Question

I have an Entity Framework Entity that looks something like this:

class ListItemEtlObject
{
    public int ID { get; set; }
    public string ProjectName { get; set; }
    public string ProjectType { get; set; }
    public string ProjectCode { get; set; }
    public string ProjectDescription { get; set; }
    public string JobNo { get; set; }
    public string JobDescription { get; set; }
    public bool Include { get; set; }
}

I am pulling items from two different data sources into IEnumerable lists. How might I go about comparing the items without using a bunch of if statements to check if there are differences between the properties’ values and then set the property’s value if they do not match? The idea is to keep the lists synchronized. Also list A has an ID value set, list B does not. I just feel there is a better way to do this than a bunch of

if(objectA.ProjectName != objectB.ProjectName)
{
   objectA.ProjectName = objectB.ProjectName;
}

Answer 1

If you have control of the source object then the best declarative way to support value based equality is to implement IEquatable<T>. This does unfortunately require you to enumerate out all of those checks but it’s done once at the actual object definition location and doesn’t need to be repeated throughout the code base.

class ListItemEtlObject : IEquatable<ListITemEtlObject>
{
  ...
  public void Equals(ListITemEtlObject other) {
    if (other == null) {
      return false;
    }
    return 
      ID == other.ID &&
      ProjectName == other.ProjectName &&
      ProjectType == other.ProjectType &&
      ... ;
  }
}

Additionally you could choose to overload the equality operator on the object type and allow consumers to simply use != and == on ListItemEtlObject instances and get value equality instead of reference equality.

public static bool operator==(ListItemEtlObject left, ListItemEtlObject right) {
  return EqualityComparer<ListItemEtlObject>.Default.Equals(left, right);
}
public static bool operator!=(ListItemEtlObject left, ListItemEtlObject right) {
  return !(left == right);
}