Blazor with Database First - entity-framework-core

I'm trying to build a simple CRUD app using Blazor in Visual Studio 2019 - I have watched over 7 tutorials between YouTube, PluralSight, and Channel 9, and in all of them, they use Entity Framework Core to create the Database and Tables from within Visual Studio, which is understandable as code-first is ideal architecture.
However my database and tables already exist, and for the first step, I just want to connect the Blazor app to a table and read it into UI columns.
How would I accomplish the step of importing an existing database table in Visual Studio 2019? If there is documentation on the web that refers specifically to accomplishing this in Blazor, please do point me to that, as I'm not able to find anything outside of some old ASP.Net MVC docs.

Add the following Packages to your project:
<PackageReference Include="Microsoft.AspNetCore.Diagnostics.EntityFrameworkCore" Version="3.1.1" />
<PackageReference Include="Microsoft.AspNetCore.Identity.EntityFrameworkCore" Version="3.1.1" />
<PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer" Version="3.1.1" />
<PackageReference Include="Microsoft.EntityFrameworkCore.Tools" Version="3.1.1">
Add your database connection string to appsettings.json
{
"ConnectionStrings": {
"MyConnection": "Server=tcp:<yourServer>,1433;Initial Catalog=<yourDatabase>;Persist Security Info=False;User ID=<yourDatabaseUserName>;Password=<yourDatabaseUserPassword>;MultipleActiveResultSets=False;Encrypt=True;TrustServerCertificate=True;Connection Timeout=30;"
}
}
Open PackageManagerConsole and type
Scaffold-DbContext -Connection name=MyConnection -Provider Microsoft.EntityFrameworkCore.SqlServer -OutputDir Models -Context MyDbContext -Force
This will create a Models folder in your project containing MyDbContext.cs plus a
<TableName>.cs-file for each table in your database.
Note: For the first import of your database you don't need the -Force option in the Scaffolding. It will be needed though, if you make changes in your database after the first import and want to update your cs-classes afterwards.

In our company we are using EF Core Power Tools for generating the context and the model classes for Entity Framework Core.
You can find the corresponding documentation under https://github.com/ErikEJ/EFCorePowerTools/wiki/Reverse-Engineering. With this tool you can directly generate the classes within Visual Studio and you also can store the configuration that you easily can update your classes if the database changes.

Rene's answer is correct it just needs 2 amendments:
You need to add a / before the > on the last package reference.
You will also need to reference "Microsoft.EntityFrameworkCore.Design" Version="3.1.1"

Related

query a db function using ef core?

does anybody know if it’s possible to query an sql server with my own query?
I can't find any information, that I can get to work, so perhaps there is something else I'm missing?
I have tried a LOT of samples from different websites, so it's for the lack of trying
(I'm new to ef (and ef core))
I would like to write a sql to call a database function that for some reason is not part of the database scaffolding
I have added the following nuget packages (I don’t think I’m missing any?)
PackageReference Include="Microsoft.EntityFrameworkCore" Version="6.0.6" />
PackageReference Include="Microsoft.EntityFrameworkCore.Abstractions" Version="6.0.6" />
PackageReference Include="Microsoft.EntityFrameworkCore.Analyzers" Version="6.0.6" />
PackageReference Include="Microsoft.EntityFrameworkCore.Design" Version="6.0.6">
PackageReference Include="Microsoft.EntityFrameworkCore.Relational" Version="6.0.6" />
PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer" Version="6.0.6" />
PackageReference Include="Microsoft.EntityFrameworkCore.Tools" Version="6.0.6">
I have run dotnet tool install --global dotnet-ef
(Hours spend on scaffolding not working, before I ran that command)
I used the following to scaffold
dotnet ef dbcontext scaffold "Data Source=myservername;Initial Catalog=mydbname; Persist Security Info=True;User ID=myuserid;Password='mypassword'" Microsoft.EntityFrameworkCore.SqlServer --output-dir Models
It generates fine into models folder
But who do I write a "raw" query, so I can use the db function?
This document describes how to configure EF to talk directly to a UDF.
See the section "Mapping a method to a SQL function"

EF Core Scaffolding DB results in two classes for some tables

I needed to scaffold the database tables of my database to my project so as usual, I ran:
Scaffold-DbContext "User ID=xxx;Password=xxx;Host=localhost;Port=5432;Database=xxx;" Npgsql.EntityFrameworkCore.PostgreSQL -OutputDir Database -f
But realised I was getting two classes for a couple of tables.
I have a table called Building and another called Appartment but the scaffold command created Building.cs, Building1.cs, Appartment.cs, Appartment1.cs.
The other tables were fine.
The only references to these tables are the ones within OnModelCreating in addition to other tables which have a FK to Building and Apartment. Fk's seem to not be present on the main classes (the ones without 1 appended).
I am using version 3.1.4:
<PackageReference Include="Microsoft.EntityFrameworkCore.Tools" Version="3.1.4" />
<PackageReference Include="Microsoft.EntityFrameworkCore.Design" Version="3.1.4">
Has anyone seen this before?
I added audit tables for both of the tables in question under a different namespace. Completely forgot about them.

Database first create entity framework 6.1.1 model using system.data.sqlite 1.0.93

I have a project that I just updated using nuget. This updated entity framework from 6.1 to 6.1.1, and it updated sqlite to 1.0.93. I wanted to update my model from my latest database. I did the steps of
1) Model from Database
2) Select sqlite database
3) Generate
After the generation I received the following error message shown below. I have the 1.0.93 design time components install. Does anyone know what exactly is causing this error. The project references and versions all match the versions shown above.
Error Message:
Your project references the latest Entity Framework; however and Entity Framework database provider
compatible with this version could not be found for you data connection.
Update:
I ended up installing 6.1.0 manually using the package manager console
Install-Package EntityFramework -Version 6.1.0
Then in my csporj files replacing
packages\EntityFramework.6.1.1
with
packages\EntityFramework.6.1.0
I tried creating EF Designer from Database and Code First from Database but I am still getting the same error.
UPDATE
I have followed the instructions Tom has provided, and thanks time for taking the time to respond in depth it is appreciated. But I cannot get the entity framework designer to work with SQLite 1.0.93. What I have found:
1) When I add the SQLite data source from the tools menu as Tom describes I see the SQLite data provider.
2) But when I restart visual studio the data source is not connected
3) The data source can be refreshed and it is valid after restart
4) Add new data item but SQLite is not listed as a provider
I have double checked the registry and EF6 is appended to the invariant name, the SQLite dlls are registered in the GAC. I will try to see what else I can find but at this point I am not sure what to look for. As a side note I have tried dotConnect and it does not work either with EF 6.1.1.
Update 2
Does anyone know if the Entity Framework Designer has a logging option to find out what might be happening?
[ UPDATE : for an easier solution that works with Visual Studio 2013 Update 4 (Pro and Ultimate) and recent versions of Sqlite Providers and EF, look at the solution 'broslav' posted below. Don't know if it works with Express editions... ]
Ok, this is a suggestion. This does NOT work for Visual Studio Express editions.
Also, I'm not sure how to get it to work for an update of an existing project.
And it is an absolute pain in the butt.
I haven't tested if everything is required, but this should work:
First, do NOT use the NuGet package for SQLite, but download the assembly installer from here:
http://system.data.sqlite.org/index.html/doc/trunk/www/downloads.wiki
Install the Setups for 32-bit Windows (.NET Framework 4.5.1) installer: sqlite-netFx451-setup-bundle-x86-2013-1.0.93.0.exe (10.00 MiB) (NOT the 64-bit version). This is the only one with the designer.
Install and select to install in the GAC and install the Designer for VS13.
For the following, the exact order is important!
I made a video of these steps, see: http://vimeo.com/103372740
Create a project in VS13. Target the build to framework 4.5.1 and x86 explicitly. Save and build.
Next, install the latest EF 6 package (6.1.1) from NuGet. Save and build.
Manually add references to the installed SQLite assemblies (including the Designer) , under the Reference Manager under Assemblies you can find the Extensions option for selecting the four added assemblies in the GAC : System.Data.SQLite Core + Designer + for Entity Framework + for LINQ.. Save and build.
Then create a connection to your database via Connect to Database under Tools. Before you do anything else Save and Build and then RESTART Visual Studio. DO NOT DO ANYTHING ELSE before starting the ADO.NET Entity Data Model wizard, so DO NOT refresh the database connection.
Add an ADO.NET Entity Data Model, select Generate from Database.
Your database connection will show up in the drop-down list. Keep it there, but select to create a New Connection anyway and select the exact same database again (as if you are creating a new connection). It sounds silly, but it is crucial, see image below...
When I actually Added an ADO.NET Entity Data Model this way it did present the annoying error, but the Next button is selectable and everything worked regardless (amazingly)!
Designer works, retrieving data and writing data works.
Haven't tested deployment on another machine though... I'm using Win7 64-bit.
CHANGED UPDATE: To get the correct configuration to actually access the database, you have to install the System.Data.SQLite.EF6 package from NuGet after doing all of the above, then add
<provider invariantName="System.Data.SQLite" type="System.Data.SQLite.EF6.SQLiteProviderServices, System.Data.SQLite.EF6" />
to the App.Config and remove the other providers and remove everything in between <system.data></system.data>, otherwise you'll get some exception. But note that this means that every time you want to update the EDMX model, you have to change the App.Config invariantName="System.Data.SQLite" to invariantName="System.Data.SQLite.EF6" and vice versa.
** Is this getting ridiculous? Yes, it is! And it gave me quite a headache... **
This is what worked for me:
had Windows 8.1 Pro x64
had VisualStudio 2013 Ultimate Update 4
installed http://system.data.sqlite.org/downloads/1.0.94.0/sqlite-netFx451-setup-bundle-x86-2013-1.0.94.0.exe (in GAC, plus designer)
installed EFTools6.1.2ForVS2013.msi from https://www.microsoft.com/en-us/download/details.aspx?id=40762
in old or new solution/project that targets .NET 4.5.1 and Any CPU installed via NuGet package System.Data.SQLite
added new model from database (I did not see the SQLite provider here until I installed the NuGet package inside the project)
to actually access the data, I had to rearrange the add and remove items inside the DbProviderFactories tag in the app.config
So the packages I had were:
<packages>
<package id="EntityFramework" version="6.1.1" targetFramework="net451" />
<package id="System.Data.SQLite" version="1.0.94.1" targetFramework="net451" />
<package id="System.Data.SQLite.Core" version="1.0.94.0" targetFramework="net451" />
<package id="System.Data.SQLite.EF6" version="1.0.94.0" targetFramework="net451" />
<package id="System.Data.SQLite.Linq" version="1.0.94.1" targetFramework="net451" />
</packages>
and the app.config that worked for me had contents:
<?xml version="1.0" encoding="utf-8"?>
<configuration>
<configSections>
<!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 -->
<section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" />
</configSections>
<entityFramework>
<defaultConnectionFactory type="System.Data.Entity.Infrastructure.LocalDbConnectionFactory, EntityFramework">
<parameters>
<parameter value="mssqllocaldb" />
</parameters>
</defaultConnectionFactory>
<providers>
<provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />
<provider invariantName="System.Data.SQLite.EF6" type="System.Data.SQLite.EF6.SQLiteProviderServices, System.Data.SQLite.EF6" />
</providers>
</entityFramework>
<system.diagnostics>
<sources>
<!-- This section defines the logging configuration for My.Application.Log -->
<source name="DefaultSource" switchName="DefaultSwitch">
<listeners>
<add name="FileLog" />
<!-- Uncomment the below section to write to the Application Event Log -->
<!--<add name="EventLog"/>-->
</listeners>
</source>
</sources>
<switches>
<add name="DefaultSwitch" value="Information" />
</switches>
<sharedListeners>
<add name="FileLog" type="Microsoft.VisualBasic.Logging.FileLogTraceListener, Microsoft.VisualBasic, Version=8.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL" initializeData="FileLogWriter" />
<!-- Uncomment the below section and replace APPLICATION_NAME with the name of your application to write to the Application Event Log -->
<!--<add name="EventLog" type="System.Diagnostics.EventLogTraceListener" initializeData="APPLICATION_NAME"/> -->
</sharedListeners>
</system.diagnostics>
<startup>
<supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5.1" />
</startup>
<system.data>
<!--
NOTE: The extra "remove" element below is to prevent the design-time
support components within EF6 from selecting the legacy ADO.NET
provider for SQLite (i.e. the one without any EF6 support). It
appears to only consider the first ADO.NET provider in the list
within the resulting "app.config" or "web.config" file.
-->
<DbProviderFactories>
<remove invariant="System.Data.SQLite" />
<add name="SQLite Data Provider" invariant="System.Data.SQLite" description=".NET Framework Data Provider for SQLite" type="System.Data.SQLite.SQLiteFactory, System.Data.SQLite" />
<remove invariant="System.Data.SQLite.EF6" />
<add name="SQLite Data Provider (Entity Framework 6)" invariant="System.Data.SQLite.EF6" description=".NET Framework Data Provider for SQLite (Entity Framework 6)" type="System.Data.SQLite.EF6.SQLiteProviderFactory, System.Data.SQLite.EF6" />
</DbProviderFactories>
</system.data>
<connectionStrings>
<add name="WorkinDataEntities" connectionString="metadata=res://*/WorkinDataModel.csdl|res://*/WorkinDataModel.ssdl|res://*/WorkinDataModel.msl;provider=System.Data.SQLite.EF6;provider connection string="data source=X:\dev\proj\workin\bin\data.db"" providerName="System.Data.EntityClient" />
</connectionStrings>
</configuration>
As you can see, somehow in the end, for me, it was not necessary to remove "EF6" from invariantName or to remove or rearrange other providers or default connection factories. I didn't have to do any reg hacks. Rearranging add/remove tags (that were added during NuGet System.Data.SQLite 1.0.94.1 package installation) in the start-up project's app.config made the difference.
After all the above, I updated EntityFramework to 6.1.2 via NuGet and both updating the model from database via designer and accessing the data at runtime still works.
I finally have steps to consistently add Sqlite and EF6 to a project:
EF6: versions 6.0.0 to be 6.1.3 (currently the latest version).
System.Data.Sqlite: 1.0.93 - 1.0.95 but not 1.0.98 (currently the latest version).
To avoid getting System.Data.Sqlite 1.0.98 , do not install using Nuget Package manager. Manually install System.Data.Sqlite. Unfortunately, http://system.data.sqlite.org/ does not readily list previous downloads.
x86 System.Data.Sqlite 1.093
x64 System.Data.Sqlite 1.093
I use Nuget Package manager and install EF6 and then I manually added System.Data.Sqlite library. I have tried multiple times to use 1.0.98 but I cannot
App.config File
For my implementation, I am working with database first an manually coding the entity data classes
public partial class MyDbContextEF : DbContext
{
public MyDbContext() : base("name=MyDbContext") { }
public DbSet<DataRecord> DataRecords { get; set; }
}
[Table("TableName")]
public class DataRecord
{
[Key]
public Int64 RowID { get; set; }
public string Name { get; set; }
}
I reported this issue and a fix is under way, and a workaround appears to be available (I have not tested it) http://system.data.sqlite.org/index.html/tktview?name=e634e330a6
I had the exact same problem--The model designer wizard was not showing my sqlite db in the dropdown list. I was able to resolve it by fiddling with the sqlite db connection and tables.
0a) I added a connection through the Server Explorer to my sqlite file (the sqlite providers and servers showed in new connection wizard for the Server Explorer but not my edmx Model Wizard)
0b) At this point it was not showing in the edmx Model Wizard still, but did show as a Data Connection in the Server Explorer.
1) I added a table to the sqlite file.
2) I closed the connection to the sqlite db through the Server Explorer
3) I opened the design of my dummy table om the sqlite file through the Server Explorer (thus reinitiating the connection)
4) I tried to "Update Model from Database..." and it was showing in the dropdown list
Another step I did not include above was I created and deleted an .mdf SQL server database New Item... > Database Service.... I did that shortly before trying the above steps. I assume that wouldn't matter but you never know.
Not sure what exactly did it. It seemed a manual disconnect and reconnect through the server explorer made VS "wake up" and display the server in the list. Try fiddling with the connection and tables a bit to see if that wakes something up.
I had this problem as well. The cause was probably that I forgot to tick the visual studio checkbox when installing the system.data.sqlite driver and then installed over that with the checkbox ticked without deinstalling the system.data.sqlite driver first. This how I solved it:
Uninstall the system.data.sqlite driver.
Reboot.
Install the system.data.sqlite driver
Delete the old solution and set it up anew, just like you did (might not be necessary).
Add the ADO.NET entity model (the template was missing for me, this answer helped with that)
The sqlite data source should now be available.

Publish Web dialog doesn't detect my entity framework 5 context as Code First

I've recently upgraded a WFC project that uses Entity Framework from v4.3.1 to 5.0.
I'm running Coded migrations only (no automatic migrations).
Previously, I was using the Publish Profiles to deploy this solution and apply the migrations. Since upgrading the project to EF5, the migrations portion no longer works and the publish dialog doesn't detect the context as having code-first migrations.
Specifically, the .pubxmlfile changed from detecting my context as <Object Type="DbCodeFirst">to <Object type="DbDacFx"> which is incorrect for my context.
As a workaround, I've manually added the <entityFramework> database initializer configuration to my web.config transforms, but I'd like to understand why the publish profiles aren't working. That was a much nicer solution.
It once happened on me when merging another developer's commit and triggered Visual Studio project reload. That's how it caused the "DbCodeFirst" to "DbDacFx" change.
If I restart Visual Studio then everything goes back to what it should be.
Just another thought.
You probably missed adding the reference to EntityFramework into your project. By just adding the reference you should be able to control whether or not the DbCodeFirst option is available or not.
As this post suggests, try using the fully-qualified name of your DbContext as the name of the connection string. Instead of:
Web.config
<connectionStrings>
<add name="MyContext" .../>
</connectionStrings>
Use:
Web.config
<connectionStrings>
<add name="MyNamespace.AnotherNamespace.MyContext" .../>
</connectionStrings>
In my case, in order to use my existing publish profiles (.pubxml), I also had to manually edit the <ObjectGroup Name="..." ...>. Probably recreating the publish profiles would work too.
I had the same issue but not in the same context.
I had been using Code First Migrations with existing ASP.NET MVC 5.2.3 application using EF 6.1.3 for a month without issues. At one point in time I added support for Windows Azure Storage but I made some mistakes:
I added a new project. Unfortunately I chose "Console Application" instead of "Class Library". I tried to fix it by changing it back to "Class Library" in "Project Settings"
I used Nuget to Install-Package WindowsAzure.Storage but I installed it on the MVC project and not on the class library. I tried to fix it by doing Uninstall-Package on the MVC project and installing it to the correct project
I called the class in the class library "WorkOrderStorage"
I added the connectionString to <connectionStrings> element in web.config and a transformation in web.release.config
I guess my project was now in an inconsistent state. I noticed that it would forget about Code First Migrations (I monitored the changes to the .pubxml file):
when I put a reference between the MVC project and the library
containing the WorkOrderStorage class
when I created an empty 'WorkOrderStorage' class in one of the existing libraries
In the end I fixed it by recreating this library correctly from scratch as a class library (because of observation 1). I also named the class WorkOrderRepository (because of observation 2).

Entity Framework Code First Data Migrations not working with VS2012 Web Deploy

I have created an MVC 3.0 application using Visual Studio 2012, .NET 4.5 and Entity Framework 5.0.
Using Code First Data Migrations, I am able to correctly propagate model changes to my local test database, but I can't figure out how to get this to work when deploying to my staging and production servers using Web Deploy.
I have read the following article ...
http://msdn.microsoft.com/en-us/library/dd394698(v=vs.110)#dbdacfx
... which explains what's supposed to happen, but it's not working for me, as Web Deploy seems unable to detect that I am using Entity Framework. The tutorial shows a checkbox to enable execution of Code First Migrations ...
... but my dialog shows the only Update Database checkbox for each database.
I have read that, in order for Visual Studio to detect the use of an Entity Framework context, the Web.config must include an element that defines it. Here's mine:
<entityFramework>
<defaultConnectionFactory type="System.Data.Entity.Infrastructure.SqlConnectionFactory, EntityFramework" />
<contexts>
<context type="MyContext, MyAssembly">
<databaseInitializer type="System.Data.Entity.MigrateDatabaseToLatestVersion`2[[MyContext, MyAssembly], [MyConfig, MyAssembly]], EntityFramework">
<parameters>
<parameter value="MyConnectionStringName"/>
</parameters>
</databaseInitializer>
</context>
</contexts>
</entityFramework>
Any suggestions would be greatly appreciated.
Thanks,
Tim
I have discovered the solution to this problem through experimentation.
In fact, my MVC application was created by VS2012 by converting from a VS2010 solution. Since the conversion process did not report any issues, I assumed that it had correctly converted everything, including the publishing profiles.
However, I discovered that the problem was in the conversion of these profiles and, unless I manually edit their XML files, there is apparently no way to get old imported profiles to participate in Code First Migrations.
Simply creating new publishing profiles in the converted solution results in the expected behavior.
Try this:
Enable-Migrations -Force
Ensure the below is set to true
AutomaticMigrationsEnabled = true;
Republish - worked for me