Object Aggregation Of Inherited Classes?
Oct 4, 2011Object aggregation of inherited classes
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Understanding Object Aggregation And Databases
Aug 24, 2010I have a situation in a program I'm writing where I'm not sure of the best way of coding a couple of objects and was hoping for a few pointers.I am using VB.NET 2003, so F/wrk v1.1. My business is horticultural in nature and I'm trying to help streamline the business with a new order fulfillment app.In my program, I have products. Some products don't have any component parts, but others are made up of a selection of plants.For example: we sell a trowel, which obviously doesn't have any component parts. But we also sell a large vegetable garden, which is made up of, say, 20 rocket plants, 30 salad plants, 5 spring onions, etc.[code]I believe the ProductContents table is technically referred to as a 'join table'?
I have written the classes in VB.NET which load, save, edit the Products and the Plants. I also have Manager classes which store collections of these objects (ProductMgr, PlantMgr).I have dealt with situations before with join tables where there are only two columns which are both FKs and both make up a composite PK (ie - to express a one-to-many relationship). This is pretty straightforward (using my product/plant tables as an example) because when I load an individual Product from the database, I also run a second SELECT query which returns any PlantIDs associated with that PlantID from ProductContents. I store that in an array of integers within the Product object. I can then load Plants from the PlantMgr object based on the PlantIDs stored in this array. I kind-of do the reverse when I save the Product to the database, I run a second INSERT query which updates the ProductContents table with the Plants associated with the Product.Where I'm getting stuck is with the inclusion of the extra 'Quantity' column. I can no longer store the PlantIDs in an array of Integers because I also need to store the Quantity associated with that Plant. I also can't use the PlantMgr object any more (to express which Plants are in each Product) because it also doesn't include any information about Quantity.I was just wondering if there is a standard way of handling this kind of situation, where I have a 'join table' which also includes extra columns as well as the two columns that identify the join.
.net - Inherited Classes Returning Different Values?
Jun 25, 2010This is more of a conceptual question than anything.
I have a base class called "RawReader".
It sets up the framework for classes to inherit it and read in specific data systems.
For example, I want an app read in a known format of FoxPro database, a CSV file, or a SQL database (there is about 8 more formats currently), then transfer it over a webservice and create a SQL database from it.
I have everything working with CSV, FoxPro, Access, Excel, etc... Easy enough.
The classes that inherit RawReader, like RawCSV, RawFoxPro, RawAccess all return a struct that contains a dataset as one of the members. The dataset contains the data from the raw system. The webservice receives this struct and creates sql tables and loads the data into it. This has already been coded and works great.
My issue now comes to reading in SQL. Obviously, I could follow the same path, read the remote SQL DB into a dataset, transfer the dataset as above, etc... My "issue" comes in where I feel like it doesnt make much sense to transfer a SQL db to a dataset, transfer it through the webservice, and then try to programmatically recreate the SQL database. I feel like I lose a lot of the granular details from the SQL database (field sizes, extended info, etc..) It seems easier in practice to just create a backup of the database, convert it to a stream object and transfer the backup over to the webservice. But this is where the problem lies...
Since all of the classes inherit from the base class, they are set up to return a DataSet. The hack-ish way would be to just add a stream object to the return struct and in my webservice add other code to make a special case for SQL sources, but I was trying to avoid that.
Any thoughts on the "proper" way to go about something like this?
Invalid Cast While Using Inherited Classes?
Jul 28, 2010I create an application in both C#.NET and VB.NET
When I inherit a C# class in VB I want to be able to set an instance of the VB class to be equal to that from a C# instance.
public
class
SomeClass
[Code].....
Suppressing Properties In Inherited Classes?
Dec 3, 2008Seems like you should be able to Suppress Properties in inherited classes. How do you do it?
View 7 Replies[2008] Base Class Inherited By 2 Derived Classes
Jan 30, 2009i've finally got round to learning about classes and inheritance, but i'm not sure how to proceed. i have a base class Employee, which is inherited by 2 derived classes. how do i use the same Employee class in both derived classes? obviously if i write a sub new for both of them + declare a new Employee class, they won't be using the same class. heres my Employee class:
[Code]....
Reflection - Function Witch Return Type Is The Class Itself In Inherited Classes?
Dec 10, 2011I have a parent class that is also a factory. For example:
Public Class Factory
Public Function clone() as Factory
' Some logic here
[code].....
.net - Apply Common Codes In Inherited BaseEdit For Inheriting Classes - In Order To Build A Read Only User?
Feb 20, 2012In businesslayer, there is a inherited Class Called BaseEdit which contains contractor and base properties. There are about 30 CustomEdit (inheriting classes), all of them has methods "Load","Save" and "Delete". The require for this existing system is to add a readonly user. Possible solutions considering the cost of works:
1) Modify the BaseEdit so all CustomEdit can stay the same. The system will check 'user role' in session by using httpcontext then to accept or reject the user's action.
[Code]...
Change Property Of An Inherited Object
Oct 31, 2010On form1 I put a picturebox from the toolbox.[code]Is it possible to set picturebox.visible=true of the inherited picturebox?
View 1 RepliesPassing Base Object Type When Using Inherited One?
Oct 8, 2010I have a project that has mainly two objects, both inheriting from a base. Like this:
Public Class Vehicle
Property Model As String
Property Make As String[code].....
The above function doesn't work because myVehicle is a Vehicle, not a Truck.Is there a way I can pass around a Vehicle type and have the IDE know which type to use? Or am I completely missing a better way to do this?
Object Reference Not Set To An Instance Of An Object With A Class With An Array Of Classes As A Member?
Aug 6, 2010Here is the structure that I have:
Friend Class StandardFormatFile
Friend fileType As String
Friend numberOfSeries As Integer
[code].....
.net - Extending ENUM Valus Inherited From Base Object?
Jun 14, 2010If I defined a ENUM in a base object with serveral default values. When I inherit from the base object I want to add more options the the ENUM list which are specific to the inheriting object.
For example my base could have a ENUM called Direction with values:
None
ALL
Stop
Start
I create a new class call Compass which inherits the base class and what to add the following to the ENUM Direction. I create a new class call Navigation which inherits the base class and what to add the following to the ENUM Direction. So, In my inheriting class haow do I extend the ENUM.
Perform An Aggregation On A DataTable With Linq In .net
Dec 22, 2009I wish to output an IEnumerable type (dictionary(of T) would be perfect, otherwise a datatable would be acceptable) that provides an aggregation of the data within the datatable.In SQL I would write the query as such: select groupByColumn, sum(someNumber) from myTable group by groupByColumn
In VB.NET the closest I have got to this (achieved using information here) is: dt is a datatable containing two columns, referred to by index in p below Dim q = From p In dt Group p By p(0) Into Sum(p(1)) Select p(0), SumOfNumber = Sum
However I receive error: "Range variable name can be inferred only from a simple or qualified name with no arguments." on the p(0) element. Therefore my question is as follows:How can I resolve this error? How do I process the result (q) as an IEnumerable type? Life isn't made any easier because I'm using Linq in unfamiliar vb.net. Many examples are in C#, but I haven't really come across anything suitable even in C#.
.net - Storing An Object To Use In Multiple Classes?
Mar 23, 2010I am wondering the best way to store an object in memory that is used in a lot of classes throughout an application. We have multiple databases, 1 per customer. We also have a master table and each row is detailed information about the databases such as database name, server IP it's located and a few config settings.
I have an application that loops through those multiple databases and runs some updates on them. The settings I mentioned above are updated each loop iteration into memory. The application then runs through series of processes that include multiple classes using this data. The data never changes during the processes, only during the loop iteration.
The variables are related to a customer, so I have them stored in a customer class. I suppose I could make all of the members shared or should I use a singleton for the customer class? I've never actually used a singleton, only read they are good in this type of situation. Are there better solutions to this type of scenario? Also, I could have plans for this application to be multithreaded later.
.net - Do Classes Serialized As Object Lose Their Type Information
Apr 2, 2012I have a serializable Message class that has a Data As Object property that I'm using as a generic holder for information to be sent via a system that uses a combination of push technology and/or IPC to communicate with any other programs that are interested in the information. This allows the communication piece to be agnostic of the information it transmits.
I was serializing this Data As Object as a Byte[], since I was worried about how an Object being serialized and transmitted across the network would behave on the other side. However, when deserializing I get errors about being unable to find the assembly for the types stored within my Data As Object property, because I'm deserializing in the assembly that contains the Message class... not the assembly that contains the type that Data As Object originally was.I was wondering if I'd lose the type information and be unable to cast it back to the type I want at the other end. Perhaps it's not possible to pass a type as an Object via another assembly without it knowing about my type?
Serializing To Binary Formatter A Complex Object With WPF Classes?
Feb 17, 2012i have a complex object that holds a WPF Canvas with many child canvases, rectangles and, lines. The object includes some home grown classes as well. The main object and the home grown classes have the <Serializable()> attribute set. I tried the general formatter.Serialize(strm, rb_x) to serialize the object to a memory stream. I then found out that WPF classes are set as serializable. So after some research I discovered the System.Runtime.Serialization and found a generic Serialization Surrogate.So after some debugging I was able to serialize the object to a memory stream then copied the stream to an array of bytes then store that array in an OLE field in an MS Access table.
When I read back the access record and copy the OLE field byte array back to a memory stream and then de-serialize it back to the object I get a SerializationException "Error binding to target method."
So question #1 - is what I am trying even possible?Question #2, (assuming #1 is yes) do I need to do something special with WPF Baml type objects.
Base Form And Inherited Other Forms From It - Don't See Those Changes Take Effect In My Inherited Forms?
Jun 24, 2010I have a base form and I inherit other forms from it. However, if i go back and change say the size of the base form, I don't see those changes take effect in my inherited forms. Does anyone know why that is? Is there a solution to this issue?So as far as design is goes, what exactly gets inherited by other forms?
View 9 Replies"upgrade" An Object To An Inherited Class, And Keep All The Base Class's Property Values?
Jul 5, 2010bare with me during this silly example. :-) Let's say I have a class like this:
Public Class Animal
Public iLegs as int32 ' Number of legs
Public bWings as Boolean ' Wings? Yes/No
End Class
And another class that inherits the "Animal" class and adds one more property:
Public Class ScaryAnimal
Inherits Animal
Public iScariness as int32 ' 0-100, how scary is it?
End Class
Now, if I have an instance of "Animal" with some values in it, and I decide I want to cast it to a ScaryAnimal for some reason, how do I do that without having to create a new instance of "ScaryAnimal" and copy each property value?Basically I'm looking for a way to do this, without having to write the lines marked with '*** below:
[Code]...
Use LINQ To Filter Collection Of Nested Classes To Yield Dictionary Of Unique Properties Of Those Classes?
Jan 23, 2012I have two classes, one nested in the other. [code]Neither "Name" or "ID" are unique between operations and records.I wish to construct a dictionary using LINQ = Dictionary(Of String, Of List(Of Integer), whereby the keys are uniqe examples of Names in my collection and the values are the collective set of distinct IDs that are associated with those names.
View 2 RepliesVS 2010 Structure Classes So That The User Interfaces Though A Single Class While The Supporting Classes Are Hidden From Their View?
Jun 13, 2012How can I structure my classes so that the user interfaces though a single class while the supporting classes are hidden from their view? I think its best understood in an example:
Public Class MyInterface
Public Economic as EconomicClass
Public Sub New()
MyBase.New()
[code].....
So you might ask why am I even separating them? It's strictly for others who will be working with this interface. I need to funnel them though a logical structure:
interface.Economic.MyMethod
interface.Currency.MyMethod
etc
This way everything is already handled for them in the background and they only need to run the method they need. I don't know if I can have it both ways in VB.NET.
VS 2010 Calling Subs And Functions Within Classes That Are Within Classes?
Oct 24, 2009Here is some example code of what I mean:
vb
Public Class Form1
Private Sub Button1_Click(ByVal sender as Object, e as systemEventArgs) Handles Button1.Click
[Code]....
Derived Classes Cannot Raise Base Classes
Jul 10, 2009I m trying to raise Click event of Textbox explictly but I m getting "Derived classes cannot raise base classes" error.[code]....
View 1 RepliesLoop And Enumerate Properties Of Nested Classes In Nested Classes?
Sep 24, 2010so far i got
code
For Each item As Reflection.FieldInfo In GetType(NameSpace.ClassWithNestedClasses).GetFields
rtfAppend(item.Name & ":" & Tab & item.GetValue(Me))
Next
For Each item As Reflection.PropertyInfo In GetType(NameSpace.ClassWithNestedClasses).GetProperties()
[code]...
which gets me the simple string vars and properties of my top class, but how can i apply this to loop through all sub classes and get there vars and props?
VB XML Classes Vs String Classes?
Oct 13, 2011Searching the internet finds no less than 700 different ways and opinions to accomplish what I'm trying to do, and I would just like to know the simplest, most bullet-proof way possible.
[Code]...
I simply want to extract the string "bar," which is inside <hostName></hostName>I can do this easily enough with simple string functions, but I'd like to do it with one of the .NET XML classes/methods.
Bug In Inherited Controls?
Aug 22, 2009on the custom inherited control i created, i noticed that when i bind my custom property to a data column, if that data column returns a value other than Null it always return a datarowstate of modified even if there were no changes. to produce this issue, i have below a sample code for a test inherited control
Imports System.Windows.Forms
Imports System.ComponentModel
Public Class TestControl
[code].....
Access Class From Inherited?
Oct 14, 2011I have two classes[code]...
How can I modify class1 in a sub in class2?
Closing An Inherited Form ?
Oct 27, 2009I am having a problem with closing a form which I have inherited I have a form called frmAddForm_Simple, which contains 4 main controls (A Data Grid, A Save Button, A Close Button and a Text Box). The idea around the form is to create a form which could be used for inputting of many different types of data which are all entered in the same way (i.e. to add a new row to a database for [Status] table or [Location] table, all of which contain 2 columns in the database (an [Id] and a [value]). On the form I have a property called _FormChanged, which when the textbox text changes, sets the property to True. I then have the following code on the Close Button:-
Public Sub btnClose_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnClose.Click
If _FormChanged Then
If MessageBox.Show("Are you sure you want to close and discard any changes?", "Discard Changes",
[CODE]...
Is opened as a dialog (ShowDialog) and when I go to close the inherited form (by click on btnClose) and answer No to the above MessageBox the form closes anyway. Using the Debugged I have worked out that the following events occur in sequence (all of which runs in the Master Form mentioned above):-
1) btnClose_Click sub Routine runs
2) I answer No to the question do I want to close the form
3) The debugger steps over the Me.Close() line (as expected)
4) The debugger jumps up to the Sub Initialise (where ShowDialog was called from) and closes the form.
So at no point has the debugger even ran a line of code which reads Me.Close(), but the form closes anyway so Im fairly confused as to why the form should close.
My Master Form (frmAddForm_Simple) Code:-
Public Class frmAddForm_Simple
Private _FormChanged As Boolean = False
Private _FormLoading As Boolean = False
[CODE].............................
Create, And Use An Inherited Treenode?
Jun 24, 2010I'm confused regarding the MS examples for inheriting a treenode. I have created the following class to allow an addtion description field on the treenode:-
[Code]...
IDE :: Web Browser - Inherited Control And COM?
Mar 9, 2009[code].....
View 1 RepliesInherited Form Cannot Be Loaded
Sep 12, 2009I am trying to create an inherited form- when I go to add it, I get the following message- "CustomerInformation --- The base class 'Object' could not be loaded. Ensure the assembly has been referenced and that all projects have been built"
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