LINQ query not working with Select2

Question

I'm using the Select2 plugin for searching on my table through LINQ. The issue I'm facing is the multi-select returns me an array and I get an error that I cant convert string[] to string. Here is my view:

<select class="js-example-basic-multiple"name="country[]" multiple="multiple">
  <option value="">Select a country...</option>
  <option value="AF">Afghanistan</option>
  <option value="AX">Åland Islands</option>
  <option value="AL">Albania</option>
</select>

I want on the controller to search records that I select from the dropdown. My controller is:

var model = from r in db.Clients
  orderby r.DateRegister descending
  where (r.DateRegister >= datepicker3 && r.DateRegister <= datepicker2 || datepicker2 == null || datepicker3 == null)
  where r.Name.Contains(FirstName) || FirstName == "" || FirstName == null
  where r.LastName.Contains(LastName) || LastName == "" || LastName == null
  where r.Phone.Contains(Phone) || Phone == "" || Phone == null
  where r.Email.Contains(Email) || Email == "" || Email == null
  where r.PromoCode.Contains(PromoCode) || PromoCode == "" || PromoCode == null
  where r.Brand.Contains(Brand) || Brand == "" || Brand == null
  where r.Rentetiion == Retetion || Retetion == null
  where r.SaleStatus == statos || statos == null
  where r.Desk == desk || desk == null
  where r.workerId == Broker || Broker == null
  where r.Country.Contains(country)||country == null

Where country will be more then 1 item to search.

Try this Eni, https://stackoverflow.com/questions/194930/how-do-i-use-linq-containsstring-instead-of-containsstring — johnny, Aug 28 '18 at 12:55
so yuor `r.Country` have only one country save in your table right? — er-sho, Aug 28 '18 at 13:00
@EniSpetsi, try this `where country.Any(c => c.Trim().ToLower().Contains(r.CountryName.Trim().ToLower()))` — er-sho, Aug 28 '18 at 14:03

er-sho · Accepted Answer · 2018-08-29T06:08:00.893

1

1) Suppose this is your Country model.

class Country
{
    public string Name { get; set; }
    public string Code { get; set; }
}

2) And this string[] contains country from your select2.

string[] country = new string[2] { "India", "Shrilanka" };

3) And those are the countries that are already in my database.

List<Country> countries = new List<Country>();
countries.Add(new Country { Name = "India", Code = "IN" });
countries.Add(new Country { Name = "Australia", Code = "AU" });
countries.Add(new Country { Name = "Shrilanka", Code = "SL" });

4) Then I used below query to filtered out countries from my database with above string[] that contains only 2 countries.

var query = (from r in countries
        where country == null || country.Any(c => c.Trim().ToLower().Contains(r.Name.Trim().ToLower()))
        select new
        {
           CountryName = r.Name,
           CountryCode = r.Code
        });


var result = query.ToList();

Trim() => Removes all leading and trailing white-space characters from the current System.String.

ToLower() => Returns a copy of this string converted to lowercase.

Output:

Try once may it help you.

edited Aug 29 '18 at 06:08

answered Aug 28 '18 at 14:19

er-sho

9,581
2
13
26

Unable to create a null constant value of type 'System.String[]'. Only entity types, enumeration types or primitive types are supported in this context i get this erro now. – Eni Spetsi Aug 28 '18 at 14:26
set your `country[]` from select2 list is in `string[]` so this error will be gone – er-sho Aug 28 '18 at 14:30
i got it like that. – Eni Spetsi Aug 28 '18 at 14:33
@Eni Spetsi, View the updated answer carefully might be it help you :) – er-sho Aug 29 '18 at 06:07
@EniSpetsi, add this condition in your where `country == null` that i added in my answer. – er-sho Sep 03 '18 at 11:19

score 0 · Answer 2 · answered Aug 28 '18 at 13:27

0

Try this,

where r.Country.Contains(c => Country.Contains(c.country) || c.country == null)

answered Aug 28 '18 at 13:27

johnny

19,272
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i get this error: Severity Code Description Project File Line Suppression State Error CS1660 Cannot convert lambda expression to type 'string' because it is – Eni Spetsi Aug 28 '18 at 13:40
1

@Eni, try to import namespace `using System.Linq;` and `using System.Data.Entity;` – er-sho Aug 28 '18 at 13:47
same error: S1660 Cannot convert lambda expression to type 'string' because it is not a delegate type – Eni Spetsi Aug 28 '18 at 13:53
@EniSpetsi please make sure on ershoaib's comment. It typically can be the fix. Example, https://stackoverflow.com/questions/19197481/cannot-convert-lambda-expression-to-type-string-because-it-is-not-a-delegate-t – johnny Aug 28 '18 at 13:56

LINQ query not working with Select2

2 Answers2