Loop through LINQ field values

Question

I have a text file with placeholders such as:

Thank you for your order [OrderNo]. Your order will be shipped to: [Name] [Street1] [Street2] etc

The placeholders are the field names in the database surrounded by brackets.

I want to retrieve a single record from the database like:

var order = (from o in testContext.OrderTables where o.OrderID == id select o).Single();

Then I'd like to be able to loop through the order object and get the field name, and it's value to fill in the placeholder.

Is this possible?

Answer 1

You might be able to do it with .GetType() and then use reflection to get at the individual properties and their values.

Answer 2

You can't use LINQ directly to iterate through the properties of an object since there isn't an enumeration of the properties of the object available on the object. You can, however, use Reflection to get at the properties of an object. LINQ may come in handy when looking through these to find the appropriate object for your placeholder.

 public Dictionary<string,object>
     ValuesForPlaceHolders( object obj,
                            IEnumerable<string> placeHolders )
 {
     var map = new Dictionary<string,object>();
     if (obj != null)
     {

         var properties = obj.GetType().GetProperties();
         foreach (string placeHolder in placeHolders)
         {
             var property = properties.Where( p => p.Name == placeHolder )
                                      .SingleOrDefault();
             if (property != null)
             {
                 map.Add( placeHolder, property.GetValue( obj, null ) );
             }
         }
     }
     return map;
 }

EDIT: The above sample was written to illustrate how LINQ could be used. My preference actually is using a helper method to get values by name. Note that the method below assumes that the property exists, but could easily be modified to return null when the property doesn't exist. In my usage my calls to it are verified by unit tests so I don't bother with the extra check.

public static class TypeHelper
{
    public static object GetPropertyValue( object obj, string name )
    {
        return obj == null ? null : obj.GetType()
                                       .GetProperty( name )
                                       .GetValue( obj, null );
    }
}

Answer 3

How about this:

void Main()
{
   var text = "Thank you for your order [OrderNo]. Your order will be shipped to: [Name] [Street1] [Street2]";

   var order = new Order() {OrderNo = 1, Name="NameA", Street1 = "Address1A", Street2="Addres2A"};

   var splitted = text.Split(']').ToList();

   var orderType = (new Order()).GetType();

   var newText = text;
   splitted.ForEach(p => 
    { 
       string field = p.Substring(p.IndexOf('[') + 1);
       if (!string.IsNullOrEmpty(field))
       {
           var result = orderType.GetProperty(field).GetValue(order, null);
           //var method = orderType.GetMethod("get_"+field);
           //var result = method.Invoke(o, null);
           newText = newText.Replace("[" + field + "]", result.ToString());
       }
    });
   Console.WriteLine(newText);
}


public class Order
{
    public Order()
    {}

    public int OrderNo {get; set;}
    public string Name {get; set;}
    public string Street1 {get; set;}
    public string Street2 {get; set;}
}

I'm not sure if I like it, but it does work. :-)