Entity Framework - How to update fields from a list of key-value pairs?

问题

Let's say the user modifies his profile record that contains fields such as FirstName, LastName, Email, etc.

For each field that is modified, the change is stored as a key-value pair in a list of type:

List<Tuple<string, object>>

The key in this key-value pair represents the actual table column.

While trying to update the record, here is one way to do it:

foreach (Tuple<string, object> field in changeList) {
    if (field.Item1.equals("FirstName")) {
        user.FirstName = field.Item2;
    }
    if (field.Item1.equals("Email")) {
       user.Email = field.Item2;
    }
    ...
}

db.SaveChanges()

I am thinking there must be a better way to accomplish this.

I guess I could use reflection to set each property on the user

foreach(tuple<string, object> field in changeList) {
  user.GetType().InvokeMember(field.Item1,
     BindingFlags.Instance | BindingFlags.Public | BindingFlags.SetProperty,
     Type.DefaultBinder, user, field.Item2);    
}

I am wondering if there is even better way. Perhaps I could build a "var" object dynamically that will also let me use TryUpdateModel() method.

回答1:

I have done something similar but using a custom object of type string and object. I also don't know if this is the efficient one but it gets the job done. To demonstrate I have used Tuple where first item1 is string and item2 is an object.

List<Tuple<string, object>> listTuple = new List<Tuple<string, object>>();

listTuple.Add(new Tuple<string, object>("FirstName", "Foo"));
listTuple.Add(new Tuple<string, object>("LastName", "Bar"));


PropertyInfo[] props = user.GetType().GetProperties();
    foreach (var prop in props)
    {
      if (prop.PropertyType.Name == "ICollection`1")
      {
        //Do not do anything these are navigation properties in entity framework.
        //For eg. If User has Applications then do not set values for Applications.
      }
      else
        {
                //Match each property with matching Item1 in Tuple.
            var myTuple = listTuple.Where(x => x.Item1 == prop.Name).First();
            //Set Users Property using myTuple's Item2 which is an object here. 
            prop.SetValue(user, myTuple.Item2, null);
        }
    }

回答2:

One way is to use the old pal ADO.NET.

The other way is Dynamic LINQ

Edit

Sorry, I Think Dynamic LINQ can only be used for filtering. May be ADO.NET is the best option. I'm out of ideas.

来源：https://stackoverflow.com/questions/19349285/entity-framework-how-to-update-fields-from-a-list-of-key-value-pairs

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