I'd like to try and expose some connections for a webpart at runtime, at compile time I don't know what they are, and I'm wondering if anyone can provide any suggestions on where to start.
All the examples I've read seem to do so statically using [ConnectionConsumer] and [ConnectionProvider] which obviously needs to be done in code, I don't however know what I need to expose at this point in time.
My use case would be something like a grid that uses a DataTable. The DataTable is retrieved by using a SQL statement:
select * from myTable
The connections I want to expose are when this changes to
select * from myTable where columnA = myConnection1
At this point I want to expose a connection for my WebPart called 'myConnection1', if I add multiple where clauses I want multiple connections that can be linked from other WebParts.
EDIT
An example of this would be like how ReportingServices within SharePoint handles connections. It seems to use a custom WebPartManager that determines at runtime the number, names and types of connections that need exposing.
You can create connections between web parts dynamically:
wpMgr.ConnectWebParts(wp1, cp1, wp2, cp2)
Ted Pattison: http://msdn.microsoft.com/en-us/magazine/cc188696.aspx#S6
Not sure what is dynamic in your question:
-the schema of the data that flows through the connections OR
-the creation of these connections from provider to consumer web parts at runtime?
Hope this helps?
In the end I determined that the best way was to use the IWebPartParameters interface and expose them manually.
http://blog.mindbusiness.de/blog/2011/09/05/implementation-of-iwebpartparameters-web-part/
Related
I'm currently handling a .Net system that was developed in Linq for its data retrieval structure. This system was developed by other developers last time and I'm dealing a big problem now.
One of the bad practice (or i just not sure why must the developer do that) i found from this system is that, inside /AppData/DataContext/, there are alot of .dbml files and in the .designer.vb, for example Product.designer.vb file, consists of this piece of code:
Private Shared mappingSource As System.Data.Linq.Mapping.MappingSource = New AttributeMappingSource
Public Sub New()
MyBase.New(Global.System.Configuration.ConfigurationManager.ConnectionStrings("DBconstr").ConnectionString, mappingSource)
OnCreated
End Sub
My current major challenge is, I need to change to a new connection string name for all DBconstr and point to another database while keeping the current "Dbconstr" setting in web.config. There are over 400 lines in the entire system I need to find and replace if i have to do it manually. So I need advice if there is any way i can change all hard-coded connection string using one or few direct methods instead of changing all 400 plus lines manually?
I had thought about calling certain method in .Master page and override the value of .ConnectionString for all the child pages but not sure if this is possible.
Please advice. Thanks
You should have a look at this: http://blogs.msdn.com/b/webdev/archive/2009/05/04/web-deployment-web-config-transformation.aspx. It explains how to use web.config transformation. It basically allows modifying the value of a setting (ie. connection strings) depending on your solution/build configuration.
Modifying the configuration file "on the fly" is much easier than trying to modify it in the code.
You should also check these two answers I provided on the same topic:
How to have different web.config settings for my local machine? -
https://stackoverflow.com/a/19294499/375304
Applying web.config transformations locally - https://stackoverflow.com/a/19301084/375304
I've been developing an app which uses strongly typed datasets and stored procedures. I've just graduated and this was the method that was sold to us as the way to go. I'm starting to have severe doubts.
My client has advised me that he might change from SQL Server to MySQL. From what I've read it might be better to not use stored procedures as migrating could become more difficult. So anyhow I've just implemented a new table adapter query using the wizard and selected Use SQL Statements rather than Create new stored procedure.
My call to the query
Intranet.administratorsDataTable dt = taAdministrators.GetAdministrators();
now generates this error:
executereader requires an open and available connection. the
connection's current state is closed
I have no idea why this auto generated code doesn't have a connection and I'm hungover and in no shape to deal with this. I decided to just go back to the SP's for the moment so I can get some work done. This error is still being thrown (same table adapter, same method name but reconfigured to use a SP). All of my other DB calls work fine.
I'm assuming the generated SQL code is still floating around somewhere even though I changed the adapter to use SP's. Can someone tell me where it is so I can delete it?
On another note I'm really starting to think that using SqlConnection and SqlCommand manually is a much better option, as using these query 'Tools' are just way to much trouble when it comes to flexibility such as modifying database tables etc. Can any of you more experienced people tell me if that's correct or do you advocate using table adapters?
*Edit
it also throws these:
Invalid operation. The connection is closed.
and
There is already an open DataReader associated with this Command which must be closed first.
The solution was to go to the query properties in the tableAdapter and manually change the "Command Type" to StoredProcedure.
highlight the query > go to properties window > change the command type
Seem this didn't (or doesn't) get auto updated when I reconfigure the query.
if you provide some code, it would be better.
I think, you need to open the the connection.
SqlCommand Cmd= new SqlCommand();
Cmd.Open();
// then u can use Cmd.ExecuteReader();
we have an architectual problem with our data grid. The grid supports searching, paging and sorting using a linq2entity query, that contains all of the above parameters.
At some pages, the grid should not display the content from the database (e.g. column 'name'), but the translated ressource, loaded by the Resource Provider.
Our Resource Provider gets the translations from the database and caches them to the application cache to avoid unneccessary trips to the database.
At this point, we have the following possibilities:
No searching, sorting and paging on the databse, so loading all rows, then load the translations from the Resource Provider, then do the searching, sorting and paging at the application.
Bad performance, because the database is very big
Searching, sorting and paging on the database, then load the ressources for the results.The Displayed Values will not match to the search and sort configuration
Get the Resources directly from the database, within the linq query.
The Ressource Provider Caching cannot be used. The Join with the Resource Provider Texts will be very bad and slow
Every possibility is very bad, but I can't think of another solution. Any good suggestions? How are these problems solved in other software?
You can do it by bring the associated filtered records from the database and keep it in ViewState.
How can you improve the Performance?
You can make use of JSON / Page Methods for Database Callings. I will explain it to you with the help
of an example.
Click here to check the code for GridView Bindings using JSON
Mark Up With JSON
I am calling the Code Behind methof from Client side
Code Behind
Output
Click here to check the output in case of Update Panels
Is application is holding too much memory then you need a Doctor like Red Gate Ants Memory Profiler. Click here to see more details about it
Make sure to use the Using Statements to avoid Memory Out of Exceptions
using (SqlConnection connection = new SqlConnection())
{
connection.Open();
//Also for SqlCommand... Sample code...
using (SqlCommand cmd = new SqlCommand())
{
}
using (SqlTransaction transaction = connection.BeginTransaction())
{
transaction.Commit();
}
}
Are you aware about the Teleric Grid? It loads all the records first from the database and keeps in Cache. In order to go for this you must use Paging and Disposing the objects is mandatory. Teleric Grid shows these records in Paging. Thus you can avoid the rendering issue to get rid of displaying all records in once.
i don't understand your question properly but if you want to all operations on translated resource you have to store translated resource in database then get them in to session object and apply filter on it if it is either in form of table or list then give source to grid which has to configured as work with translated resource which is filtered from session object.
In the controllers generated by Visual Studio, as well as the sample application (ContosoUniversity), the Index action always has something like
var departments = db.Departments.Include(d => d.Administrator);
What's the difference between that and
var departments = db.Departments;
First I suspected that the first one (with Include) enables the view to retrieve department.Administrator. But the second one (without Include) seems to be able to do that as well.
The Include tells Entity Framework work to eagerly load the Administrator for each Department in the results. In this case, Entity Framework can use a SQL join to grab the data from both tables in a single request.
The code will still work without the Include, but the first time you access a Department's Administrator, EF will need to hit the database to load it (since it wasn't pre-loaded). Loading data on demand (lazily) is a nice feature but it can be a serious performance problem (known as an N+1 problem). Especially if you are accessing the Administrator for each Department (for example, in a loop) - instead of one database call, you will end up with many!
In first case (with Include) when you write department.Administrator servers the object from memory that has been eagerly loaded due to Include method. In the second case, an sql statement will be executed to fetch the Administrator record from the db for each department object.
See the "Lazy, Eager, and Explicit Loading of Related Data" section in this tutorial:
http://www.asp.net/entity-framework/tutorials/reading-related-data-with-the-entity-framework-in-an-asp-net-mvc-application
var departments = db.Departments;
This will retrieves the aggregate domains only if LazyLoadingEnabled is enabled & MultipleActiveResultSets is set to true in connection string.
i'm building my web application to connect with db.
so far i have managed to deal with it, (although i didn't build BLL & DAL).
i have a table which has column "id". i know there is a way to declare it in the SQL Server to be incremented automatically. ( but i don't want it).
i want to declare a global application variable that will hold the value.
i have 2 questions:
how i declare it?
where i create it and initialize it ? (i have several login pages).
THANKS!
p.s
it would be helpful if someone will tell me how do i build the DAL with my stored procedures?
and for what i need yo use BLL which i cant do in the DAL?
You can use the Application object - it is part of the HttpContext and is directly accessible on any page.
If you don't want to use it, you may want to write a Globals class (or whatever name you like) that holds static members.
public class Globals
{
public static int Counter { get; set;}
}
// accessed from other classes:
Globals.Counter++;
Either approach will not work of you have a web farm or several web applications and will not survive restarts.
Regardless of these options, the right solution (even if you don't want to use it - can you explain why?), is to use the ID field with the IDENTITY clause.
Storing the variable is the easy part. Managing your own ID generation and the contention and concurrency issues is the hard part. Good luck.
There really is no such thing as a global variable in ASP.NET. Remember, HTTP is stateless.
The closest you can come is storing something in the Application object:
Application["myvar" ] = x;
x = Application["myvar"];
But even here, this variable is lost when the app needs to restart, which it can do from time to time.
A much better solution for what you describe is a database value.
Incrementing an integer and then throwing that incremented ID into the db is fraught with danger. Multithreading? What happens when the application bounces? Do dev and prod deployments share the same set of numbers?
It sounds like you need a globally unique identifier and can be created outside of the database. That sounds like a job for a GUID. Sure, it takes up more space in the db, but it probably isn't the worst thing you are going to do to the database.