Use .NET Reflection APIs to facilitate get/set property

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Introduction

This is a utilities component for dynamic access to .NET objects' properties/fields. It offers low-level utility classes that assist in getting and setting property values on .NET classes.

In general, we design a data access tier for software system, then need dynamic get/set for the object properties. Of course, we must use .NET Reflection API, but we need a simple method.

For these purposes, I designed this utilities component.

Five formats for referencing a particular property value of an object are supported:

• Simple (name) - The specified name identifies an individual property of a particular object.
• Nested (name1.name2.name3) The first name element is used to select a property getter, as for simple references above. The object returned for this property is then consulted, using the same approach, for a property getter for a property named name2, and so on. The property value that is ultimately retrieved or modified is the one identified by the last name element.
• Indexed (name[index]) - The underlying property value is assumed to be an array, or an instance of IList. The appropriate (zero-relative) entry in the array is selected.
• Mapped (name[key]) - the name is an instance of IDictionary, key type is System.String.
• Combined (name1.name2[index].name3[key]) - Combining mapped, nested, and indexed references is also supported.

Using the code

Simple Test:

[Test]
public void TestReadProperty()
{
    EmployeeInfo emp= GetNewEmployee();

    Assert.AreEqual("ID101",DynaAccessUtils.GetProperty(emp,"Emp_id"));
    Assert.AreEqual("cao",DynaAccessUtils.GetProperty(emp,"Fname"));
    Assert.AreEqual(new DateTime(2004,12,30), 
                    DynaAccessUtils.GetProperty(emp,"Hire_date"));
    Assert.AreEqual(200,DynaAccessUtils.GetProperty(emp,"Job_id"));
    Assert.AreEqual(10,DynaAccessUtils.GetProperty(emp,"Job_lvl"));
    Assert.AreEqual("ju",DynaAccessUtils.GetProperty(emp,"Lname"));
    Assert.AreEqual("Minit",DynaAccessUtils.GetProperty(emp,"Minit"));
    Assert.AreEqual("pubid",DynaAccessUtils.GetProperty(emp,"Pub_id"));
    Assert.AreEqual(  new Guid("00000000-0000-0000-0000-000000000000"), 
                                DynaAccessUtils.GetProperty(emp,"Id"));
}

[Test]
public void TestWriteProperty()
{
    EmployeeInfo emp= GetNewEmployee();

    DynaAccessUtils.SetProperty(emp,"Emp_id","ID202");
    DynaAccessUtils.SetProperty(emp,"Hire_date",new DateTime(2005,1,1));
    DynaAccessUtils.SetProperty(emp,"Job_id",300);

    Assert.AreEqual( "ID202",emp.Emp_id );
    Assert.AreEqual(new DateTime(2005,1,1) , emp.Hire_date);
    Assert.AreEqual(  300,emp.Job_id);

}

[Test]
public void TestWriteProperty2()
{
    EmployeeInfo emp= GetNewEmployee();

    DynaAccessUtils.SetProperty(emp,"Emp_id","ID202");
    DynaAccessUtils.SetProperty(emp,"Hire_date","2005-1-1");
    DynaAccessUtils.SetProperty(emp,"Job_id","300");
    DynaAccessUtils.SetProperty(emp,"Id","382c74c3-721d-4f34-80e5-57657b6cbc27");

    Assert.AreEqual( "ID202",emp.Emp_id );
    Assert.AreEqual(new DateTime(2005,1,1) , emp.Hire_date);
    Assert.AreEqual(  300,emp.Job_id);
    Assert.AreEqual(  new Guid("382c74c3-721d-4f34-80e5-57657b6cbc27"),emp.Id);

}

List Test:

[Test]
public void TestReadProperty()
{
    ArrayList list = new ArrayList();
    list.Add(GetNewEmployee("id001"));
    list.Add(GetNewEmployee("id002"));
    list.Add(GetNewEmployee("id003"));

    Assert.AreEqual("id001",DynaAccessUtils.GetProperty(list,"[0].Emp_id"));
    Assert.AreEqual("id002",DynaAccessUtils.GetProperty(list,"[1].Emp_id"));
    Assert.AreEqual("id003",DynaAccessUtils.GetProperty(list,"[2].Emp_id"));
}

[Test]
public void TestWriteProperty()
{
    ArrayList list = new ArrayList();
    list.Add(GetNewEmployee("id001"));
    list.Add(GetNewEmployee("id002"));
    list.Add(GetNewEmployee("id003"));

    DynaAccessUtils.SetProperty(list,"[0].Emp_id","new001");
    DynaAccessUtils.SetProperty(list,"[1].Emp_id","new002");
    DynaAccessUtils.SetProperty(list,"[2].Emp_id","new003");

    Assert.AreEqual("new001",((EmployeeInfo)list[0]).Emp_id);
    Assert.AreEqual("new002",((EmployeeInfo)list[1]).Emp_id);
    Assert.AreEqual("new003",((EmployeeInfo)list[2]).Emp_id);
}

Map Test:

[Test]
public void TestReadProperty()
{
    Hashtable map = new Hashtable();
    map.Add("first",GetNewEmployee("id001"));
    map.Add("second",GetNewEmployee("id002"));
    map.Add("three",GetNewEmployee("id003"));

    Assert.AreEqual("id001",DynaAccessUtils.GetProperty(map,"first.Emp_id"));
    Assert.AreEqual("id002",DynaAccessUtils.GetProperty(map,"second.Emp_id"));
    Assert.AreEqual("id003",DynaAccessUtils.GetProperty(map,"three.Emp_id"));
}

[Test]
public void TestWriteProperty()
{
    Hashtable map = new Hashtable();
    map.Add("first",GetNewEmployee("id001"));
    map.Add("second",GetNewEmployee("id002"));
    map.Add("three",GetNewEmployee("id003"));

    DynaAccessUtils.SetProperty(map,"first.Emp_id","new001");
    DynaAccessUtils.SetProperty(map,"second.Emp_id","new002");
    DynaAccessUtils.SetProperty(map,"three.Emp_id","new003");

    Assert.AreEqual("new001",((EmployeeInfo)map["first"]).Emp_id);
    Assert.AreEqual("new002",((EmployeeInfo)map["second"]).Emp_id);
    Assert.AreEqual("new003",((EmployeeInfo)map["three"]).Emp_id);
}

History

14/1/2005 - Initial release.

Contact

Your any feedback and suggestions, please send them to HongJu.Cao (hjcao_wei@hotmail.com).