Passing string[]parameter to OnGet in Razor Pages

Ok, I got it working with

var newlist = new List();
foreach (var item in ecs)
{
    var results = await (from a in _context.EvarisCaracterSpecials.Where(s => s.OrgID == orgid && s.ECS == item)
                          join b in _context.EvarisMains on a.ECS equals b.ECS into Temp1
                          from c in Temp1
                          join d in _context.EvarisMasuras on c.EMID equals d.EMID into Temp2
                          from e in Temp2
                          select new EvarisMasuraList
                          {
                              ID = a.ECS,
                              Pericol = c.Pericol,
                              FormaManifestare = c.FormaManifestare,
                              RiscInitial = c.Risc,
                              Clasa = e.Clasa,
                              Masura = e.Masura,
                              RiscFinal = e.RiscFinal
                          }).ToListAsync();


    newlist.AddRange(results);
}

EvarisListCS = newlist;

if (EvarisListCS.Count > 0)
{
    HaveListCS = true;
}

I end up creating a table to store data from query that runs those parameters and display then on main page. The data I will clean with just a click. There might be problems that doesn't have a quick resolve :(

Let me add a clarification. EvarisListCS model is just a View, it does not add data it just display data. foreach loop has to get lines of data for each ecs string. This I don't know how to do

Following error, but this method makes sense to me

 'IList' does not contain a definition for 'AddRange' and no accessible extension method 'AddRange' accepting a first argument of type 'IList' could be found (are you missing a using directive or an assembly reference?)  

public IList EvarisListCS { get; set; }

using System;
using System.Collections.Generic;
using System.Linq;
using System.Security.Claims;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.RazorPages;
using Microsoft.AspNetCore.Mvc.Rendering;
using Microsoft.EntityFrameworkCore;
using RoSafety.Data;
using RoSafety.Models;
using RoSafety.Models.RA;

Edit no.2. Is it worth to mention that EvarisListCS is not saved just displayed/

use 

EvarisListCS.AddRange(res);

For the second solution I have an error for

EvarisListCS.Add(res); 

cannot convert from 'System.Collections.Generic.List' to 'RoSafety.Models.RA.EvarisMasuraListCS'  
 

Same error, yes

btw parameters are sent like this

https://localhost:xxxxxx/ro/pages/evaris?ecs=9a01a8b3-6d8b-4ab6-a078-42b2fff39c06&ecs=9efe95dd-0411-4d2a-8884-ad4dffe18306

otherwise you can add results to list

foreach(var dataGet in ecs)
{
    var res= await (from a in _context.EvarisCaracterSpecials.Where(s => s.OrgID == orgid && s.ECS == dataGet)
                          join b in _context.EvarisMains on a.ECS equals b.ECS into Temp1
                          from c in Temp1
                          join d in _context.EvarisMasuras on c.EMID equals d.EMID into Temp2
                          from e in Temp2
                          select new EvarisMasuraListCS
                          {
                              ECS = a.ECS,
                              OrgID = a.OrgID,
                              CaracterSpecial = a.Denumire,
                              Pericol = c.Categorie,
                              FormaManifestare = c.FormaManifestare,
                              RiscInitial = c.Risc,
                              Clasa = e.Clasa,
                              Masura = e.Masura,
                              RiscFinal = e.RiscFinal
                          }).ToListAsync();
    EvarisListCS.Add(res);
    if(EvarisListCS.Count > 0)
    {
        HaveListCS = true;
    }
}

what happens when you do just this, does it throw error

string[] ecs= {"ECS1","ECS2"};
var res= await_context.EvarisCaracterSpecials.Where(s => s.OrgID == orgid && ecs.Contains(s => s.ECS));

Thank you Sachin, I receive following error

CS1660: Cannot convert lambda expresssion to type 'type' because it is not a delegate type

if(ecs != null)
{
    EvarisListCS = await (from a in _context.EvarisCaracterSpecials.Where(s => s.OrgID == orgid && ecs.Contains(s => s.ECS))
                              join b in _context.EvarisMains on a.ECS equals b.ECS into Temp1
                              from c in Temp1
                              join d in _context.EvarisMasuras on c.EMID equals d.EMID into Temp2
                              from e in Temp2
                              select new EvarisMasuraListCS
                              {
                                  ECS = a.ECS,
                                  OrgID = a.OrgID,
                                  CaracterSpecial = a.Denumire,
                                  Pericol = c.Categorie,
                                  FormaManifestare = c.FormaManifestare,
                                  RiscInitial = c.Risc,
                                  Clasa = e.Clasa,
                                  Masura = e.Masura,
                                  RiscFinal = e.RiscFinal
                              }).ToListAsync();
        if(EvarisListCS.Count > 0)
        {
            HaveListCS = true;
        }
}

do this instead

EvarisListCS = await (from a in _context.EvarisCaracterSpecials.Where(s => s.OrgID == orgid && ecs.conatins(x=>x.ECS)
                                          join b in _context.EvarisMains on a.ECS equals b.ECS into Temp1
                                          from c in Temp1
                                          join d in _context.EvarisMasuras on c.EMID equals d.EMID into Temp2
                                          from e in Temp2
                                          select new EvarisMasuraListCS
                                          {
                                              ECS = a.ECS,
                                              OrgID = a.OrgID,
                                              CaracterSpecial = a.Denumire,
                                              Pericol = c.Categorie,
                                              FormaManifestare = c.FormaManifestare,
                                              RiscInitial = c.Risc,
                                              Clasa = e.Clasa,
                                              Masura = e.Masura,
                                              RiscFinal = e.RiscFinal
                                          }).ToListAsync();