query multiple conditions using Entity Framework

Question

How do I query multiple conditions, and when one of the conditions is empty is ignored, and the other conditions apply ?

this Is My Code

            var SalesAsInt = Convert.ToInt32(txtSalesNo.Text);
            var YearAsInt = Convert.ToInt32(cbxYear.Text);
            var MonthAsInt = Convert.ToInt32(cbxMonth.Text);
            var DayaAsInt = Convert.ToInt32(cbxDay.Text);
            using (var dbcontext = new Database.SalesEntities())
            {
                BindingSource VSalesIncome = new BindingSource();
                VSalesIncome.DataSource = dbcontext
                                 .VSalesIncomes
                                 .Where(u => u.SalesCode  == SalesAsInt )
                                 .Where(u => u.YearIncome == YearAsInt)
                                 .Where(u => u.MonthIncome == MonthAsInt)
                                 .Where(u => u.DayIncome == DayaAsInt)
                                 .ToList();

                dgvadministration.DataSource = VSalesIncome;
            }

Error When any text box is Empty

System.FormatException: 'Input string was not in a correct format.'

jdweng · Accepted Answer · 2019-11-07 17:19:57Z

2

Try following two changes :

int? SalesAsInt = (txtSalesNo.Text == string.Empty) ? null : (int?)Convert.ToInt32(txtSalesNo.Text);

.Where(u => (SalesAsInt == null) ? true : u.SalesCode  == SalesAsInt )

edited Nov 7, 2019 at 17:19

answered Nov 7, 2019 at 16:57

jdweng

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3 Comments

Jakub Rusilko Over a year ago

To expand on this answer. The first change covers the case of the Exception when you cannot convert from a value that is invalid. Second change is a simple boolean logic - each "Where" condition is checked against an item in your database and the item is returned if the Where returns true, so you want this to happen if the given filter matches or if the filter is empty.

Ahmed Abdo Over a year ago

this line int? SalesAsInt = (txtSalesNo.Text == string.Empty) ? null :Convert.ToInt32(txtSalesNo.Text); Error Severity Code Description Project File Line Suppression State Error CS0173 Type of conditional expression cannot be determined because there is no implicit conversion between '<null>' and 'int' Sales Saya World C:\Users\20101\Desktop\Sales Saya World\Sales Saya World\Report\frmSalesIncome.cs 39 Active

jdweng Over a year ago

Convert.Toint32 returns a int so you need a cast : (int?)Convert.ToInt32(txtSalesNo.Text)

ESG · Accepted Answer · 2019-11-07 16:54:28Z

0

You can wrap your Where methods in if statements

var query = VSalesIncome.DataSource = dbcontext.VSalesIncomes
if (SalesAsInt > 0)
    query = query.Where(u => u.SalesCode  == SalesAsInt)
// repeat as needed
VSalesIncome.DataSource = query.ToList()

answered Nov 7, 2019 at 16:54

ESG

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