Is it possible to make LINQ where filter conditional?-CodePudding

I have this code, I want to change Where from

Where(p => p.FirstName.StartsWith(v))

Where(p => (p.FirstName p.LastName).Contains(v) if v.length > 1

[HttpGet("search")]
public IActionResult SearchPerson([FromQuery] string v="A", [FromQuery] int page=1)
{
    var personList = _ctx.People.Where(p => p.FirstName.StartsWith(v))
                                .Skip((page - 1) * 30)
                                .Take(30);    
    return Ok(personList);
}

Is it possible ?

CodePudding user response：

You could add the Where clause, or any number of Where clauses, like this. It is not clear what you want to do if v length is not greater than 1, but I hope you get the idea:

IEnumerable<Person> personList = ctx.People;

if(v.length > 1) 
{
   personList = personList.Where(p => (p.FirstName   p.LastName).Contains(v));
}
else
{
   //a different Where clause?
}

return Ok(personList.Skip((page - 1) * 30).Take(30));

CodePudding user response：

You need something like this:

_ctx.People.Where(p =>
{
    if (v.Length > 1)
    {
        return (p.FirstName   p.LastName).Contains(v);
    }

    return true;
})

but you can also combine them with && just like @Qwerty said :)

CodePudding user response：

You can use && within Where clause to combine two conditions

Sample :

        List<Person> people = new List<Person>();
        people.Add(new Person() { FirstName = "1", LastName = "8" });
        people.Add(new Person() { FirstName = "1", LastName = "8" });
        people.Add(new Person() { FirstName = "1", LastName = "8" });
        people.Add(new Person() { FirstName = "1", LastName = "8" });
        people.Add(new Person() { FirstName = "1", LastName = "8" });
        people.Add(new Person() { FirstName = "2", LastName = "8" });

        var test = "1";

        var list1 = people.Where(p => test.Length > 0 && (p.FirstName  p.LastName).StartsWith(test)).ToList();