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    <p>This is my attempt at <code>Db Initializer</code> which combines both <code>Migration</code> initializer and the default <code>Db Create</code> one with seeding. (note: it's not ideal, more like a simple exercise but gives a solution to what you're asking here, mostly works - just check all the updates I made). </p> <blockquote> <p><a href="https://stackoverflow.com/questions/15796115/how-to-create-initializer-to-create-and-migrate-mysql-database/15796416#15796416">How to create initializer to create and migrate mysql database?</a></p> </blockquote> <p>As for the <code>why</code> and <code>how</code> - to fully understand that I'd suggest you also consult the <a href="http://entityframework.codeplex.com/" rel="nofollow noreferrer">EF source code</a> (that's new version but in many ways similar) </p> <h3>1)</h3> <p><strong>a) Db initializer gets called usually only once</strong> (per connection) - and when you try to access your 'model' for the first time (first query or similar). Put a breakpoint in your initializer to check. </p> <p>So it's completely safe to put it within constructor (though I prefer it on startup somewhere, config also). <strong>It only gets called when it's needed to initialize</strong> (and the <code>last one set</code> is used), you shouldn't invoke it manually. </p> <p>Anyhow, to force the initializer you can do the <code>this.Database.Initialize(force: true);</code> </p> <blockquote> <p>For when switching connections see my post on problems<br> <a href="https://stackoverflow.com/questions/15926897/code-first-custom-connection-string-and-migrations-without-using-idbcontextfacto/15938194#15938194">Code first custom connection string and migrations without using IDbContextFactory</a></p> </blockquote> <p><strong>b)</strong> If you create your own <code>IDatabaseInitializer</code> and you still want migrations to work <code>side by side</code> </p> <p><strong>You shouldn't just call <code>DbMigrator</code> from outside</strong> - as your custom initializer will miss on the whole 'db creation' (e.g. if you wish to seed or something - check my example above). </p> <p><strong>Both things are effectively 'initializers' - so you'd need to integrate them into one</strong>, that'd <code>chain</code> things in some way. Have in mind that <code>order of execution</code> is important (see above ex. for problems) - you should check for 'empty condition', then call <code>DbMigrator</code>, then do your own intialization. I used one initializer as a base class, and merged the other. </p> <p>And if you just want to <code>seed</code> - you can use the migration Configuration, that's the simplest if plausible. </p> <h3>2)</h3> <p>Is pretty 'open ended' and there is no single answer. Usually it works, but issues are expexted... </p> <ul> <li><p>Migrations are 3 things (as I see it) - your code model/entities, your database/tables, and the <code>__MigrationHistory</code> system table in the Db. All 3 need to stay <code>in sync</code>. If you get 'out of sync', you can drop the migration table, recreate migrations (with a flag to keep existing db) and then move on as before - i.e. there are solutions for when with live data. For this see <a href="https://stackoverflow.com/questions/9016709/how-to-ignore-a-table-class-in-ef-4-3-migrations/9623319#9623319">How to ignore a table/class in EF 4.3 migrations</a>, </p></li> <li><p>you'd need permissions to drop/create Db for when moving database, </p></li> <li><p>make sure your connection is right (change in config - and in sync with your DbContext name or ctor), </p></li> <li><p>keep it simple, don't do fancy things or switch connections from code (possible but has problems) etc., </p></li> <li><p>don't <code>mix database / code</code> versions - i.e. one code entities version - one database. If you want to share the same Db with different code versions (e.g. staging, production) - don't (multi-tenant solutions will be available in EF6 - e.g. <a href="https://stackoverflow.com/questions/15955145/entity-framework-with-multiple-models-throws-error-stating-the-model-backing-th/15956419#15956419">this</a>), </p></li> <li><p>if you need to manually apply the database - generate the <code>script</code> via <code>Update-Database</code> - and apply that, don't do things manually or you'll get it wrong (the migration history table) - see <a href="https://stackoverflow.com/questions/10254613/mvc3-and-code-first-migrations/10255051#10255051">this one</a>,</p></li> </ul> <p>...that's just to name the few. It is pretty stable and usable IMO - but if you follow the rules - and know what the limitations are.</p> <hr/> <pre><code>class CreateAndMigrateDatabaseInitializer&lt;TContext, TConfiguration&gt; : CreateDatabaseIfNotExists&lt;TContext&gt;, IDatabaseInitializer&lt;TContext&gt; where TContext : DbContext where TConfiguration : DbMigrationsConfiguration&lt;TContext&gt;, new() { private readonly DbMigrationsConfiguration _configuration; public CreateAndMigrateDatabaseInitializer() { _configuration = new TConfiguration(); } public CreateAndMigrateDatabaseInitializer(string connection) { Contract.Requires(!string.IsNullOrEmpty(connection), "connection"); _configuration = new TConfiguration { TargetDatabase = new DbConnectionInfo(connection) }; } void IDatabaseInitializer&lt;TContext&gt;.InitializeDatabase(TContext context) { var doseed = !context.Database.Exists(); // &amp;&amp; new DatabaseTableChecker().AnyModelTableExists(context); // check to see if to seed - we 'lack' the 'AnyModelTableExists' // ...could be copied/done otherwise if needed... var migrator = new DbMigrator(_configuration); // if (doseed || !context.Database.CompatibleWithModel(false)) if (migrator.GetPendingMigrations().Any()) migrator.Update(); // move on with the 'CreateDatabaseIfNotExists' for the 'Seed' base.InitializeDatabase(context); if (doseed) { Seed(context); context.SaveChanges(); } } protected override void Seed(TContext context) { } } </code></pre>
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    1. POWhat is the correct use of IDatabaseInitializer in EF?
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    1. COThe path that you went in most of your samples is too similar to the path I'm going, I changed some pieces based on your info, and made a question regarding this if you know the solution will be glad to hear it. this is mine: http://stackoverflow.com/questions/17533721/code-first-initialization-and-migration-without-app-config
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    2. CO@LastBye thx - I'll try to take a look, just a bit busy (not very active recently), will take a few days
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    3. COthx maybe I remove it from SO, and post a whole solution in the SkyD. if I did I share the link here as a cm.
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