Using reflection to get instance name

[=?Utf-8?B?SmFzb24gUmV5bm9sZHM=?=]

(using .net 2.0)

Say you have a class structure like this:

class Address
....
end class

class Person
FirstName
LastName
MailingAddress as Address
BillingAddress as Address
end class

I'm using reflection to pull out the values at runtime, but I'm having
trouble when I dive into an address. When I'm traversing the object I know
when the type is address and I can get and set values on that instance, but I
can't figure a way to know if I'm looking at the mailing address or the
billing address. Is there a way to get the instance name of an object at
runtime? I've thought about setting a name property in the object, but
that's a bit of a hack and makes things much less reusable. Thanks in
advance.

[=?Utf-8?B?dGJhaW4=?=]

Not sure how you are getting the properties and types but assuming you are
using GetProperties to get an array of "PropertyInfo" objects you could use
the PropertyInfo property "Name". I do not recommend this though as you would
be hard coding property names to compare to. I would add a custom attribute
to the property that has a Name property itself (or some other marker you can
use to distinguish between which Address. Then when you get a property of
type Address to a GetCustomAttributes and iterate over these looking for the
one you added. This should make the code more readable and supportable too.
Hope this helps.
--
Thom
"Jason Reynolds" wrote:

(using .net 2.0)

Say you have a class structure like this:

class Address
...
end class

class Person
FirstName
LastName
MailingAddress as Address
BillingAddress as Address
end class

I'm using reflection to pull out the values at runtime, but I'm having
trouble when I dive into an address. When I'm traversing the object I know
when the type is address and I can get and set values on that instance, but I
can't figure a way to know if I'm looking at the mailing address or the
billing address. Is there a way to get the instance name of an object at
runtime? I've thought about setting a name property in the object, but
that's a bit of a hack and makes things much less reusable. Thanks in
advance.

[=?Utf-8?B?SmFzb24gUmV5bm9sZHM=?=]

Thanks for the response. I like the attribute idea. I was thinking along
the lines of having a name property in the address class, but didn't like the
idea at all. If I understand you correctly, you are suggesting putting
attributes on the MailingAddress and BillingAddress properties in the Person
class. I like this approach much better, but it's still not as clean as I'm
hoping for.

Going back to the PropertyInfo technique, when I loop through the
PropertyInfo array and access name I get something like
"CSQ.BusinessObjects.Address" (this is my namespace) which is the type not
the instance name. What I'm looking for is "Person.MailingAddress".

"tbain" wrote:

Not sure how you are getting the properties and types but assuming you are
using GetProperties to get an array of "PropertyInfo" objects you could use
the PropertyInfo property "Name". I do not recommend this though as you would
be hard coding property names to compare to. I would add a custom attribute
to the property that has a Name property itself (or some other marker you can
use to distinguish between which Address. Then when you get a property of
type Address to a GetCustomAttributes and iterate over these looking for the
one you added. This should make the code more readable and supportable too.
Hope this helps.
--
Thom
"Jason Reynolds" wrote:

(using .net 2.0)

Say you have a class structure like this:

class Address
...
end class

class Person
FirstName
LastName
MailingAddress as Address
BillingAddress as Address
end class

I'm using reflection to pull out the values at runtime, but I'm having
trouble when I dive into an address. When I'm traversing the object I know
when the type is address and I can get and set values on that instance, but I
can't figure a way to know if I'm looking at the mailing address or the
billing address. Is there a way to get the instance name of an object at
runtime? I've thought about setting a name property in the object, but
that's a bit of a hack and makes things much less reusable. Thanks in
advance.

[Jon Skeet [C# MVP]]

On May 9, 3:07 pm, Jason Reynolds
<[e-mail]:

<snip>

class Person
FirstName
LastName
MailingAddress as Address
BillingAddress as Address
end class

I'm using reflection to pull out the values at runtime, but I'm having
trouble when I dive into an address. When I'm traversing the object I know
when the type is address and I can get and set values on that instance, but I
can't figure a way to know if I'm looking at the mailing address or the
billing address. Is there a way to get the instance name of an object at
runtime? I've thought about setting a name property in the object, but
that's a bit of a hack and makes things much less reusable. Thanks in
advance.

There's no such thing as an "instance name" of an object. In your
above example, MailingAddress and BillingAddress could both be
references to the same object. What would you want your code to do in
that case?

Jon

[Jon Skeet [C# MVP]]

On May 9, 4:01 pm, Jason Reynolds
<[e-mail]:

Thanks for the response. I like the attribute idea. I was thinking along
the lines of having a name property in the address class, but didn't like the
idea at all. If I understand you correctly, you are suggesting putting
attributes on the MailingAddress and BillingAddress properties in the Person
class. I like this approach much better, but it's still not as clean as I'm
hoping for.

Going back to the PropertyInfo technique, when I loop through the
PropertyInfo array and access name I get something like
"CSQ.BusinessObjects.Address" (this is my namespace) which is the type not
the instance name. What I'm looking for is "Person.MailingAddress".

You shouldn't get the type name if you ask PropertyInfo for its name -
you'll get the property name. That won't be "Person.MailingAddress",
it'll just be "MailingAddress".

Check that you're not using PropertyInfo.PropertyType.Name.

Jon

[=?Utf-8?B?SmFzb24gUmV5bm9sZHM=?=]

Is there such thing as an instance? If so, would what I'm calling the
instance name actually be a property which points to an instance?

What my problem boils down to is having controls on a page such as text
boxes with the following ids:

person_firstname
person_mailingaddress_city
person_billingaddress_city

and matching these at run time with properties in business objects.

It would be incredibly handy to have a solution to this problem, it would
save a lot of time by eliminating a lot of brain dead type coding, but
perhaps I need to take a step back and consider a different approach.

"Jon Skeet [C# MVP]" wrote:

On May 9, 3:07 pm, Jason Reynolds
<[e-mail]:

<snip>

class Person
FirstName
LastName
MailingAddress as Address
BillingAddress as Address
end class

I'm using reflection to pull out the values at runtime, but I'm having
trouble when I dive into an address. When I'm traversing the object I know
when the type is address and I can get and set values on that instance, but I
can't figure a way to know if I'm looking at the mailing address or the
billing address. Is there a way to get the instance name of an object at
runtime? I've thought about setting a name property in the object, but
that's a bit of a hack and makes things much less reusable. Thanks in
advance.

There's no such thing as an "instance name" of an object. In your
above example, MailingAddress and BillingAddress could both be
references to the same object. What would you want your code to do in
that case?

Jon

[Jon Skeet [C# MVP]]

On May 9, 4:47 pm, Jason Reynolds
<[e-mail]:

Is there such thing as an instance?

Yes - the instance is the object.

If so, would what I'm calling the
instance name actually be a property which points to an instance?

I suspect so. The *property* certainly has a name, but the object
(instance) itself doesn't.

It sounds like using the name of the property is what you're after.

Jon