Is it possible to get the sql that will be executed for an update statement from an EF 4 ObjectContext? I know how to get it from a query but not from an update/insert statement....
No, not directly. You can use SQL Server Profiler, a third party profiler, and or a tracing provider.
Related
I have a ASP.NET Web application. The application connects three different databases. So I have defined three connection string in web.config with different database name and credentials.From the application code I am pointing to the relevant connection string and firing stored procedures. Sometimes the procedures are hitting the wrong database. My guess is that as .NET cache the web.config, somehow the framework is returning the wrong connection string from cache and the application hitting the wrong database. I have checked the application code and found it is pointing to the correct connection database in all cases. Is this happening due to web.config chancing? I cannot identify the root cause of the problem. Please help.
If you are using EF to connect to the database, you have to close the scope of the context and then initialize a new context with the required connection string and then use that context to execute the SP.
I don't think this is an issue with the caching !
If there is only one DAL which connecting to different databases then it is a high chance of application mistake somewhere.
Possible solution, as we have no idea of how is you data access code looks like, is to create 3 different DAL and in each of them realize logic to work only with specified connection string.
For example create 3 different classes inherited from DbContext with different connection strings in constructors.
Validation can happen on client side and server side, what if it happens on db side, if I want to stop an insert/update by rollback in trigger, how do I notify the client side, now it seems breezejs just ignore my error raised in trigger.
If you are using an Entity Framework or NHibernate backed server, then throwing any exception on the server should fail the entire transaction and turn into a failed save on the client ( with all changes placed back into their 'presave' state). In order for this to occur the Breeze server must detect an exception. You may need to have your trigger to raise an exception.
If you are using some other server, the behavior depends on whether the database supports tranactional semantics. ( for example MongoDB does not).
Found it does return, just need set severity to higher and parse error message from http data.
I have an ASP.NET MVC application that uses NHibernate to persist data into a SQL Server database.
There are cases where I want to save an entry into a database (initially triggered by a call into an action method on a controller) but there's no need to block the caller.
Is it "safe" to try to implement a fire-and-forget mechanism into the database that will put the database call into a Task and then invoke it on the background so control can return immediately to the caller? (OR accomplish the same thing with BackgroundWorker or the "async/await" keywords) I need a solution where NHibernate will not get tripped up by ASP.NET trying to clean up its ISession, which is per-request. I'm using Autofac for lifetime management on the session. I assume that the database operation would have a slightly longer lifetime than the web request itself, and I'm not sure how smoothly that would work.
It is not safe to do this; I have a blog post on the subject. The problem is that when you have no requests in progress, it is possible that your entire AppDomain can be torn down. Also, consider what would happen if the database insert failed for some reason? If you return early, then there's no way to notify the client of an error.
A reliable solution must store the data in some kind of persistent place before returning success to the caller. This can be directly in the database, or in a queue of some kind (to be later processed by an independent worker).
I developed an Client/Server data base application, using Firebird IBdatabase, IBquery. I need to know how to refresh the data on the server AND client when one of them has update/insert query. The reason being that when I run a query on the client, after I inserted records into a table, the new records do not reflect in the queries. Until i disconnected and reconnect again
I'm using a Firebird DB with InterBase VCL, developing in Delphi XE2
You don't have to disconnect the connection, but you will have to refresh (or close and reopen) the IBQuery. This is the case for most databases.
If you do not want this, you will have to send a notification from the database to all clients. I don't know if this would be doable from FireBird, but it is not common at all for databases to do this.
The transaction type for your select query is probably snapshot. You can either start a new snapshot transaction each time you want to refresh, or use transaction type read committed.
I'm using grails but I have lot's of stored procedures I'm trying to call from groovy.Sql.newInstance...
In all the examples I've found I never see anyone actually calling close on the connection. But when I tried running a bunch of methods within one response that each uses its own call to newInstance, then it got an error that there were too many connections. That leads me to believe that it isn't pooling the connections. That's a bummer. So do people create one connection and pass it around? Does grails and groovy close the connection at the end of the request?
I don't think that the connection is automatically closed after a request (which wouldn't be cool either), but you can manually close the connection used by the Sql instance:
Sql sql = Sql.newInstance("jdbc://...")
// some queries
sql.close()
See the JavaDoc.
If you would like to use pooled connections (which is surely a good idea), you should be able to create a pooled BasicDataSource (as Spring bean) and use the Sql(DataSource dataSource) constructor of Sql, rather than newInstance().