Add index with entity framework code first (CTP5)

Question

Is there a way to get EF CTP5 to create an index when it creates a schema?

Update: See here for how EF 6.1 handles this (as pointed out by juFo belo

Answer 1

As some mentioned in the comments to Mortezas answer there is a CreateIndex/DropIndex method if you use migrations.

But if you are in "debug"/development mode and is changing the schema all the time and are recreating the database every time you can use the example mentioned in Morteza answer.

To make it a little easier, I have written a very simple extension method to make it strongly typed, as inspiration that I want to share with anyone who reads this question and maybe would like this approach aswell. Just change it to fit your needs and way of naming indexes.

You use it like this: context.Database.CreateUniqueIndex(x => x.Name);

.

    public static void CreateUniqueIndex(this Database database, Expression> expression)
    {
        if (database == null)
            throw new ArgumentNullException("database");

        // Assumes singular table name matching the name of the Model type

        var tableName = typeof(TModel).Name;
        var columnName = GetLambdaExpressionName(expression.Body);
        var indexName = string.Format("IX_{0}_{1}", tableName, columnName);

        var createIndexSql = string.Format("CREATE UNIQUE INDEX {0} ON {1} ({2})", indexName, tableName, columnName);

        database.ExecuteSqlCommand(createIndexSql);
    }

    public static string GetLambdaExpressionName(Expression expression)
    {
        MemberExpression memberExp = expression as MemberExpression;

        if (memberExp == null)
        {
            // Check if it is an UnaryExpression and unwrap it
            var unaryExp = expression as UnaryExpression;
            if (unaryExp != null)
                memberExp = unaryExp.Operand as MemberExpression;
        }

        if (memberExp == null)
            throw new ArgumentException("Cannot get name from expression", "expression");

        return memberExp.Member.Name;
    }

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Update: From version 6.1 and onwards there is an [Index] attribute available.

For more info, see http://msdn.microsoft.com/en-US/data/jj591583#Index