I am trying to switch different databases for a web application at Run time.
Senario
We have one asp.net web application and different databases for different customers.I am trying to switch particular connection string value from a common database where i am keeping a mapping table for connection string ,particular customer id and password .After the successful lo gin i am piking a connection string from the common database and edit the web.config file connection string section by replacing selected connection string at run time.
i am doing this by add following code to login event
conectionString = cString;
Configuration openWebConfiguration = WebConfigurationManager.OpenWebConfiguration("~");
ConnectionStringsSection sections = openWebConfiguration.GetSection("connectionStrings") as ConnectionStringsSection;
if (sections != null)
{
sections.ConnectionStrings["ConnectionStringName"].ConnectionString = conectionString;
ConfigurationManager.RefreshSection("ConnectionStringName");
openWebConfiguration.Save();
}
i am reading above connection string on a page by using ConfigurationManager.problem is the web config file is changing but after calling to another page using Response.Redirect will throw an exception .Exception is "Unable to evaluate expression because the code is optimized or a native frame is on top of the call stack "I can realized this is something happen on cross threaded environment.My questions are
What is exact reason for above exception?
which page life circle of the Asp.net reads the setting from the web config file ?
What is the proper way i can implement above scenario?
I am wondering why this question seems still unanswered.OK i have found some answermy self.It may be wrong but some how they are giving some meaning to me.I assume following are acceptable for my knowledge level.
1)I don't know the exact reason ,but this is something happen because of code is modified while an application running
2)Based on my search WEB Config file is started to read by the application when the IIS server start.So what ever values to be modified inside WEB Config ,require to restart the IIS server to load them in to memory.We can modify the connection string dynamically but still the application will run on the previous connection string.So we need t restart the IIS to load newer one.
Note:Modify a existing connection string is different than add a new connection string to a WEB Config.
3)I have used a common data Base where i have authentication details for different different connection strings for Several database.WeB config has the connection string for above master database.If an user gives his authentication detail it will select his connection string and load it as new connection string .So the remaining process will be based on that connection string.
Any new arguments for above answers are highly appreciable.I need corrections from other developers because i am very eager to learn.
Related
I have a simple data entry Windows Form with a datagridview display that links to a local database. When I run the program and try to add data on another computer, I get this message:
Unhandled exception has occurred in your application. If you click Continue, the application will ignore this error and attempt to continue. If you click Quit, the application will close immediately.
An attempt to attach an auto-named database for file C:\Users\roberto.yepez\Documents\Visual Studio\2010\Projects\Financial Aid Calculator\Financial Aid Calculator\StudentInfo1.mdf failed. A database with the same name exists, or specified file cannot be opened, or it is located on UNC share."
The file path is to the path on the computer where I coded the program.
Here is my code:
SqlConnection conn = new SqlConnection(#"Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename='C:\Users\roberto.yepez\Documents\Visual Studio 2010\Projects\Financial Aid Calculator\Financial Aid Calculator\StudentInfo1.mdf';Integrated Security=True".ToString());
I am a self-taught coder, please help! :)
I believe you're running into a problem because your local sql server to which your code is trying to attach the StudentInfo1.mdf (whose path is in the connection string) already contains a database called StudentInfo1 - it decided to try and create a database of this name based on the name of the mdf file. I'm guessing that you can pick your own name by specifying Initial Catalog in your connection string but this would mean there are two databases with possibly the same set of tables and a potential for confusion
Per the comment I posted I would instead advocate that you use SQL Server Management Studio to permanently attach your db (you make have already done this) and then adjust your connection string so that it refers to the permanently attached db. This reduces the chances that your next question will be "my code says it's updating my db but I cannot see any changes!?"
Please move this connection string
"Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename='C:\Users\roberto.yepez\Documents\Visual Studio 2010\Projects\Financial Aid Calculator\Financial Aid Calculator\StudentInfo1.mdf';Integrated Security=True"
to app.config file. When you deploy to production, change the paths in that app.config, according to the production machine settings.
You can even apply transformations on the app.config to deploy in various machines/scenarios.
I have a web form developed in ASP.NET and C#. I am storing the connection string to a database in the web.config file like this:
<connectionStrings configSource="MySecrets.config" />
This points to a local file in the same directory as the solution. Debugging locally works, however it is not advisable to commit this file to source control to avoid exposing these secrets.
This article mentions that it is possible to store connection strings on Azure - in the Configurations section of an App Service. The article also says that it's possible to retrieve the connection strings in the code by doing:
dbConn = System.Configuration.ConfigurationManager.AppSettings("myConnStringName")
The article also mentions that "if the application setting(s) happen to already exist in your web.config file, Windows Azure Web Sites will automatically override them at runtime using the values associated with your website. Connection strings work in a similar fashion.
(This assumes that your connection strings are explicit in the web.config file, and if committed to source control, they would be exposed.)
However, in my code, I already have a line with:
dbConn = WebConfigurationManager.ConnectionStrings["myConnStringName"].ConnectionString
Questions:
1) How am I supposed to reconcile these two lines without declaring the same variable (dbConn) twice?
2) How can I not commit MySecrets.config to source control, but at the same time use it when I debug my app locally, while using the connection string stored on Azure when working with the published app?
I developed a class library that uses Linq To Sql to communicate with a database.
When I added this I used Server Explorer to add a database and all the tables I want to talk to.
It then built a .dbml file for me.
In the "Designer" file I can see:
public TPDataContext() :
base(global::TPAPI.Properties.Settings.Default.TruePotentialConnectionString, mappingSource)
{
OnCreated();
}
If I update the "Linq to SQL" it regenerates a new designer.cs file
It stored the connection string in Settings.settings with the scope of "Application".
All functions just fine.
But, I have then added a winfoms project that needs to change this setting. So I added the following code:
Configuration config = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);
config.ConnectionStrings.ConnectionStrings["TPAPI.Properties.Settings.TruePotentialConnectionString"].ConnectionString = txtConnectionString.Text;
config.Save(ConfigurationSaveMode.Modified, true);
ConfigurationManager.RefreshSection("connectionStrings");
This updates the connection string in the dll but it only takes effect when the application is shutdown and restarted.
When I am upgrading clients it overwrites what the user had already entered when using it previously.
I cannot seem to work out the best way to:
Not overwrite previous user defined connection string when the app is upgraded.
Be able to save the new connection string and use it without having to stop/start the app.
Having had a read of other threads it appears that the dll shouldn't really have any "local" settings in it (?) and they should all be sent by the winforms app. But, I am unclear on how use Linq to Sql in the dll without it automatically looking/adding it's own connection string.
Can anyone help please?
Thanks
I have decided to rewrite all my DataContext calls to accept the connection string parameter.
I had to amend and test about 40 functions but now the connection string is stored in the winforms application as a user setting and overrides the default connection string generated by Linq to SQL.
So, now in my dll it now looks like
TPDataContext db = new TPDataContext(connStr);
HTH
After I deployed my mobile service to Azure, calls to the service fails because of this error:
No connection string named 'ApplicationEntities' could be found in the application config file.
The error only occurs on Azure side. When I test the service locally, the connection to the remote database works without a problem.
I separated my solution into several projects:
Web Api
Business Logic
Data Access (contains the DbContext, database first)
Common (contains the entities generated by EF)
As I always do, I copied the connection string generated in my app.config of the DataAccess Assembly into the connectionStrings-Element of my web.config (Web Api project).
<connectionStrings>
<add name="ApplicationEntities" connectionString="<the connection string>" providerName="System.Data.EntityClient" />
</connectionStrings>
In the web deploy settings, I selected the connection string for "ApplicationEntities". I tested it with and without the option "Use this connection string at runtime (update destination web.config). I always get the same error.
Then I got curious and logged the connection strings available via the ConfigurationManager with something like this:
StringBuilder sb = new StringBuilder();
for (int i = 0; i < ConfigurationManager.ConnectionStrings.Count; i++)
{
sb.AppendLine(ConfigurationManager.ConnectionStrings[i].ConnectionString);
}
trace.Info(sb.ToString());
I got two connection strings:
data source=.\SQLEXPRESS;Integrated Security=SSPI;AttachDBFilename=|DataDirectory|aspnetdb.mdf;User Instance=true
Data Source=theserver.database.windows.net;Initial Catalog=thedb_db;User ID=theuser;Password=thepassword;Asynchronous Processing=True;TrustServerCertificate=False;
The username and password is strangely different from the username and password stated in the management portal.
Also the EF-Metadata information get lost.
I get this connection strings when testing locally:
data source=.\\SQLEXPRESS;Integrated Security=SSPI;AttachDBFilename=|DataDirectory|aspnetdb.mdf;User Instance=true
metadata=res://*/DataContext.ApplicationEntities.csdl|res://*/DataContext.ApplicationEntities.ssdl|res://*/DataContext.ApplicationEntities.msl;provider=System.Data.SqlClient;provider connection string=\"data source=theserveraddress,1433;initial catalog=thedb_db;persist security info=True;user id=theusername;password=thepassword;MultipleActiveResultSets=True;Trusted_Connection=False;Encrypt=True;Connection Timeout=30;App=EntityFramework\"
I expect to get the same connection strings when running on Azure. Any idea what's going wrong?
Update:
I just went for remote debugging the service (see here). As I opened the downloaded publish-profile in my text editor, I discovered that there is an attribute SQLServerDBConnectionString - containing the connection string that always gets forced when deployed - with the same username and password I'm not aware of that it exists.
I tried to overrwite this connection string but it did not help. That connection remains the active.
Update 2 / May 29th 2014:
Seems that in the meantime the error has been fixed by the azure mobile team. Still running the same code using the database first approach and it's working now. Thanks a lot!
I have myself tried using DB first approach with dot net backend mobile services & ran into same sort of problems as you. Digging around further, following is my observation :
The azure mobile service with dot net backend must use code first approach only. This generates a specialised connection string with metadata (starting with res:)
The name of the connection string has to be the same as it is when you download the default sample todo app I.e. Ms_TableConnectionString.
There is an option in azure websites to select custom SQL provider to help make a custom connection string, this option, however, is not available for dot net backend mobile service in Azure Management portal.
P.s. Posting as answer because I don't have a enough points to comment..
Just wanted to give an update that I have been looking at this for some time and think I for the first time see it too. I don't know what is going on but wanted to let you know that we are indeed looking at it.
Henrik
(I don't have enough points to comment so having to do this as an answer)
Henrik, I have this same problem. If I ftp on to the box I can see that the web.config has the correct connection string but it fails as trying to use the username in the SQLServerDBConnectionString property (OoWUqr****Login). Is it possible you could let me know in what order it is looking for connection strings and where?
And if it can't stop it using the other user is there a way I can permission them for the correct database through mobile services?
Thanks
F
I have used app.config file for my winform application , the file is used to store the connection string which is used by all the Forms in my application to connect to a remote MySQL database.
But when I install the application on my customer's PCs, then I want that they could not see the app.config file. Is it possible? How? Please help with code.
Also, is there any other way, to create a connection string which is accessible by all the Forms. Like, can I make a class connection.cs and then inherit it in every Form.
But how to do this? I mean how to implement the code
My main objective is to create just one string for connection, so that , if i change it again and again, then i need not go and change it every Form, instead, i would just change it only in one File , and it would be used by all the Forms
Is using app.config file a good option or making a connection.cs file's a better one?
You don't need to use a connection string from every form, you need a data access layer and then you use it from everywhere, in theory only from another layer called business logic...
A form which needs to load data into a grid, a drop down or some other controls should consume data loaded by lower layers in your application stack.
Read something about 3 tier architecture.
The app.config is always visible on the user machine, so you should not treat any information stored in it as secret.
You really have two options:
Continue to store the connection string in the app.config but encrypt it. This will work fine if its an internal app and security is not to much of an issue. But since the encryption key has to be stored in the app a dedicated hacker could retrieve it.
use a three tier architecture as suggested already. With this the connection string is stored in the middle tier, while your application no longer connects directly to the database but rather through the middle tier. Authentication can then be done with a user name/password per user or by making use of windows authentication. The connection string is stored on a server and only people with acces to this server can look at it and see the DB connection string.
If you just want a simple solutions why not create a class named for example "Connection" in a file connection.cs and let it have a static attribute or property named for example "ConString" which holds the connection string:
public class Connection
{
public static ConString = "your connection string here";
}
Then you can access it everywhere:
OdbcConnection conn = new OdbcConnection(Connection.ConString);
BUT that would only be the quick and dirty way of doing it (although it works). It would be much nicer to create an own Database-Layer - but also much more work.
App.config can't be hidden on users machine, this is what you can do.
You can encrypt the connection string and store it in the app.config. have a look on this article, it shows you how to do that.
Try to define your connection string in program.cs before [statThread] by storing it in a public static string variable like constr etc. Then u can use that var anywhere referencing:
program.constr