In EF are add-migrations triggered by class changes or by the context interface?

Question

MVC5, EF 6.0 Code First, SQL

I have a remotely hosted MVC5 website using an SQL database. My objective is to easily code up to copy or copy/delete certain records out of the hosted database to a local database. So I added an additional context to my development project as shown.

Public Class WebDbContext
  Inherits DbContext

  Public Sub New()
    MyBase.New("name=WebDbConnection")
    Me.Configuration.LazyLoadingEnabled = True
  End Sub

  Public Shared Function Create() As WebDbContext
    Return New WebDbContext()
  End Function

  Public Property table1 As DbSet(Of Class1)
  .
  .
  Public Property tableN As DbSet(Of ClassN)
End Class

and in web.config I added the connection string

<configuration>
  .
  .
  <connectionStrings>
    <add name="WebDbConnection" connectionString="Data Source=<ip>;Initial Catalog=<dbname>;User ID=<id>;Password=<pwd>;" providerName="System.Data.SqlClient" />
  </connectionStrings>
  .
  .

This new context allows me to access and manipulate the website database from the development project. I will clearly need another context for the database I want to save locally, but I'm just getting started with this. I started in this direction because the Class definitions for the new context will always be up to date with the hosted database since the development project originates the Class definitions that are in the hosted database. Is there a better way to code this access to the remote database?

But my real question is: What might I expect with regard to this new WebDbContext when my next add-migration happens? Does each context create an EF add-migration requirement, or is it just the Class definitions that create the add-migration requirement and the additional context(s) won't be a problem?

Regarding access of the production database from the development project, I recognize we treat production databases differently, but this project is in early development and a quick programmatic solution is being sought. I understand at a later time when production is underway a different solution may be necessary.

Or, of course as often is the case, if there's a completely different and generally accepted way to accomplish my objective as stated at the outset, what might that be?

score 1 · Accepted Answer · answered Sep 21 '15 at 22:29

1

Not too sure if I'm fully grasping your question, but if I get the gist of your question, your trying to have 2x databases (1 localdb + 1 SQL server hosted) and want to know how to setup data migrations.

First you will need 2x connectionStrings, 1 for local and 1 for SQL

Then in your package manager console you will need to run the commands:

enable-migrations
add-migration -Name firstDbMigrationScript -ConnectionStringName firstConnnectionString
add-migration -Name secondDbMigrationScript -ConnectionStringName secondConnnectionString

Sorry if this stuff doesn't work strait up, I'm coding from memory

answered Sep 21 '15 at 22:29

Michael Crook

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Thanks. You response confirms what I've been finding out as I continued researching and is the answer. I am having trouble with update-database in the package manager console, however. If my seed tries to use data from the 'opposite' database, it doesn't find the objects. When I run the seed method from the application it finds the objects OK. Does the package manager console not allow multiple contexts as it runs? Is there a way around that? – Alan Sep 22 '15 at 00:37
first ensure that you have the solution dropdown set to the current solution, then you will have to run: Update-Database -ConfigurationTypeName MyRenamedConfiguration – Michael Crook Sep 22 '15 at 00:58

In EF are add-migrations triggered by class changes or by the context interface?

1 Answers1