Can't convert from int to "classname"

Question

While building a ASP.NET-MVC website I was trying to implement a EDIT page on my website, but I'm having some difficulties, particulary in my Controller. The error is in this class, pointing to the ID:

Answer 1

Issue & Concern

According to List<T>.Contains(T), you need parse T object which is GestaoAlertas object to your addresses (List<GestaoAlertas> type).

Hence, you get the error below as it is an unmatched type with int

It is not possible to convert from int to "hdsportal.GestaoAlertas"

for this line:

GestaoAlertas _teste = addresses.Contains(ID);

And List<T>.Contains(T) returns the boolean result.

public bool Contains (T item);

Determines whether an element is in the List.

---

Solution(s)

Assumptions:

1. addresses contain GestaoAlertas records

You can get GestaoAlertas element from addresses by ID with either of these LINQ methods:

Pre-requisite:

Import System.Linq namespace.

using System.Linq;

Solution 1: Enumerable.SingleOrDefault

Returns a single, specific element of a sequence, or a default value if that element is not found.

Note: It will throw InvalidOperationException if input sequence contains more than one element. Good to be use for unique identifier such as ID.

GestaoAlertas _teste = addresses.SingleOrDefault(x => x.ID == ID);

---

Solution 2: Enumerable.Single

Returns a single, specific element of a sequence.

Note: It will throw ArgumentNullException if it returns null.

GestaoAlertas _teste = addresses.Single(x => x.ID == ID);

---

Solution 3: Enumerable.FirstOrDefault

Returns the first element of a sequence, or a default value if no element is found.

GestaoAlertas _teste = addresses.FirstOrDefault(x => x.ID == ID);

---

Solution 4: Enumerable.First

Returns the first element of a sequence.

Note: It will throw ArgumentNullException if it returns null.

GestaoAlertas _teste = addresses.First(x => x.ID == ID);