I already had this code but it includes blank string "". I need to bypass that "" blank string. — Alphatrix, Sep 12 '18 at 08:14
@Alphatrix: edit your question and provide a meaningful sample with input, data and expected result. — Tim Schmelter, Sep 12 '18 at 08:16
I don't understand why can't you add the condition in the `Exists` lambda? Also, why does it return false? why would the extra rows bother if you use `Exists`? it should return true. — Ofir Winegarten, Sep 12 '18 at 08:23
So, if the only thing missing is check for empty string of the txtbox, then add it, instead of trying to reduce rows. Which you can do either. — Ofir Winegarten, Sep 12 '18 at 08:27

Antoine V · Accepted Answer · 2018-09-12T08:43:54.927

1

var lignesNonContainEmptyString = dt.Select()
                   .Where(row => row["column1"] != null 
                                && row["column1"].ToString() == txtbox 
                                && !string.IsNullOrEmpty(row["column1"].ToString()))

bool exists = lignes.Count() != 0;

OR

bool exists = dt.Select()
                       .Any(row => row["column1"] != null 
                                    && row["column1"].ToString() == txtbox 
                                    && !string.IsNullOrEmpty(row["column1"].ToString()))

edited Sep 12 '18 at 08:43

answered Sep 12 '18 at 08:17

Antoine V

6,998
2
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bool exists = dt.Select().ToList().Exists(row => row["column1"].ToString() == txtbox), this code already work but it does not support blank rows, I need to bypass those blank rows, and it should return true or false – Alphatrix Sep 12 '18 at 08:24
Wow, thanks it really worked and saved a lot of time. – Alphatrix Sep 12 '18 at 08:38
Instead of `lignes.Count() != 0`, I like `Lines.Any()`. Readable and more efficient. – Drag and Drop Sep 12 '18 at 08:39
1

`dt.Select().ToList()` please not! `DataTable` is an in-memory collection that can be queried with LINQ(`AsEnumerable()`). `DataTable.Select` will iterate all rows and create a new `DataRow[]`. `ToList()` will iterate all rows and create a `List(Of DataRow)`. Instead of `Exists` you can use `Any`. – Tim Schmelter Sep 12 '18 at 08:42
@TimSchmelter, I see a bug in the matrix. Same comment same author :) – Drag and Drop Sep 17 '18 at 15:00

Ofir Winegarten · Answer 2 · 2018-09-12T08:45:01.823

You would like to return false if the textbox is empty, so add the condition for the textbox.

bool exists = !string.IsNullOrWhiteSpace(txtbox)
              && dt.Select().ToList()
                   .Exists(row => row["column1"].ToString() == txtbox)

By the way, instead of using .Select().ToList(), you can add a reference to System.Data.DataTableExtensions and use the Extension AsEnumerable:

dt.AsEnumerable().Any( .....

score 0 · Answer 3 · edited Feb 02 '21 at 11:15

0

this code can help you

from a in list where ( Column1 != null || Column1 != "")
&& Column1 == searchfield
select a

edited Feb 02 '21 at 11:15

Mahyar Mottaghi Zadeh

1,178
6
18
31

answered Sep 12 '18 at 08:14

Reza Faghani

141
1
10

bool exists = dt.Select().ToList().Exists(row => row["column1"].ToString() == txtbox). I need to modify this code, becuase it includes the blank input – Alphatrix Sep 12 '18 at 08:15

Gauravsa · Answer 4 · 2018-09-12T08:24:21.800

0

How about this: non linq way

bool DataTableNonEmptyCount()
{
int count =0;
foreach (DataColumn col in row.Table.Columns)
    if (!row.IsNull(col))
      count ++;

  return count;
}

This will return a count of all non null row in column.

edited Sep 12 '18 at 08:24

answered Sep 12 '18 at 08:19

Gauravsa

6,330
2
21
30

score 0 · Answer 5 · answered Sep 12 '18 at 08:45

Based on Thierry's answer, you can also use the Any(predicate) syntax:

var existsLineWithoutEmptyString = 
             dt.AsEnumerable()
               .Any(row => row["column1"] != null 
                           && row["column1"].ToString() == txtbox 
                           && !string.IsNullOrEmpty(row["column1"].ToString()))

Datatable search by LINQ to avoid duplication

5 Answers5