Question

Let’s say I have Customers table and I want to filter it by the following:

• Country: All, US, UK, Canada
• Income: All, low, high, medium
• Age:All, teenager, adult, senior

if I had to build an SQL string for this filter, it would be something like this:

if (Country != "All") sql += "country = " + Country
if (Income != "All") sql += "and income = " + Income
if (Age != "All") sql += "and age = " + Age;

So, basically, the user can filter by some, but not necessary all fields.

How do you do this using Entity Framework ?

Thanks !

Answer 1

You can include conditional parameter this way:

return Customers.Where(
                customer =>
                customer.Name == Name &&
                (Age == "All" || customer.Age == Age) &&
                (Income == "All" || customer.Income == Income) &&
                (Country == "All" || customer.Country == Country)
                ).ToList();

If some condition is true (e.g. country is equal to All), then all parameter condition becomes true, and this parameter does not filter result.