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La requête Linq renvoie true ou false

J'ai une requête où il devrait renvoyer VRAI ou FAUX. 

var query = from c in db.Emp
            from d in db.EmpDetails 
            where c.ID == d.ID && c.FirstName == "A" && c.LastName == "D" 
          // It should return TRUE when this above statement matches all these conditions

et je veux attacher le résultat de cette requête à une propriété (de type de données chaîne)

this.result = Conert.ToBoolean(query);

comment y parvenir dans LINQ? 

MODIFIER:

Classe EmpMapper

  public class EmpMapper
  {
    EmpEntities db;
    // ID column already exists in the DB
    private int ID;
    // I am creating this property to add it from the UI side, depending on the certain conditions in the query. That is why I created a separate class to map the existing ID from the DB
    bool result;
    public EmpMapper(int ID, bool result)
    {
      this.db = new EmpEntites();
      this.ID = ID;
      var query = from c in db.Emp
            from d in db.EmpDetails 
            where c.ID == d.ID && c.FirstName == "A" && c.LastName == "D" 
          // It should return TRUE when this above statement matches all these conditions
      this.result = Convert.ToBoolean(query);
    }
   public int ID
   {
    get{return this.ID;}
    set{this.ID = value;}
   }
   public bool result
   {
    get{return this.result;}
    set{this.result = value;}
   }
   }

Classe MainViewModel 

      List<EmpMapper> empMapCol = new List<EmpMapper>();

     private void Page_Loaded(object sender, RoutedEventArgs e)
    {
      var emp_query = from c in db.Emp
                      orderby c.ID
                      select a;
     List<Emp> empCol = emp_query.ToList();
     foreach(Emp item in empCol)
     {
       this.empMapCol.Add(new EmpMapper(item.ID, item.result)); 
     }
     datagrid1.ItemsSource = empMapCol;
     }
     }
c#linqlinq-to-sql
12
user1221765

essaye ça,

 var query = (from c in db.Emp
        from d in db.EmpDetails 
        where c.ID == d.ID && c.FirstName == "A" && c.LastName == "D"
         select c 
         ).Any(); 

  this.result = query; //no need to convert to boolean its already bool value
24
Satpal

Si je vous ai bien compris, vous voulez obtenir true si l’un des résultats de la requête correspond à toutes les conditions. Dans ce cas, essayez quelque chose comme ceci:

var found =
    (from c in db.Emp
    from d in db.EmpDetails
    where c.ID == y.ID && c.FirstName == "A" && c.LastName == "D"
    select c).Any();

this.result = found.ToString();
4
Maciej

Vous pouvez utiliser .Any () ou .Count (). Any () fonctionne mieux. (Cochez cette question SO pour voir pourquoi) 

.Tout()

var query = from c in db.Emp
            from d in db.EmpDetails 
            where c.ID == d.ID && c.FirstName == "A" && c.LastName == "D" 
          // It should return TRUE when this above statement matches all these conditions
this.result = query.Any().ToString()

.Compter()

var query = from c in db.Emp
            from d in db.EmpDetails 
            where c.ID == d.ID && c.FirstName == "A" && c.LastName == "D" 
          // It should return TRUE when this above statement matches all these conditions
this.result = (query.Count() > 0).ToString()
3
Oscar Foley
var query = from c in db.Emp
            from d in db.EmpDetails 
            select new { c.ID == y.ID &&  
                         c.FirstName == "A" && 
                         c.LastName == "D" };
0
Skinny Pipes

Si vous voulez vraiment avoir une réponse "true" ou "false":

    public string result
    {
        get
        {
            return db.Emp.SelectMany(c => db.EmpDetails, (c, d) => new {c, d})
                         .Where(@t => c.ID == y.ID && c.FirstName == "A" && c.LastName == "D")
                         .Select(@t => c)).Any().ToString();
        }
    }

Mais je suggérerais de transformer la propriété "résultat" en un booléen et d'enlever ToString (). Une fois que vous avez un bool, vous pouvez toujours faire un ToString () dessus

0
user2141886