.net - Handling Different DbType Enums In Database-Agnostic Architecture?
Apr 17, 2012
Here's my current set-up:
Public Interface IDatabase
Function CreateParameter(name as String, dbType as <dbTypeEnumeration>)
End Interface
[Code]....
The problem here is what exactly is dbTypeEnumeration. In the example above, it's simply a placeholder to what my problem is. Since we use both Oracle and SQL Server databases, the DbTypes are different depending on the database being used. For Oracle, the OracleClient object has its own OracleDbType enumeration with types. SQL Server also has its own enumeration.
My question is: is it possible to show those database-specific enumerations depending on which repository is injected into the DatabaseService constructor? If not, what's the best way to go about this? I want to separate the two databases, share logic, and allow for future development, ala the interface as a code contract for that development.
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Nov 5, 2009
I need to write an app that that will iterate over our database, and perform various anaylsis on each record. In order to do this (partially for the learning exercise in creating plugin support) I want to use a Plugin model.
Currently, I have a simple Interface in my main app, which plugins can Implement. My app then loads all DLL's in a folder looking for ones implementing the Interface.
As you can see in the pseudo-code below, I have to keep performing a loop through all loaded plugins calling the process methods.
Sub ProcessData()
For Each Record In MyDataSet
For Each Plugin In MyPluginCollection
[Code].....
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Jul 20, 2011
I need help in understanding this architecture. The person who wrote it is long gone and I'm stuck to figure it out. We are creating an object in some code from some random workflow in the web application (unimportant for my question). The object is being instantiated from a class found in a Designer.vb file. I couldn't initially see the file until I clicked the "show all files" in Solution Explorer in Visual Studio. There are 3 files linked together.. a *.xsd file, a *.Designer.vb file and a *.xsx file. The *.Designer.vb file looks to be auto-generated.
Goal:Get dbo.note.text from the dbo.note table column and place it in the dbo.exportnote.text column. I just don't understand how it's connecting to the database and getting the data from the dbo.note.text field. I want to make the query more specific (possibly put a where clause on it). But really I just want to understand how it's communicating with the database. Most of the code uses stored procedures. So I'm confused on the architecture. What would be really cool is if you can explain how this code was autogenerated. It appears that the *.xsd file is an XML file when I "View in Browser" from the Solution Explorer.Code to instantiate object of designer class:
[code]...
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Jan 19, 2010
I have a table, lets call it Objects. It has a predefined set of records looking like this:
ObjectId ObjectName
1 Salmon
2 Trout
3 Seabass
4 Shark
Etc..
So, this I would like to implement somehow as an enum. But what's the best way, implement it in the database creating tables for it or in the application logic in an CommonEnums codebehind file etc?
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Aug 3, 2011
I thought that enums in VB and C# where the same or at least very similar. Then today I stumbled across a bug in our VB code. The following VB code compiles and runs with no issues:
Enum Cars
Subaru
Volvo
End Enum
[code]....
Why does the VB version not catch the type mismatch? Are enum in VB and C# different?
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May 17, 2011
I have a table called Foo and I have two columns: Lorem and Ipsum, so the scheme of the table is:
Foo(Lorem, IpsumID)
I also have a table called IpsumTypes, which looks like this:
IpsumTypes(IpsumID, IpsumName)
I would like to write a LINQ query which will have the following result:
Headers: Lorem, IpsumName1, IpsumName2, ..., IpsumNamen
Values: Loremi, count(IpsumName1), ..., count(IpsumNamen)
Each row represents a group of Lorem value and the number of each possible IpsumID in the group. New rows can be added to the IpsumTypes table, rows can be deleted too, so I need dynamically generated columns, because at the time of writing the code I'm not aware of the possible values of Ipsum. How can I achieve this? Is there a magical Linq query which solves this problem, or should I get the values from the database and parse them separately, if speed counts?
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Aug 9, 2009
if i miss to set dbtype of my parameters (common.dbparameter) it works fine again?Is necessary to explain dbtype or not?
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Jun 22, 2010
So I have this weird issue where I set a SqlParameter.DbType field = to a SqlDbType.Decimal, but instead it sets it to a SqlDbType.DateTime. I'm going to include 2 screen shots from the debugger one line after the set statement. As you can see when I hover over (just after the execution of that line), it set the param.DbType to the wrong value. I can only assume that the param.DbType has code that incorrectly changing the type. How can param.DbType become a SqlDbType.DateTime when the varable I'm setting it to is a SqlDbType.Decimal? I'm targeting the .Net Framework 3.5.
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Apr 4, 2012
When I looked at the database record, the datetime saves like this: 4/6/2012 04:42:28 PM
because I've save it using dbtype.string
Now, I'm getting the date only, not including time, this is my code:
Private Sub getpapererror(ByVal ddate As String)
Dim sqlstr As String = "select * from perror where date(ddate) = $xddate"
Dim sqlcmd As New SQLiteCommand(sqlstr, mycon)
[Code].....
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Aug 22, 2011
For no apparent reason, I'm getting an exception on this line in my when the table adapter attempts to fill my dataset.
Me.TblFuelTableAdapter.Fill(Me.CCFuelDataSet.tblFuel)
The error reads:
Quote:
System.ArgumentException: No mapping exists from DbType Object to a known SqlDbtype.
This error just came out-of-the-blue. If I 'Preview' the data though the DataSet directly (using the Fill() query), the data returns fine...
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Jan 8, 2009
I haven't done any programming in a while, and I have pretty much 0 experience with databases, so I'm hoping I can get some guidance with what I'm trying to achieve.I have a class (or want to have) which represents a person, for each person there's multiple dates, and for each date there's multiple events which have properties like time, place, duty, etc. I want to be able to save and load this from a database using a form. I want it to be able to function where I can type in the person's name and it will load all the data into the form, which has a combo box for the different dates and events, and when I select a different date and/or event I want the data to change correspondingly.
If someone could just give me a push in the right direction as to where I should be looking for help in achieving that I would really appreciate it. I don't have the class made to do any of that, just an idea of how it will function. I haven't worked much with classes, so I'm not sure how to approach it. Meaning I need guidance with classes and databases alike.
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Apr 16, 2010
I need some basic assistance understanding how to mess with bytes. And when I say basic, I mean dumb it down for me, I'm a self taught hobbiest mostly and only spent 4 years proffessionally in development. And that 4 years was a database programmer handling the connecting, retreiving and inserting of data into various databases.
I can't honestly think of the last time I had to do anything with Bytes, but I do know that when I did, all of the functions that actually did anything were written by someone else. So start off, I've been trying to handle them like strings, and that's not working for me (you probably guessed that).
[Code]...
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Jan 20, 2012
I have a text file contains delimited records.
1243;jhhf';982u4k;9u2349;huf8
kij;9238u;98ur23;jfwf;03i24
I need to replace the value of 4th part of every record with the value returned from SQL database (Select X from T where C='4Th part from the flatfile').
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Mar 4, 2011
I want to handle errors that might occur when user tries to connect to database. I don't know how to do that.This is my connection string used all over the program:
Using connection As New OleDb.OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + txtFilePath.Text + ";Jet OLEDB:Database Password=" + txtFilePassword.Text + ";")
There are a few errors that i faced them myself:
[code].....
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Feb 15, 2010
Until asking a question on here I never considered (enums) to be a "bad thing." For those out there that consider them not to be best practice, what are some approachs/patterns for avoiding their use in code?
Edit:
public Enum SomeStatus
Approved = 1
Denied = 2
Pending =3
end Enum
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Jan 14, 2010
We have legacy character codes that we want to store as numbers in a new system. To increase readibility and general understanding in the code for devs making the migration, I want to do Enums like this..
[Code]...
With this setup, the code will be readable (imagine If Record.Status = Status.Open), and yet the values will be stored in the database as small numbers so it will be efficient. However... I am a VB.NET guy, but everybody wants to code in C#, so I need this sort of structure in C#.After Googling, I discovered the the general .NET equivalent of AscW is Convert.ToInt32("C"). When I try to use that statement in an enum, I get the compiler error "Constant Expression Required".
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Oct 4, 2011
I have an enum and a usercontrol, both in the same assembly (a plain .NET 4 web site). In the Constants class:public Enum CrudOperations Add Edit Delete. This controls the columns in a GridView on a UserControl via a property on the UserControl
[Code]...
In C#, I've specified the columns to show with markup as Mode="Edit,Delete", but in VB.NET, this does nothing. The only way I can get anything to show is with the codebehind, but if on the containing page I use userGrid.Mode = CrudOperations.Edit And CrudOperations.Delete, I get all the columns (there's also a delete column), but userGrid.Mode = CrudOperations.Edit Or CrudOperations.Delete shows nothing.
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Mar 10, 2011
I have a public property, "Status" that is an enum. I have a setter method that changes the status and raises the PropertyChanged event. However, the WinForms user interface is not properly updating. I'm pretty sure it's because Status is an enum. Although I was thinking enum was a reference type but I guess it's a value type. Does INotifyPropertyChanged work the same with reference and value types?
[Code]...
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Nov 25, 2008
I work for a web hosting company and was handed a VB script which I apparently have to compile with some updated settings by 1 of our clients who knows less about it than I do. But when trying to compile the code I receive an error "'Enums.NoticeType' is not defined". As expected I haven't a clue. Am I missing some of the code, or do I have to add some libraries in my Visual Basic 2008 Express Edition? I have pasted the line of code below. If requested I can provide the whole script.
Code:
Public Function UpdateNotices(ByVal intNoticeID As Integer,
ByVal strNoticeTitle As String, ByVal dtDateFrom As Date, ByVal dtDateTo
As Date, ByVal intTypeID As Enums.NoticeType, ByVal boolPrimaryItem As
Boolean, ByVal boolActive As Boolean) As Int32
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Oct 20, 2011
I have a solution with multiple projects, some of the projects are written in VB, some in C#. I am wondering if there's a way to use interfaces and/or enums written in VB in C# classes? My C# code below doesn't compile, however I am able to see the interface in intellisense.
[Code]...
P.S It's a console/service application, not ASP.Net (where I know it's doable).UPD: Sorry guys, was missing a reference to the project with the interface. It's fixed now. I think the thing that in VB projects references are done slightly different than in C# confused me.
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Sep 23, 2010
I have a base class with the the following enum and property:
[Code]...
First off, how do I do this - is it by simply overloading it? And secondly will my original property pick up the new enum automatically when using the derived class or will I need to overload that too?
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Nov 22, 2010
We have a common component in our source which contains all the enums (approx 300!) for a very large application.Is there any way, using either C# or VB.NET, to iterate through all of them in order to perform an action on each one?
How to iterate all "public string" properties in a .net class is almost relevant but the enums I am dealing with are a mix of types.
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Feb 16, 2012
I'm using LuaInterface for .NET to create Windows Forms objects. This works pretty good except for one thing:I want to use the Anchor property of Control to make them resize automatically. If I only set one of the Anchors (e.g. only AnchorStyles.Top), it works, but this doesn't really make sense. I have to set more than one Anchor, which is done by combining them with "bit-wise or" (or by just adding them numerically).
In VB.Net both works:
Dim myLabel As New Label()
myLabel.Anchor = AnchorStyles.Top[code]....
which is in a sense correct as "LuaInterface treats enumeration values as fields of the corresponding enumeration typ" (says LuaInterface: Scripting the .NET CLR with Lua).It is also not possible to assign the value as a number:
myLabel.Anchor = 15 -- 15 = 8 + 4 + 2 + 1 = Top+Left+Right+Bottom
This time, the error message is rather unspecific:
LuaInterface.LuaException: function
Is there a possibility to typecast the number to the correct enumeration type in Lua?
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Jan 27, 2010
What would the folowing VB.NET enum definition look like in C#? [code]
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Apr 16, 2010
Is it guaranteed that the numeric values for an Enum with only uninitialized values start at zero and increment by one in the order defined?
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Mar 10, 2009
I want to add a setting that uses an enum defined in form1.vb. All the research I've done suggests support for enum type settings is built-in and handled automatically by the VS IDE ... I assume this means it's as easy as defining font or color settings. However, I'm not having much. Are any of you gurus aware of how to set up an enum setting via the Project Settings UI?
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Jul 22, 2010
I realize this is probably trivial, but for some reason I'm not sure how to pull it off. Say I have the following enum:
Public Enum FlagType
Docs
Email
[Code]....
How do I then at runtime determine which flags where set for flags? In this example, it should be Docs and Email.
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Jan 9, 2012
Is there a way to use strings in Enums like the example below:
Enum myEnum
val1 = "some string 1"
val2 = "some string 2"
val3 = "some string etc"
End Enum
It seems like you can only use integers for the underlying values.
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Nov 6, 2009
I was wondering does anyone know where i can find some good books and or articles covering the architecture and design of OOP applications. Also I need a book that explains how to structure an application as it relates to the data tier, business logic tier, and the front end.
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Jun 3, 2009
In the first comment (by J.W.) to this question: Using ObjectDataSource and DataObjectTypeName, How Do You Handle Delete Methods With Just An Id Parameter?, it is said that using ObjectDataSource is a bad design. What is considered good design for well-architected ASP.NET applications?
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