Allow database template on context

Closes #2

src/Npgsql.EntityFrameworkCore.PostgreSQL/Metadata/INpgsqlModelAnnotations.cs

@@ -30,5 +30,6 @@ namespace Microsoft.EntityFrameworkCore.Metadata
     public interface INpgsqlModelAnnotations : IRelationalModelAnnotations
     {
         IReadOnlyList<IPostgresExtension> PostgresExtensions { get; }
+        string DatabaseTemplate { get; }
     }
 }

src/Npgsql.EntityFrameworkCore.PostgreSQL/Metadata/Internal/NpgsqlAnnotationNames.cs

@@ -33,5 +33,6 @@ public static class NpgsqlAnnotationNames
         public const string SequenceSchema = "SequenceSchema";
         public const string IndexMethod = "IndexMethod";
         public const string PostgresExtensionPrefix = "PostgresExtension:";
+        public const string DatabaseTemplate = "DatabaseTemplate";
     }
 }

src/Npgsql.EntityFrameworkCore.PostgreSQL/Metadata/Internal/NpgsqlFullAnnotationNames.cs

@@ -35,6 +35,7 @@ protected NpgsqlFullAnnotationNames(string prefix)
             SequenceSchema = prefix + NpgsqlAnnotationNames.SequenceSchema;
             IndexMethod = prefix + NpgsqlAnnotationNames.IndexMethod;
             PostgresExtensionPrefix = prefix + NpgsqlAnnotationNames.PostgresExtensionPrefix;
+            DatabaseTemplate = prefix + NpgsqlAnnotationNames.DatabaseTemplate;
         }
 
         public new static NpgsqlFullAnnotationNames Instance { get; } = new NpgsqlFullAnnotationNames(NpgsqlAnnotationNames.Prefix);
@@ -46,5 +47,6 @@ protected NpgsqlFullAnnotationNames(string prefix)
         public readonly string SequenceSchema;
         public readonly string IndexMethod;
         public readonly string PostgresExtensionPrefix;
+        public readonly string DatabaseTemplate;
     }
 }

src/Npgsql.EntityFrameworkCore.PostgreSQL/Metadata/NpgsqlModelAnnotations.cs

@@ -6,6 +6,7 @@
 using JetBrains.Annotations;
 using Microsoft.EntityFrameworkCore.Metadata;
 using Microsoft.EntityFrameworkCore.Metadata.Internal;
+using Microsoft.EntityFrameworkCore.Utilities;
 
 namespace Microsoft.EntityFrameworkCore.Metadata
 {
@@ -29,5 +30,18 @@ public virtual PostgresExtension GetOrAddPostgresExtension([CanBeNull] string na
 
         public virtual IReadOnlyList<IPostgresExtension> PostgresExtensions
             => PostgresExtension.GetPostgresExtensions(Model, NpgsqlFullAnnotationNames.Instance.PostgresExtensionPrefix).ToList();
+
+        public virtual string DatabaseTemplate
+        {
+            get { return (string)Annotations.GetAnnotation(NpgsqlFullAnnotationNames.Instance.DatabaseTemplate, null); }
+            [param: CanBeNull]
+            set { SetDatabaseTemplate(value); }
+        }
+
+        protected virtual bool SetDatabaseTemplate([CanBeNull] string value)
+            => Annotations.SetAnnotation(
+                NpgsqlFullAnnotationNames.Instance.DatabaseTemplate,
+                null,
+                Check.NullButNotEmpty(value, nameof(value)));
     }
 }

src/Npgsql.EntityFrameworkCore.PostgreSQL/Migrations/NpgsqlMigrationsSqlGenerator.cs

@@ -288,8 +288,7 @@ protected override void Generate(EnsureSchemaOperation operation, IModel model,
 
             builder
                 .Append("CREATE SCHEMA IF NOT EXISTS ")
-                .Append(SqlGenerationHelper.DelimitIdentifier(operation.Name))
-                .AppendLine(SqlGenerationHelper.StatementTerminator);
+                .Append(SqlGenerationHelper.DelimitIdentifier(operation.Name));
         }
 
         public virtual void Generate(NpgsqlCreateDatabaseOperation operation, IModel model, RelationalCommandListBuilder builder)
@@ -299,8 +298,14 @@ public virtual void Generate(NpgsqlCreateDatabaseOperation operation, IModel mod
 
             builder
                 .Append("CREATE DATABASE ")
-                .Append(SqlGenerationHelper.DelimitIdentifier(operation.Name))
-                .AppendLine(SqlGenerationHelper.StatementTerminator);
+                .Append(SqlGenerationHelper.DelimitIdentifier(operation.Name));
+
+            if (operation.Template != null)
+            {
+                builder
+                    .Append(" TEMPLATE ")
+                    .Append(SqlGenerationHelper.DelimitIdentifier(operation.Template));
+            }
         }
 
         public virtual void Generate(NpgsqlDropDatabaseOperation operation, IModel model, RelationalCommandListBuilder builder)
@@ -321,7 +326,7 @@ public virtual void Generate(NpgsqlDropDatabaseOperation operation, IModel model
                     "SELECT pg_terminate_backend(pg_stat_activity.pid) FROM pg_stat_activity WHERE pg_stat_activity.datname = '")
                 .Append(operation.Name)
                 .Append("'")
-                .AppendLine(SqlGenerationHelper.StatementTerminator)
+                .EndCommand()
                 .Append("DROP DATABASE ")
                 .Append(dbName);
         }
@@ -348,8 +353,6 @@ public virtual void Generate(NpgsqlCreatePostgresExtensionOperation operation, I
                     .Append(" VERSION ")
                     .Append(SqlGenerationHelper.DelimitIdentifier(operation.Version));
             }
-
-            builder.AppendLine(SqlGenerationHelper.StatementTerminator);
         }
 
         protected override void Generate(DropIndexOperation operation, IModel model, RelationalCommandListBuilder builder)

src/Npgsql.EntityFrameworkCore.PostgreSQL/Migrations/Operations/NpgsqlCreateDatabaseOperation.cs

@@ -28,5 +28,7 @@ namespace Microsoft.EntityFrameworkCore.Migrations.Operations
     public class NpgsqlCreateDatabaseOperation : MigrationOperation
     {
         public virtual string Name { get;[param: NotNull] set; }
+        [CanBeNull]
+        public virtual string Template { get; set; }
     }
 }

src/Npgsql.EntityFrameworkCore.PostgreSQL/NpgsqlModelBuilderExtensions.cs

@@ -24,5 +24,16 @@ public static class NpgsqlModelBuilderExtensions
             return new NpgsqlPostgresExtensionBuilder(
                 modelBuilder.Model.Npgsql().GetOrAddPostgresExtension(name, schema));
         }
+
+        public static ModelBuilder HasDatabaseTemplate(
+            [NotNull] this ModelBuilder modelBuilder,
+            [NotNull] string templateDatabaseName)
+        {
+            Check.NotNull(modelBuilder, nameof(modelBuilder));
+            Check.NotEmpty(templateDatabaseName, nameof(templateDatabaseName));
+
+            modelBuilder.Model.Npgsql().DatabaseTemplate = templateDatabaseName;
+            return modelBuilder;
+        }
     }
 }

src/Npgsql.EntityFrameworkCore.PostgreSQL/Storage/Internal/NpgsqlDatabaseCreator.cs

@@ -117,7 +117,7 @@ FROM information_schema.tables
                 ");
 
         IEnumerable<IRelationalCommand> CreateCreateOperations()
-            => _migrationsSqlGenerator.Generate(new[] { new NpgsqlCreateDatabaseOperation { Name = _connection.DbConnection.Database } });
+            => _migrationsSqlGenerator.Generate(new[] { new NpgsqlCreateDatabaseOperation { Name = _connection.DbConnection.Database, Template = Model.Npgsql().DatabaseTemplate } });
 
         /// <summary>
         /// Creates migration operations that should take place immediately after creating the database,

test/Npgsql.EntityFrameworkCore.PostgreSQL.Tests/Migrations/NpgsqlMigrationSqlGeneratorTest.cs

@@ -162,6 +162,30 @@ public override void CreateIndexOperation_nonunique()
                 Sql);
         }
 
+        [Fact]
+        public virtual void CreateDatabaseOperation()
+        {
+            Generate(new NpgsqlCreateDatabaseOperation { Name = "Northwind" });
+
+            Assert.Equal(
+                @"CREATE DATABASE ""Northwind"";" + EOL,
+                Sql);
+        }
+
+        [Fact]
+        public virtual void CreateDatabaseOperation_with_template()
+        {
+            Generate(new NpgsqlCreateDatabaseOperation
+            {
+                Name = "Northwind",
+                Template = "MyTemplate"
+            });
+
+            Assert.Equal(
+                @"CREATE DATABASE ""Northwind"" TEMPLATE ""MyTemplate"";" + EOL,
+                Sql);
+        }
+
         public override void CreateSequenceOperation_with_minValue_and_maxValue()
         {
             base.CreateSequenceOperation_with_minValue_and_maxValue();