How to write a generic LINQ query for filtering of data based on first name middle name and last name - entity-framework

Question

I have one table which contains employees records like first , middle, last name. I have 3 textboxes for entering all these.
Now on .net side I want to write a single LINQ query to filter data based on first name middle name and last name. Any of these 3 fields can be blank.
Is these any way to write a single generic LINQ query?

Answer 1

public IList<Employee> GetEmployees(string first, string middle, string last)
{
var query = context.Employees.AsQueryable();
if (!string.IsNullOrWhiteSpace(first))
{
query = query.Where(x => x.FirstName == first);
}
if (!string.IsNullOrWhiteSpace(middle))
{
query = query.Where(x => x.MiddleName == middle);
}
if (!string.IsNullOrWhiteSpace(last))
{
query = query.Where(x => x.LastName == last);
}
return query.Select(x =>
new Employee
{
FullName = string.Join(" ", new string[] { x.FirstName, x.MiddleName, x.LastName}.Where(y => !string.IsNullOrWhiteSpace(y)))
})
.ToList();
}

Answer 2

You can write one linq query with or condition like bellow
_context.tablename.where(p=>p.firstName.contains(txtFirstName) || p.middleName.contains(txtMiddleName) || p.lastName.contains(txtLastName)).ToList();
Change tablename with you database table in above linq query

Answer 3

when iterating just verify if the criteria in use has value
var criteria = new
{
FirstName = default(string),
MiddleName = default(string),
LastName = "Doe",
};
var query = from record in Context()
where !string.IsNullOrEmpty(criteria.FirstName)
&& record.FirstName == criteria.FirstName
|| !string.IsNullOrEmpty(criteria.MiddleName)
&& record.MiddleName == criteria.MiddleName
|| !string.IsNullOrEmpty(criteria.LastName)
&& record.LastName == criteria.LastName
select record;

Answer 4

Try something like that;
public List<Employee> RetrieveEmployees(string firstName, string lastName, string middleName)
{
var query = from employees in context.Employees
where (string.IsNullOrEmpty(firstName) || employees.FirstName == firstName) &&
(string.IsNullOrEmpty(lastName) || employees.LastName == lastName) &&
(string.IsNullOrEmpty(middleName) || employees.MiddleName == middleName)
select employees;
return query.ToList();
}