LINQ to SQL Connection Strings with class library projects
By default, creating a new LINQ to SQL model (.dbml) will put the
connection strings in both the application settings file and also
web.config / app.config. This is not so much of a problem for web
projects, but what about class library projects? i have a connection
class where I can use it to check connection in all pages but I have an
error where it cant read DataContext at all.
This is a photo that shows my problem.
Generally speaking, class libraries don't support config files. There are ways to make it work, but it's not considered a good practice since different applications may use the same library to interact with different instances of the database. I would recommend looking at a dependency injection or inversion of control solution like Ninject to pass the connection string to the constructor from the app that references the library.
UPDATE:
If you absolutely must read a config file from an assembly instead of the calling application, it can be done with ConfigurationManager.OpenExeConfiguration(). There are several answers here on SO that provide code samples for doing so, but I'm not going to link to them because I strongly encourage you not to go down that road.
By the looks of it you're not using LINQ to SQL - all I can see is an EntityFramework edmx. Check your code generation strategy, and make sure you're trying to instantiate the correct context name (think it's whatever the Entity Container Name is set to).
Also you need to make sure System.Configuration is referenced.
You need to put the connection strings in the main application app.config
Just put a copy of the connection strings in there and you can access them or in this case web.config
Related
I'm working on my first Windows .Net application (as opposed to a .net web app, which I've done a lot of), and I have a question about database connection strings - is there an equivalent to the section in web.config?
I want to be able to have the program run against our test database (which will required a different connection string. What is the "canonical" way to define connection string objects in a Windows .Net application?
Thanks
Rather than write this all down again, here's a good article on this subject:
Storing and Retrieving Connection Strings
Add an "application configuration" file to your project. It will add a file called "app.config" Put your connection in there.
When the app is compiled it will change the name of the config file to match your executable. For example: MyApp.config.
I'm not sure what you mean by "canonical" way to define connection string objects. Name them whatever you want. Sometimes we use the name of the database, sometimes just the name of the project.
With regards to having multiple config files, we use Config Transforms. Which name them app.config, app.debug.config, app.release.config, etc. and use configuration manager to define which one to use based on where it's being deployed.
Non ASP.Net apps simply use app.config instead of web.config. See here.
Connection strings can be stored as key/value pairs in the
connectionStrings section of the configuration element of an
application configuration file.
I have a couple of web applications whose source code is missing. The project is compiled to a dll and is hosted on a IIS.
I have couple of questions to make.
What is the best way to recreate the
project from the dll file??
We are planning to change the
database server, and the database
connection strings are specified in
the Global.asax ( I mean the public
class Global : HttpApplication ). Is
there a way I can subclass this
Global and override the connection
strings? If yes, how can I make the
IIS refer to the new dll
Thank you all for any suggestions!!
For first part, use decompiler tools such as Reflector/ILSpy/dotPeek to convert IL code from DLL to higher level language such as C#. However, tools cannot get back comments, local variable names and project structure. You need to manually organize the code into files and project structures. From aspx files, you have to figure out the code-behind classes and then link up the source of the class into a correct named code-behind file - for example, if default.aspx says that it inherits from MyApp.Default then create file default.aspx.xs and put the source code for the class into that.
For second part, you can create a new class derived from Global and modify Global.asax to use that class - you need to put the assembly containing new class in bin folder and overwrite inherits clause in asax file to point to the type name of new class. You anyway need to inspect the code of your current Global class (using tools sighted above) to see if you can override connection strings by sub-classing.
Probably the best tool available to reverse engineer a dll into code is .NET Reflector. Unfortunately, the latest version is no longer free, but it is worth the money.
I am not sure exactly if this still applies if you can already reverse engineer your source code. However, I would recommend moving your connection strings outside of your project into web.config as a best practice. This way you can make the change in the future without changing any code.
Folks,
I have an ASP.NET project which is pretty n-tier, by namespace, but I need to separate into three projects: Data Layer, Middle Tier and Front End.
I am doing this because...
A) It seems the right thing to do, and
B) I am having all sorts of problems running unit tests for ASP.NET hosted assemblies.
Anyway, my question is, where do you keep your config info?
Right now, for example, my middle tier classes (which uses Linq to SQL) automatically pull their connection string information from the web.config when instantiating a new data context.
If my data layer is in another project can/should it be using the web.config for configuration info?
If so, how will a unit test, (typically in a separate assembly) provide soch configuration info?
Thank you for your time!
We keep them in a global "Settings" file which happens to be XML. This file contains all the GLOBAL settings, one of which is a connection string pointing to the appropriate server as well as username and password. Then, when my applications consume it, they put the specific catalog (database) they need in the connection string.
We have a version of the file for each operating environment (prod, dev, staging, etc). Then, with two settings -- file path (with a token representing the environment) and the environment -- I can pick up the correct settings files.
This also has the nice benefit of a 30 second failover. Simple change the server name in the settings file and restart the applications (web) and you have failed over (of course you have to restore your data if necessary).
Then when the application starts, we write the correct connection string to the web.config file (if it is different). With this, we can change a website from DEV to PROD by changing one appSettings value.
As long as there isn't too much, it's convenient to have it in the web.config. Of course, your DAL should have absolutely no clue that it comes from there.
A good option is for your data layer to be given its config information when it is called upon to do something, and it will be called upon to do something when a web call comes in. Go ahead and put the information in your web.config. In my current project, I have a static dictionary of connection strings in my data layer, which I fill out like so in a routine called from my global.asax:
CAPPData.ConnectionStrings(DatabaseName.Foo) =
ConfigurationManager.ConnectionStrings("FooConnStr").ConnectionString()
CAPPData.ConnectionStrings(DatabaseName.Bar) =
ConfigurationManager.ConnectionStrings("BarConnStr").ConnectionString()
etc.
"Injecting" it like this can be good for automated testing purposes, depending on how/if you test your DAL. For me, it's just because I didn't want to make a separate configuration file.
For testing purposes don't instantiate DataContext with default ctor. Pass connection string info to constructor.
I prefer to use IoC frameworks to inject connection to data context then inject context to other classes.
My ASP.NET application uses only 1 SQL Server 2000 database and no more than 50 tables in it. And I copied an instance of the database to run on my develop PC, so I need to switch the connections between dev and release.
The problem is, I had created multiple class libraries in my business layer, and each class library has a LINQ to SQL class. Now I find it difficult to make all of the DBML files in the different projects use the same connection string.
So is my design wrong? Should I only use 1 class library? If I continue to use multiple class libraries, how do I ensure the same connection string is used in all libraries in release mode?
Put your DBML in its own class library (assembly), and reference it in your other class libraries. That way, you can make your changes to the DBML in one place.
If you have partial classes that implement business logic, I would go ahead and put those in your other class libraries.
I'm developing a web application (ASP.NET 3.5) that will consume a number of web services. I have created a separate dll-project for each web service: these projects contains the service reference and client code.
However, the calling website MUST have the <system.serviceModel> information (the <bindings> and <client> nodes) in it's web.config, even though this information is also in the dll's app.config file! I have tried copying the serviceclass.dll.config over to the bin directory of the website, but this didn't help.
Is there any way to centralize the configuration of a WCF client?
I've only limited WCF experience, all with BasicHTTP bindings. But I'm allergic to WCF's xml files and have managed to avoid them thus far. I don't recomend this generally but I put the configuration details in my apps existing configuration store and then apply them programatically. E.g. With a Web service proxy I use the constructor for the Client that takes 'bindings'and 'endpoint' and programatically apply the settings to the bindings & endpoint.
A more elegent solution appears to be descibed here: Reading WCF Configuration from a Custom Location, but I haven't tried it yet.
From my experience, library projects never read app.config.
So you can really delete the file because it is not used. The library's host configuration is read instead, so that is the only place the endpoint and binding configuration should be.
It's possible to forgo xml config and build up the Binding and Endpoint classes associated with the service in the constructor or a custom "Service Factory". iDesign has some good information on this:
http://www.idesign.net/idesign/DesktopDefault.aspx?tabindex=5&tabid=11
(See In Proc Factory)
In their approach, you set attributes on your services to specify at a high level how they should work (ie [Internet], [Intranet], [BusinessToBusiness]), and the service factory configures the service according to best practices for each scenario. Their book describes building this sort of service:
http://www.amazon.com/Programming-WCF-Services-Juval-Lowy/dp/0596526997
If you just want to share configuration XML config, maybe use the configSource attribute to specify a path for configuration: http://weblogs.asp.net/cibrax/archive/2007/07/24/configsource-attribute-on-system-servicemodel-section.aspx
Remember that a configuration file is is read by an executable that has an entry point. A library dll does not have an entry point so it is not the assembly that will read it. The executing assembly must have a configuration file to read.
If you would like to centralize your web configs then I would suggest you look into nesting them in IIS with virtual directories. This will allow you to use the configuration inheritance to centralize whatever you need.
There are 2 options.
Option 1. Working with channels.
If you are working with channels directly, .NET 4.0 and .NET 4.5 has the ConfigurationChannelFactory. The example on MSDN looks like this:
ExeConfigurationFileMap fileMap = new ExeConfigurationFileMap();
fileMap.ExeConfigFilename = "Test.config";
Configuration newConfiguration = ConfigurationManager.OpenMappedExeConfiguration(
fileMap,
ConfigurationUserLevel.None);
ConfigurationChannelFactory<ICalculatorChannel> factory1 =
new ConfigurationChannelFactory<ICalculatorChannel>(
"endpoint1",
newConfiguration,
new EndpointAddress("http://localhost:8000/servicemodelsamples/service"));
ICalculatorChannel client1 = factory1.CreateChannel();
As pointed out by Langdon, you can use the endpoint address from the configuration file by simply passing in null, like this:
var factory1 = new ConfigurationChannelFactory<ICalculatorChannel>(
"endpoint1",
newConfiguration,
null);
ICalculatorChannel client1 = factory1.CreateChannel();
This is discussed in the MSDN documentation.
Option 2. Working with proxies.
If you're working with code-generated proxies, you can read the config file and load a ServiceModelSectionGroup. There is a bit more work involved than simply using the ConfigurationChannelFactory but at least you can continue using the generated proxy (that under the hood uses a ChannelFactory and manages the IChannelFactory for you.
Pablo Cibraro shows a nice example of this here: Getting WCF Bindings and Behaviors from any config source
First of all class libraries (DLLs) do not have their own configuration, however they can read the configuration of their host (Web/Executable etc.). That being said, I still maintain an app.config file on the library projects as a template and easy reference.
As far as the service configuration itself is concerned, WCF configuration can make somebody easily pull their hair out. It is an over-engineered over-complicated piece. The goal of your applications should be to depend least on the configuration, while maintaining flexibility of deployment scenarios your product is going to come across.