I have a library that I have created that depends on EF Codefirst for DB interaction. I am also using EntityMigrations Alpha 3. When I use the library in my main application (WPF) everything works fine and as expected. Another part of the system uses Excel and retrieves information using the same library via an additional COM class in between.
In the Excel scenario, as soon as it tries to connect to the database, it throws up an exception to do with "The Provider did not return a ProviderManifestToken".
I'm really not sure why I'm only getting the error when I go through Excel/COM. In both scenarios I can confirm that the same DB connection string is being used. THe method to retrieve the DB Connection string is also the same - they use a shared config file & loader class.
Any suggestions welcome.
Issue resolved.
I had also created a custom DBIntializer and part of the intialization calls upon EntityMigrations to ensure the DB is up to date. The custom migration calls the default constructor on your context. By convention this will either dynamically use it's own connection string for SQLExpress(I don't have installed) or try to look for an entry in your config file (I don't have this either for the dll - config comes from hosting apps).
This is what is causing the failure when being used from Excel(In my scenario). The Migration will be newing up an instance of the context using the default constructor. This means that a config entry for the connection string is required or it uses the default process(SQLExpress). When being used from Excel in a COM env – no config file exists.
Moving the migration out of the Initialization strategy means I no longer have a problem.
Related
I have been developing Standard Logic Apps with SQL Server successfully for some time, but suddenly can no longer connect. I'm using Azure AD Integrated as my Authentication Type, which I know is OK as I use the same credentials in SSMS. If I try to create a new credential, it is apparently successful but on save the Logic App says "The API connection reference XXX is missing or not valid". Something has changed, but I don't know what ... help!
per above, this was submitted to M/S and has been resolved as follows: the root cause is if a Logic App Parameter name includes an embedded space the problem with SQL connections is triggered. This is a pernicious problem, as the error message is quite unrelated to the root cause. Further, since embedded spaces are supported in Logic Apps e.g. in Step Names, it is easy to assume the same applies across the board.
I have this SpringBoot server app using PostgreSQL database if it's up and sending error response if it's down. So my app is running regardless the database connection.
I would very much like to test it (jUnit / mockmvc).
My question is very simple, yet I did not find the answer online:
how does one simulate a database connection loss in SpringBoot?
If anyone wants, I can supply code (project is up at https://github.com/k-wasilewski/workshop/)
Have you thought of Testcontainers? You can spin up your docker image through a Junit test and make your spring boot use that as your database.
Since you use junit, you can start/stop this container at will.
This will generate a test which creates the condition you are looking for and write code as to what to expect when the database is down.
Here are some links to get started,
Testcontainers and Junit4 with Testcontainers quickstart - https://www.testcontainers.org/quickstart/junit_4_quickstart/
Spring boot documentation - Use Testcontainers for integration testing
https://docs.spring.io/spring-boot/docs/current/reference/htmlsingle/#howto-testcontainers
Testcontainer github link example for springboot app
https://github.com/testcontainers/testcontainers-java/tree/master/examples/spring-boot
Testcontainer - Generic container javadoc. You can find methods for start/stop
container here. call from your Junit.
https://javadoc.io/static/org.testcontainers/testcontainers/1.12.4/org/testcontainers/containers/GenericContainer.html
You can implement your own Datasource based on DelegatingDataSource and then let it throw exceptions instead of delegating when ever you want to.
I've done this before by creating a Spring Boot test configuration class that created the DataSource and wrapped it in a Java proxy. The proxy simply passed method calls down to the underlying DataSource, until a certain flag was set. Once the flag was set, then any method called on the proxy would throw an exception without calling the underlying DataSource. Essentially, this allowed me to "bring the database down" or "up" simply by flipping the flag.
I am coding a MVC 5 internet application, and am wishing to use Hangfire for recurring tasks.
How can I setup Hangfire to use SQL Server storage without specifying this in the Startup.Auth ConfigureAuth(IAppBuilder app) function.
Here is a resource link for SQL Server configuration: http://docs.hangfire.io/en/latest/configuration/using-sql-server.html
This resource states that:
If you want to use Hangfire outside of web application, where OWIN
Startup class is not applicable, create an instance of the
SqlServerStorage manually and pass it to the JobStorage.Current static
property. Parameters are the same.
The example code is as follows:
JobStorage.Current = new SqlServerStorage("connection string or its name");
I have tried the following code (with my own connection string), yet the dashboard is not available. I have called the code above from a controller function.
Is there something that I have not done correct? How can I setup Hangfire to use SQL Server storage without using the Startup.Auth class?
Thanks in advance.
I think this is your problem:
I have called the code above from a controller function.
You should be setting this up once on application startup - either in the Configuration method of an OWIN Startup class (followed by an app.UseHangFireServer();), or in the Application_Start method of your Global.asax.cs if you really don't want to use OWIN. Either way, the line you're looking for is right there in the documentation you reference:
Hangfire.GlobalConfiguration.Configuration.UseSqlServerStorage(#"connection string or connection string name");
HOWEVER, as far as I know, if you want to use the dashboard you must configure that part via OWIN along with an authorization filter. See http://docs.hangfire.io/en/latest/configuration/using-dashboard.html
So really, I don't know if any downside of using the OWIN configuration for all of this. It's the more modern platform, and since you mention this is for an MVC5 app it's unlikely that you have legacy concerns.
I am trying to allow users to type in the data source into a dialog which I am then writing to the app.config for the application. The scenario I am having a problem with works like this:
1) User types the data source into my dialog and the dialog adds or updates the connection string. In this scenario the user typed the wrong data source the first time.
2) The user then opens the dialog that has the EF code (which inits the connection string stuff) and EF throws an exception that it cannot connect.
3) The user goes back into the original dialog and puts the correct data source name in and the app.config is again updated.
4) The user the opens again the dialog that triggers the EF code and EF still has the old data source in there although it is correct now in the app.config.
I have tried
ConfigurationManager.RefreshSection("connectionStrings").
I have tried running
MyEFContainer.Database.Initialize() as well.
Neither seems to work. What do I need to do to have EF refresh the connection string data without forcing the user to close and reopen the app? If they do that then it works.
I would always work with a connection string in memory. Keep it e.g. in a context factory. Initially you read it from the config file, but it may get replaced by a new one. You store the new one in the app.config (when it is valid) for the next run of the application.
Are you instantiating a new instance of the DbContext class after the connection string is corrected? Reusing the DbContext instance that initially failed would be the problem.
For the moment,I think to force EF to reload app.config .After we change the app.config the
ConfigurationManager.RefreshSection("xxx")
is not worked for EF,so you must to restart your application.
The best way to solve the problem:
with NO Connection strings in app.config.
Uses automatic migrations and 2 databases using the same context. The real runtime supplied Connection. Approach.
I want to make database queries in my Jersey REST webapp. The ideal situation would be to find a way where the database connection is initialised once at the first app run. Afterwards I only get the instance of DAOFactory object in my REST class and make the queries in the methods. I am using mysql connector. Is there a way to find a way to do it in Jersey? In JSF it was possible - I just used an application-scoped bean when I run the code. Moreover it would be good if I could access the ServletContext object inside this method cause I would like to use it's getResourceAsStream() method to read the database connection parameters from WEB-INF/dao.properties file. But the 'only once per app initialisation' is the crucial part here.