Charlotte Foust
cfoust at infostatsystems.com
Tue Nov 13 11:24:31 CST 2007
John,
I think you may be reinventing the wheel, or at least the roller.
DataAdapters will handle all or most of this for you. The Adapter/typed
dataset KNOWS what the fields are, what the field types are, whether it
allows nulls, whether it's a key field, whether the field or record is
read only, etc. Obviously, I'm missing something here because I work
with tables that already exist or with xml data sources. We use SQL
scripts to build new databases/tables in SQL Server. You can build an
adapter for a non-existent table and then use it to write the table as
well.
Charlotte Foust
-----Original Message-----
From: dba-vb-bounces at databaseadvisors.com
[mailto:dba-vb-bounces at databaseadvisors.com] On Behalf Of jwcolby
Sent: Tuesday, November 13, 2007 9:14 AM
To: dba-vb at databaseadvisors.com
Subject: Re: [dba-VB] Iterating class properties
Charlotte, Drew,
What I am trying to accomplish is to be able to dynamically, at run
time, get a list of all properties of a class. This allows me to
compare values between any two (or more) class instances of any class.
Suppose (for
example) I wanted to merge 4 records in a table into a single table. I
don't know what the field names are but I want to load the table records
into classes and then go comparing one record against the next.
Suppose I want to know the data type of a property of a class at run
time?
I have a class I want to persist to a table. The table does not exist
yet.
I need to find out what data the table holds, build a table with fields
to hold that data. I need to discover what the properties of the class
are (what data is read / writeable) and what types of data do they hold?
I can then build SQL statements to build a table to match the class,
right then, on the fly. Pass in a class, pop out a table in SQL Server.
I have found the answer it seems. I am not sure I understand it yet
though.
John W. Colby
Colby Consulting
www.ColbyConsulting.com
-----Original Message-----
From: dba-vb-bounces at databaseadvisors.com
[mailto:dba-vb-bounces at databaseadvisors.com] On Behalf Of Drew Wutka
Sent: Tuesday, November 13, 2007 11:55 AM
To: dba-vb at databaseadvisors.com
Subject: Re: [dba-VB] Iterating class properties
What are you trying to accomplish? I don't use .Net very often, still
do most of my stuff in VB 6. But I wanted a way to dynamically capture
my class properties.
For example, let's say I had Widget, and it had Height and Width
properties.
I wanted to be able to do this:
Dim wd as Widget
Set wd=new Widget
Wd.Properties("Height")=10
Or
Dim wd as Widget
Dim I as long
Set wd=new Widget
For i=1 to wd.Properties.Count
Wd.Properties(i)=15
Next i
I don't know if .Net has this capability, VB 6 didn't natively, but I
was able to 'spoof' the ability. I created an Add-in that let's me
create a Properties property for a class. When you run the Add-in, it
goes through all of the properties in your class, and creates statements
to simulate the abilities above. It's adding a lot of extra code to do
this, but in some situations I have run into, it's worth it...plus, all
the properties are left alone, so I can use them like I normally would.
Drew
-----Original Message-----
From: dba-vb-bounces at databaseadvisors.com
[mailto:dba-vb-bounces at databaseadvisors.com] On Behalf Of jwcolby
Sent: Tuesday, November 13, 2007 6:43 AM
To: dba-vb at databaseadvisors.com
Subject: [dba-VB] Iterating class properties
Does anyone know a way to iterate the properties of a class in VB.Net or
C#.Net (or in .Net in general)? There is built-in functionality to
store classes out to XML files and this stuff does exactly that,
apparently using only the Get/Let statements, i.e. if there is not both
a get and let statement for a property then the process fails to convert
that property to XML.
So if MS does it, is that capability publicly available? Is there a
property iterator buried in the innards of the class object?
John W. Colby
Colby Consulting
www.ColbyConsulting.com
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