Accessing members of an object in array

Question

My question is related to arrays in c#, or what I think is an array. I have a good knowledge in the basics of c# but not much after that.

I have been tasked to make changes to a piece of code below. The code retrieves a list of records from a web service and stores them in what I might be wrongly thinking is an array. Im not sure if arrays can have keys or "columns" like below (PurchaseDate, Location etc..). If not an array what is it?

OO_WebService.Sale[] saleList= OO_webService_connection.GetSales().Sales;

Console.Writeline(saleList[0].PurchaseDate);
Console.Writeline(saleList[0].Location);

Console.Writeline(saleList[1].PurchaseDate);
Console.Writeline(saleList[1].Location);

I also need to print out all keys or column names. For example there are another 20 keys along with PurchaseDate and Location. I want to be able to print out all key names(PurchaseDate) along with their values(01/04/2014 etc..) using a for loop, for example. I know it is possible in javascript. I have tried a few times but had no luck implementing it. Any suggestions greatly appreciated.

Answer 1

You need to use reflection...

var props = saleList.GetType().GetElementType().GetProperties();

foreach (var sale in saleList)
{
    foreach (var p in props)
    {
        Console.WriteLine(p.Name + "=" + p.GetValue(sale,null));
    }
    Console.WriteLine();
}

Answer 2

The array in this case contains Sale elements. An array in C# is just a fixed-size collection of elements, and can contain either primitive types (such as int[] which you may be familiar with) or objects which is the case you're dealing with.

Instead of referring to saleList[0].PurchaseDate , you could rewrite that code as:

for (int i = 0; i < saleList.Lenght; i++)
{
    OO_WebService.Sale sale = saleList[i];
    Console.WriteLine(sale.PurchaseDate);
    Console.WriteLine(sale.Location);
}

So each element, accessed by saleList[ index ] is an instance of the Sale class. I hope that clears things up for you.

Answer 3

You could use right-click on Sale and in the menu select 'Go To Definition'. That will give you all the properties. If Sale is dynamic (eg, can have more or less properties at a later time), you can use reflection (as Tim said). This can be done as follows:

Type type = typeof(Sale);
PropertyInfo[] info = type.GetProperties(BindingFlags.Instance | BindingFlags.Public | BindingFlags.DeclaredOnly);
foreach (var i in info)
{
    Debug.WriteLine(i.Name + " = " + i.GetValue(this, null));
}

Note that the return value of GetValue is object and maybe needs to be casted to the correct type. Debug.WriteLine will call the objects default ToString() implementation.