CODEWITHSUNDEEP
c#lambda
zey
zey

Reputation: 6103

quick way to update in lambda expression

Here is how I get data from database and update using lambda expression .

 item _myItem = db.myDBContext.items.Where(x => x.id == 0).SingleOrDefault();
 _myItem.field1 = "myValueForField1";
 _myItem.field2 = "myValueForField2";
 _myItem.field3 = "myValueForField3";
 _myItem.field4 = "myValueForField4";
  db.myDBContext.SubmitChanges();

It's just a sample, my table has many columns.
If I follow this way, I have to assign each column (field1,field2,..).
If I have 20 columns, I have to write 20 lines of code.
Can I assign field name dynamically ?
Like 

_myItem[dynamicFieldName] = ...;

Or is there any way to make it better ?
I just want to assign the field names dynamically.

Upvotes: 1

Views: 1465

Answers (4)

VJPPaz
VJPPaz

Reputation: 1015

Try this one:

item _myItem = db.myDBContext.items.Where(x => x.id == 0).SingleOrDefault();

var typ = typeof(item);
typ.GetProperties().ToList().Foreach(m=> m.SetValue(_myItem,"yourvalue", null));

db.myDBContext.SubmitChanges();

Upvotes: 1

Alexmelyon
Alexmelyon

Reputation: 1239

You can not use reflection.
You would make indexer in your Item class. And use extension methods to convert to specific type.

using System;
using System.Collections.Generic;
namespace ConsoleApplication1
{
    static class MyExtensions
    {
        public static int toInt32(this string field)
        {
            return Convert.ToInt32(field);
        }
    }
    class MySpecificList
    {
        Dictionary<string, string> _fields = new Dictionary<string, string>();
        public string this[string name]
        {
            get
            {
                return _fields[name];
            }
            set
            {
                _fields[name] = value;
            }
        }
        static void Main(string[] args)
        {
            MySpecificList list = new MySpecificList();
            list["field1"] = "1";
            Console.WriteLine(list["field1"].toInt32() + 1);
        }
    }
}

Upvotes: 0

Jamiec
Jamiec

Reputation: 136114

Without using reflection, you cannot assign fields dynamically in that way.

Using reflection, you can, but there is a performance hit associated.

for example:

var myField = "field1";
var field = _item.GetType().GetField(myField); // perhaps GetProperty() - depending on if its a field or a property.
field.SetValue(_item,"myValueForField1");

Obviously that can be done in a loop, with all your field names in an array or list of some sort.

Upvotes: 1

Elo
Elo

Reputation: 2352

You can use reflection:

PropertyInfo pInfo = _myItem.GetType().GetProperty("field2"):
pInfo.SetValue(_myItem, "myValueForField2");

Upvotes: 0

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