C#•3y ago

EF Migration error

hi, I am getting an error message, and I am guessing comes from the connection string Initial catalog that I named after the name of the project from lack of info in all the sources I looked into. i followed the documentation and added App.config with a connection string and also read the page for ConfigurationManager but no one seems to tell how to name the "initial catalog" . i am following the dotNet tutorial on EF ,if anybody could help me out i really appreciate, thanks

protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
  optionsBuilder.UseSqlServer(
    ConfigurationManager.ConnectionStrings["myappnameDatabase"].ConnectionString);//line 19   
}

protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
  optionsBuilder.UseSqlServer(
    ConfigurationManager.ConnectionStrings["myappnameDatabase"].ConnectionString);//line 19   
}

App.config

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
    <connectionStrings>
        <add name="myappnameDatabase"
             connectionString="Data Source=(localdb)\MSSQLLocalDB;Initial Catalog=myappname;Integrated Security=True;" />
    </connectionStrings>
</configuration>

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
    <connectionStrings>
        <add name="myappnameDatabase"
             connectionString="Data Source=(localdb)\MSSQLLocalDB;Initial Catalog=myappname;Integrated Security=True;" />
    </connectionStrings>
</configuration>

on package console

PM> Add-Migration InitialCreate
Build started...
Build succeeded.
System.NullReferenceException: Object reference not set to an instance of an object.
   at myappname.Data.myappnameContext.OnConfiguring(DbContextOptionsBuilder optionsBuilder) (...) :line 19

PM> Add-Migration InitialCreate
Build started...
Build succeeded.
System.NullReferenceException: Object reference not set to an instance of an object.
   at myappname.Data.myappnameContext.OnConfiguring(DbContextOptionsBuilder optionsBuilder) (...) :line 19

20 Replies

Angius•3y ago

First time ever I see the connection string configured inside of some random XML file appsettings.json is usually where that config is

SalOP•3y ago

https://docs.microsoft.com/en-us/ef/core/miscellaneous/connection-strings#winforms--wpf-applications

Connection Strings - EF Core

Managing connection strings under different environments with Entity Framework Core

Angius•3y ago

Ah, a desktop project, that'd explain the XML

SalOP•3y ago

do you see any flag?

Angius•3y ago

Well, the error is about the connection string being empty. The only thing that comes to mind is either the XML file not being added to the configuration, or a name mismatch C# in general is case-sensitive, so connectionString property in that XML might be an issue Not sure

SalOP•3y ago

i didnt add the App.config anywhere (other than it being in the solution) should i add it in App resources or anywhere else? its not, i try that, the solution build is fine.... no errors

Angius•3y ago

Where is that XML you pasted if not in App.config..?

SalOP•3y ago

my solution didnt have an app.config so i added, its side by side with app.xaml i meant reference if that was not clear

Angius•3y ago

It should be in the root of your project, IIRC I'm honestly not sure

SalOP•3y ago

it is

Angius•3y ago

I never had the need to connect to a database from a desktop app

SalOP•3y ago

how would you store data?

Angius•3y ago

I generally don't make desktop apps, but I'd probably just use SQLite instead of LocalDB

SalOP•3y ago

this is kind of breaking the flow.. just needed to store values locally

Angius•3y ago

With SQLite, I wouldn't even use config, I'd just hardcode the connection string as "database.db" and call it a day

SalOP•3y ago

well that would be an option i guess, just try to learn and they say to not hard code.. but either way am i not using sqll? that name is all over

Angius•3y ago

With EF? No, you won't be writing any SQL code, you'd be using LINQ

SalOP•3y ago

well yes but the data is stored in sql i had to get the nuget for sql from ef

Angius•3y ago

SQL is a language The data would be stored in a database Whether that database is SQLIte, PostgreSQL, MariaDB, LiteDB, or SQL Server, that's another thing You probably had to get the nuget for SQL Server Since that's what LocalDB is based on

SalOP•3y ago

ok, i think is sql server actualy will try to hardcode that string to the overide it works when hardcoded. weird, before get this "closed" if anybody knows what was wrong in the app.config or ConfigurationManager please let me know, thanks @Angius thanks for your time Anybody has an idea on how to fix this issue and not hardcode the connection string? thanks

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EF Migration error