How to assign value empty when string is null in C#

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I have taken parameters for a command and assigning gridview rows as values.When the grid view row is null,it shows error 'Object Reference not set to an instance'.I know how to assign values using variable in try block.But i want to give like this.Is there any method to convert that values to empty strings in C#.

What I have tried:

C#

cmdTemp.Parameters.AddWithValue("@comment_NAME30", row.Cells[0].Value.ToString());
cmdTemp.Parameters.AddWithValue("PRODUCT_NO", row.Cells[1].Value.ToString());
cmdTemp.Parameters.AddWithValue("@PRODUCT_NAME", row.Cells[2].Value.ToString());
cmdTemp.Parameters.AddWithValue("@QTY", row.Cells[3].Value.ToString());
cmdTemp.Parameters.AddWithValue("@UOM", row.Cells[4].Value.ToString());
cmdTemp.Parameters.AddWithValue("@PRICE", row.Cells[5].Value.ToString());
cmdTemp.Parameters.AddWithValue("@ITEM1_NO", row.Cells[6].Value.ToString());
cmdTemp.Parameters.AddWithValue("@DISCOUNT_PC", row.Cells[7].Value.ToString());
cmdTemp.Parameters.AddWithValue("@AMOUNT", row.Cells[8].Value.ToString());
cmdTemp.Parameters.AddWithValue("@SC_NO", row.Cells[10].Value.ToString());
cmdTemp.Parameters.AddWithValue("@GL_CODE", row.Cells[11].Value.ToString());
cmdTemp.Parameters.AddWithValue("@PROJ_NO", row.Cells[12].Value.ToString());
cmdTemp.Parameters.AddWithValue("@Gp_NO", row.Cells[13].Value.ToString());
cmdTemp.Parameters.AddWithValue("@WH_NO", row.Cells[14].Value.ToString());
cmdTemp.Parameters.AddWithValue("@Sales_exempt", row.Cells[15].Value.ToString());
cmdTemp.Parameters.AddWithValue("@FACTOR", row.Cells[16].Value.ToString());
cmdTemp.Parameters.AddWithValue("@Category", row.Cells[18].Value.ToString());
cmdTemp.Parameters.AddWithValue("@IMPORTED_FROM_NO", row.Cells[19].Value.ToString());
cmdTemp.Parameters.AddWithValue("@IMPORTED_FROM", row.Cells[20].Value.ToString());
cmdTemp.Parameters.AddWithValue("@GST_Amt", row.Cells[23].Value.ToString());
cmdTemp.Parameters.AddWithValue("@DISCOUNT_PC_2", row.Cells[24].Value.ToString());
cmdTemp.Parameters.AddWithValue("@Ref_No", row.Cells[25].Value.ToString());
cmdTemp.Parameters.AddWithValue("@GL_DESC", row.Cells[27].Value.ToString());
cmdTemp.Parameters.AddWithValue("@PRODUCT_NAME_LONG", cfs.singlequotconver(strdesc));
cmdTemp.Parameters.AddWithValue("@CREATED_BY", uid.ToString());
cmdTemp.Parameters.AddWithValue("@DATE_CREATED", cfs.sqldateconverion());
cmdTemp.Parameters.AddWithValue("@Deleted", "False");
cmdTemp.Parameters.AddWithValue("@INV_NO", ddl_Inv.Text);
cmdTemp.Parameters.AddWithValue("@Transfer", "U");
cmdTemp.Parameters.AddWithValue("@TICK", "C");
cmdTemp.Parameters.AddWithValue("@ID", strInvId);
cmdTemp.Parameters.AddWithValue("@AC_NO", cfs.singlequotconver(txt_Custcode.Text));
cmdTemp.Parameters.AddWithValue("@AC_NAME", cfs.singlequotconver(txt_Cus_Name.Text));
cmdTemp.Parameters.AddWithValue("@ITEM10", cfs.singlequotconver(LineNo));
cmdTemp.Parameters.AddWithValue("@invNo_user", ddl_Inv.Text + uid.ToString());
cmdTemp.Parameters.AddWithValue("@AVERAGE_COST", cfs.get_data("select distinct AVERAGE_COST from PRODUCT where PRODUCT_NO='" + strpcode + "'"));
cmdTemp.Parameters.AddWithValue("@LP_COST", cfs.get_data("select distinct LP_COST from PRODUCT where PRODUCT_NO='" + strpcode + "'"));
cmdTemp.Parameters.AddWithValue("@STD_COST", cfs.get_data("select distinct STD_COST from PRODUCT where PRODUCT_NO='" + strpcode + "'"));
cmdTemp.Parameters.AddWithValue("@QTY_UNFILLED", strqtyfilled);
cmdTemp.Parameters.AddWithValue("@DATETIME", cfs.sqldateconverion(txt_trans_Date.Value));
cmdTemp.Parameters.AddWithValue("@Batch_No", batchno);
cmdTemp.Parameters.AddWithValue("@Expiry_Date", Expirydate);
cmdTemp.Parameters.AddWithValue("@PRINT_ITEM", printitem);
cmdTemp.Parameters.AddWithValue("@QTY_BILLED", Prodqty);
cmdTemp.Parameters.AddWithValue("@ITEM6_NO", Prodqty);
cmdTemp.Parameters.AddWithValue("@ITEM7_NO", pri);
cmdTemp.Parameters.AddWithValue("@ITEM8_NO", net);

Posted 20-Nov-16 20:25pm

TarunKumarSusarapu

Updated 21-Nov-16 2:39am

#realJSOP

v2

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Midi_Mick · Answer 1 · 2016-11-20T21:16:00

The new ?? operator is available for this type of operation. If the value on the left is null, it will return the value on the right. There is also a similar ?. operator, which does not call the property on the right if the value on the left is null, but returns null instead.

So, if you are sure that the input variable is a string, you can just pass

C#

string result = value ?? "";

If it is an unknown type object

C#

string result = value?.ToString() ?? "";

OriginalGriff · Answer 2 · 2016-11-20T20:31:00

Use the null-coalescing operator:

C#

private string AlwaysAString(object o) { return o.ToString() ?? ""; }

[edit]Bah! No, that'll throw a null reference exception...

C#

private string AlwaysAString(object o)
    {
    if (o != null) return o.ToString();
    return "";
    }

[/edit]
Then just call it:

C#

cmdTemp.Parameters.AddWithValue("@comment_NAME30", AlwaysAString(row.Cells[0]));

How to assign value empty when string is null in C#

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