Loop through values of properties of an object?

Question

I know there are a bunch of topics with the same question, but I am just so confused.

I want to loop through my objects properties and write the value.

But everything I have seen says to

        Dim pinfo() As PropertyInfo = MyCompanies(1).GetType().GetProperties()

This creates an array with the info of the properties, but it does not store the actual value of that object.property,

The name of the property is ticker, but the value of Mycompanies(1).ticker is AMZN.

My Code:

 Dim pinfo() As PropertyInfo = MyCompanies(1).GetType().GetProperties()

 'Loop through Properties 
 For pi = 0 To pinfo.Length - 1
        'I want to get the values of each property
        Console.WriteLine(?)
    Next pi

Note: MyCompanies(1) is just the second object in an object array, all objects are of the company class

https://msdn.microsoft.com/en-us/library/b05d59ty(v=vs.110).aspx doesnt help either. It leads me to believe that I should do:

    For Each pi In pinfo
        'I want to get the values of each property
        Console.WriteLine(PropertyInfo.GetValue(MyCompanies(1))
    Next pi

but that wont even build. Is it because I am trying to give it the object by using the position in the array?

...and outside of this loop I will have to loop through my object array, so i figured i could just replace the 1 with an i...

The **[PropertyInfo Class](https://msdn.microsoft.com/en-us/library/system.reflection.propertyinfo(v=vs.110).aspx)** has many properties and methods (such as what datatype it is, is it readonly, etc). As you iterate (loop) you will need to drill into it to get whatever it is you want — Ňɏssa Pøngjǣrdenlarp, Dec 30 '17 at 02:18

score 3 · Accepted Answer · answered Dec 30 '17 at 02:30

You should be calling like this:

Dim props As PropertyInfo() = MyCompanies(1).GetType().GetProperties()

Note GetProperties returns an array of PropertyInfo - one representing each property.

Then, to loop:

For Each prop in props
    Console.WriteLine(prop.GetValue(MyCompanies(1)).ToString())
Next

Note that the PropertyInfo class does not contain a reference to the specific object from which you derived the type information (which is why you can't just call prop.GetValue()).

It is simply a kind of template which describes the type in question - and therefore you have to pass it a reference to the actual object whose property value you want to be extracted.

If you were accessing multiple MyCompanies objects, you would only derive the type information once, and you would then reuse it.

For example:

Dim props As PropertyInfo() = MyCompanies(1).GetType().GetProperties()

For Each company in MyCompanies

    Console.WriteLine(company.ToString()) 'e.g. to print the company name

    For Each prop in props
        Console.WriteLine(prop.GetValue(company).ToString())
    Next
Next

I haven't tested the code so excuse any small slips.

why do the parentheses go after propertyinfo rather than props? Every other time I've declared an array I write dim array(length) as type — ThomasRones, Dec 30 '17 at 02:42
That's just my preference in this case, because I conceive an array as being a kind of "type". If you are initialising a fixed-length array, I believe the kosher method of declaration is Dim array As Integer() = New Integer(2) {}. But there are syntax holdovers from VB6, where you had to simply say Dim array(2) As Integer - bearing in mind Basic (which predates C++) was retrofitted with object-oriented principles and it's array syntax predated that retrofitment. — Steve, Dec 30 '17 at 03:14

Loop through values of properties of an object?

1 Answers1