C# Reflection and arrays

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I have a Windows Forms TreeGrid, populated via reflection applied on some bussiness classes I wrote. Each line of the TreeGrid shows my class' properties, along with a column where I can edit the valueof the property.

My problems arise when I have "public xxx[]" on my class. I can populate the tree via code with any number of occurrences of "xxx" object, using buttons "Add" and "Delete". This thing works fine.

But the question is:

How I use reflection to populate my objects from the values of the tree when this objects are arrays, declared but not initialized im my bussiness classes?

When I finish this code, I will post it under an article here in CP.

Any hints or help?

TIA

Nilo
Brazil

UPDATE: The significant portion of my code below:

C#

        /// <summary>
        /// Gets the properties of the current object, creating a tree node for each.
        /// Splits the subtrees recursivelly when a property is found that is told to be arrays type.
        /// </summary>
        /// <param name="obj">object to be inspected</param>
        /// <param name="origin">tree where add the nodes obtained from the object</param>
        private void getProperties(Object obj, ref TreeGridNode origin)
        {
            int qtyItems = 0;
            string value = "";
            PropertyInfo[] propertyInfos;
            TreeGridNode node;
            bool dynamic = false;

            // Gets all the properties of the object
            propertyInfos = obj.GetType().GetProperties();

            // process all the properties from the object, using them to populate the tree 
            foreach (PropertyInfo p in propertyInfos)
            {
                // Properties that originally can't be written are hidden here from the user...
                // It makes no sense alter properties that are read-only... 
                if (!p.CanWrite)
                    continue;

                // The property DeviceID is not used when configuring Lists
                // So, let's hide it from the tree.
                if (p.Name.Equals("DeviceID"))
                    continue;

                // Gets advanced information from the property's dictionary
                //TypeInfo tinfo = dic.getTypeName(p.PropertyType.ToString());

                qtyItems = 1;
                dynamic = false;

                // Add a row for each property, setting your name, type and value
                if (!p.PropertyType.IsArray || p.PropertyType.ToString().Equals("System.Byte[]"))
                {
                    if (p.GetValue(obj, null) != null)
                        value = p.GetValue(obj, null).ToString();
                }
                else
                {
                    if (p.GetValue(obj, null) != null)
                    {
                        Array arr = p.GetValue(obj, null) as Array;
                        qtyItems = arr.Length;
                    }
                    else
                    {
                        qtyItems = 0;
                        dynamic = true;
//-----------------------------------------------------------------------
//  Here I wish to create the dynamic array defined in my original object
//  as 
//
//       "public xxxx[]"
//  
//  Note that I can insert recursively the properties of class "xxxx"
//  when I click on an "Add" button.
//
//  My trouble is set the values I furnish via grid edition on the the
//  object I created.
//
//  When the property is not an "public xxxx[]", my code works like a charm.
//  
//-----------------------------------------------------------------------
                    }
                }

                node = origin.Nodes.Add(p.Name, (dynamic?"":p.PropertyType.ToString()), (qtyItems == 1 ? value : ""), (qtyItems == 1 ? true : false), qtyItems, p, obj, dynamic,false);

                // If the property should have a subtree, recurse starting at it, generating the subtree
                if (qtyItems > 1)
                {
                    for (int i = 1; i <= qtyItems; i++)
                    {
                        // Sets current node color to red
                        node.DefaultCellStyle.ForeColor = Color.Red;

                        // Gets the complete array
                        Array ar = (Array)p.GetValue(obj, null);

                        // Add the node to the newly created subtree
                        TreeGridNode subRoot = node.Nodes.Add(p.Name + " " + i, "", "", false, 1, p.GetValue(obj, null), ar, ar, false,false);

                        // Proceed recursively, startting for the (i)th occurrence of it... 
                        this.getProperties(ar.GetValue(i - 1), ref subRoot);
                    }
                }
            }
        }

Posted 8-May-12 7:09am

NiloPaim

Updated 8-May-12 7:27am

v2

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Comments

Ganesan Senthilvel 8-May-12 13:14pm

Share your code for clarity

Mehdi Gholam 8-May-12 13:14pm

Are you trying to set values in your entity or get the values?

NiloPaim 8-May-12 14:25pm

Set values, Mehdi.

wizardzz 8-May-12 13:23pm

Reason for my vote of 5
5 for offering to post tip or article. Thank you.

NiloPaim 8-May-12 13:25pm

Question improved with my code.

@wizardzz, thanks for your vote. I'll post the solution when i have it.

Sergey Alexandrovich Kryukov 8-May-12 13:47pm

How are you going to write an article if you have problem mastering this simple techniques?
Also, there are two ways: just Reflection and Reflection.Emit. Reflection is too slow.
--SA

NiloPaim 8-May-12 13:59pm

Good point, man.

I'm sure that I can learn something new to me with the help of experient professionals here.

I couldn't see this as "simple techniques", but obviously I haven't enough knowledge as you.

My intention is to create a component that can be used to set the properties of any class' object. I'm almost there, I know, and I think that such component would be useful for others. That's the reason to write an article describing the component, when completed.

By the way, I use this as initial inspiration:
http://www.codeproject.com/Questions/41692/to-write-or-not-to-write-an-article

Thanks for your interest.

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This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Sergey Alexandrovich Kryukov · Accepted Answer · 2012-05-08T09:11:00

The most basic steps are:

C#

using System;
using System.Reflection;

//...

class Sample {
    int[] array; // intentionally left private, to demonstrate the effect of Reflection
} //class Sample

//...

Sample sample = new Sample(); // could do it using Reflection, via invocation of a constructor
// but let's focus on the array:
BindingFlags universalBindingFlags = BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.Static;
Type type = typeof(Sample);
FieldInfo arrayField = type.GetFields(universalBindingFlags)[0]; // just in this case
arrayField.SetValue(sample, new int[] { 1, 2, 3 } /* or something from your tree :-) */ );

This is how to do it with Reflection. Again, it's pretty slow. You can also emit the code in the form of either emitted assembly or in some DynamicMethod. It makes enormous gain in performance (orders of magnitude), if you do reflection part only once and reuse the call to the method(s) many times.

—SA

C# Reflection and arrays

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C# Reflection and arrays

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