How do I create the database from the code in ASP.NET MVC 5?

Question

I am trying to learn ASP.NET MVC. I apologize in advance for my basic question.

I am having problem trying to create a database by using the model class.

Here is what I have done so far

I created a model class under "Models" folder like so

using System;
using System.Collections.Generic;
using System.Data.Entity;
using System.Linq;
using System.Web;

namespace ScripterEngine.Models
{
    public class Campaign
    {
        public int id { get; set; }
        public string name { get; set; }
        public string layout { get; set; }
        public string call_list_connection { get; set; }
        public string call_list_table_name { get; set; }
        public string status { get; set; }
        public string intro_url { get; set; }
        public string use_transfer { get; set; }
        public string route_callback_to { get; set; }
        public string call_list_database_name { get; set; }
        public DateTime created_at { get; set; }
        public DateTime modified_at { get; set; }

        //Initilize the default value
        public Campaign()
        {
            status = "Active";
            use_transfer = "No";
            route_callback_to = "Self"; 
        }

    }
}

Then I created a Campaign Context class in a new folder I created called "DataAccessLayer" like so

using ScripterEngine.Models;
using System;
using System.Collections.Generic;
using System.Data.Entity;
using System.Linq;
using System.Web;

namespace ScripterEngine.DataAccessLayer
{
    public class CampaignContext : DbContext
    {
        public DbSet<Campaign> Campaign { get; set; }

        public CampaignContext() : base("con1")
        {

        }
    }
}

Then I created an initilizer class in a new folder I created called "Seeders" to add dummy data to the table like so

using ScripterEngine.Models;
using ScripterEngine.DataAccessLayer;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

namespace ScripterEngine.Seeders
{
    public class CampaignSeeder : System.Data.Entity.DropCreateDatabaseIfModelChanges<CampaignContext>
    {

        protected override void Seed(CampaignContext context)
        {
            var campaigns = new List<Campaign>
            {
                new Campaign 
                {
                    id = 1,
                    name = "Ahold Landline",
                    layout = "topmenu",
                    call_list_table_name = "foo",
                    call_list_database_name = "bar",
                },
                new Campaign 
                {
                    id = 2,
                    name = "Ahold Cellphone",
                    layout = "topmenu",
                    call_list_table_name = "foo",
                    call_list_database_name = "bar",
                }
            };

            foreach (var campaign in campaigns)
            {
                context.Campaign.Add(campaign);
            }

            context.SaveChanges();

        }

    }
}

Finally, I added connection string and a contaxt block to my Web.config

  //I want the database table to be in the App_Data folder
  <connectionStrings>
    <add name="con1" connectionString="Data Source=(LocalDb)\v11.0;Initial Catalog=dbtest;Integrated Security=SSPI;AttachDBFilename=|DataDirectory|\dbtest.mdf" providerName="System.Data.SqlClient"/>
  </connectionStrings>

and the conext block

   <contexts>
      <context type="ScripterEngine.DataAccessLayer.CampaignContext" disableDatabaseInitialization="false">
        <databaseInitializer type="ScripterEngine.Seeders.CampaignSeeder" />
      </context>
    </contexts>

But the table does not get created? Do I need to trigger something for the table to generate? What am I doing wrong for the table not to create?

Additionally, I am trying to understand the right way of organizing my application. Is it correct to have a separate context class for every model or I should have one context class for every model? In another words, should context class represent the table or the database itself?

Thank you

you can use more than context class, but usually you don't need to, personally I've never used more than one per project — Hassan Khallouf
– Hassan Khallouf, Commented Jan 31, 2016 at 18:19
You should enable migrations for your project. asp.net/mvc/overview/getting-started/… — emre nevayeshirazi
– emre nevayeshirazi, Commented Jan 31, 2016 at 18:29

mason · Accepted Answer · 2016-01-31 18:46:36Z

4

You can use the package manage console to do commands like:

enable-migrations

add-migration Initial

update-database

This will enable migrations for code-first approach. Then create the db scripts to setup your DB based off dbcontext. Then update your DB (and run your seed) based off the migration scripts created earlier.

Link showing in more detail

edited Jan 31, 2016 at 18:46

mason

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answered Jan 31, 2016 at 18:37

mariocatch

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8 Comments

Junior Over a year ago

Thank you for the help. I want to make sure I understand what exactly to do here. In the link you provided it that I will no longer need to put the initializer class in the seeder folder like I did before rather I would jam all my seeding code into the configuration file. Did I understand this correctly? If so how can I still have one seeder per model where I can keep my code separated and clean and not jam everything into one class?

Junior Over a year ago

another thing update-database did not create the database in the App_Data the migration folder was created. Is there a way to tell the configuration class which outsides classes to include instead of jamming all my code in the configuration class.

DotNet Fan Over a year ago

and it's also recommended to do the following command before update-database: update-database -Script. And save the script to some special folder in your project. Those scripts may be useful when you need for example to restore your DB from some previous point.

mariocatch Over a year ago

Did you enable visual studio to show all files? Mdg files are hidden by default. Check the show all button at the top of the solution explorer.

mariocatch Over a year ago

Yes, the seed method can contain all of your seed logic. You can split it out if you extrapolate the logic across other seed classes. Just pass the parameter to the seed method around so you can access it.

|

Alisson Reinaldo Silva · Accepted Answer · 2016-01-31 20:47:36Z

Yep, the database will be created once you access it. So, just opening the start page of a MVC project won't create anything at all (unless you put something accessing database there).

Answering your questions, your CampaignContext or any class inheriting DbContext represents a database. For every model you could create a DbSet, like you did to Campaign, which suggests every Model represents a Table in your database, but keep in mind this is not a strict rule, depending on the architecture you use.

To make your table get generated without package manager console, you can follow the instructions below. I like to do this while I'm developing, because sometimes I like to force my database to get recreated again with fresh data, but this is up to each developer. I like to use console for installing packages, updating them, and for updating database when I do not want to drop it, because the way you did, if you change a Model, your database will get dropped and recreated, meaning you would loss any data there, though your seed method would be ran again.

Also, this is useful if you're developing to a client and you can't connect to your client's database (although in common scenarios you can do it), then you could follow the CreateDatabaseIfNotExists approach.

You could put this in your Global.asmx or Startup.cs:

 protected void Application_Start()
    {
        AreaRegistration.RegisterAllAreas();
        FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
        RouteConfig.RegisterRoutes(RouteTable.Routes);
        BundleConfig.RegisterBundles(BundleTable.Bundles);

        CampaignContext context = new CampaignContext();
        context.Database.Initialize(false);
    }

Just keep in mind your context not necessarilly will be created here, this is just an example. This is just needed if you don't want to wait until the database is accessed through another page.

Also, since I don't like keeping things in web.config, I changed your CampaignContext's constructor:

    public CampaignContext()
        : base("con1")
    {
        Database.SetInitializer<CampaignContext>(new CampaignSeeder());
    }

Therefore you can eliminate this from web.config:

   <contexts>
      <context type="ScripterEngine.DataAccessLayer.CampaignContext" disableDatabaseInitialization="false">
        <databaseInitializer type="ScripterEngine.Seeders.CampaignSeeder" />
      </context>
    </contexts>

Then add a Migrations folder in your App's root, and add a file called Configuration.cs:

internal sealed class Configuration : DbMigrationsConfiguration<ScripterEngine.DataAccessLayer.CampaignContext>
{
    public Configuration()
    {
        AutomaticMigrationsEnabled = true;
    }

}

Then run your application. Put a breakpoint in the Seed() method.

In advance, your Campaigns table will be created, but your Seed() method will fail, because your Campaign has NOT NULL datetimes and your entities you're creating without supplying a date. Since these are created and modified dates, you might want to override OnModelCreating(DbModelBuilder modelBuilder) in your context and automatically fill these data?!

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