Basic column & database collation support

Support only for collation support implemented upstream, PostgreSQL-
specific functionality still remains.

Part of #406

src/EFCore.PG/Migrations/NpgsqlMigrationsSqlGenerator.cs

@@ -10,7 +10,6 @@
 using Microsoft.EntityFrameworkCore.Migrations;
 using Microsoft.EntityFrameworkCore.Migrations.Operations;
 using Microsoft.EntityFrameworkCore.Storage;
-using Npgsql.EntityFrameworkCore.PostgreSQL;
 using Npgsql.EntityFrameworkCore.PostgreSQL.Infrastructure.Internal;
 using Npgsql.EntityFrameworkCore.PostgreSQL.Metadata;
 using Npgsql.EntityFrameworkCore.PostgreSQL.Metadata.Internal;
@@ -353,11 +352,15 @@ protected override void Generate(AlterColumnOperation operation, IModel model, M
             var alterBase = $"ALTER TABLE {DelimitIdentifier(operation.Table, operation.Schema)} " +
                             $"ALTER COLUMN {DelimitIdentifier(operation.Name)} ";
 
-            // TYPE
+            // TYPE + COLLATION
             builder.Append(alterBase)
                 .Append("TYPE ")
-                .Append(type)
-                .AppendLine(";");
+                .Append(type);
+
+            if (operation.Collation != operation.OldColumn.Collation)
+                builder.Append(" COLLATE ").Append(DelimitIdentifier(operation.Collation ?? "default"));
+
+            builder.AppendLine(";");
 
             // NOT NULL
             builder.Append(alterBase)
@@ -736,20 +739,30 @@ protected virtual void Generate(NpgsqlCreateDatabaseOperation operation, [CanBeN
                 .Append("CREATE DATABASE ")
                 .Append(DelimitIdentifier(operation.Name));
 
-            if (operation.Template != null)
+            if (!string.IsNullOrEmpty(operation.Template))
             {
                 builder
-                    .Append(" TEMPLATE ")
+                    .AppendLine()
+                    .Append("TEMPLATE ")
                     .Append(DelimitIdentifier(operation.Template));
             }
 
-            if (operation.Tablespace != null)
+            if (!string.IsNullOrEmpty(operation.Tablespace))
             {
                 builder
-                    .Append(" TABLESPACE ")
+                    .AppendLine()
+                    .Append("TABLESPACE ")
                     .Append(DelimitIdentifier(operation.Tablespace));
             }
 
+            if (!string.IsNullOrEmpty(operation.Collation))
+            {
+                builder
+                    .AppendLine()
+                    .Append("COLLATE ")
+                    .Append(DelimitIdentifier(operation.Collation));
+            }
+
             builder.AppendLine(";");
 
             EndStatement(builder, suppressTransaction: true);
@@ -782,6 +795,9 @@ public virtual void Generate(NpgsqlDropDatabaseOperation operation, [CanBeNull]
             Check.NotNull(model, nameof(model));
             Check.NotNull(builder, nameof(builder));
 
+            if (operation.Collation != operation.OldDatabase.Collation)
+                throw new NotSupportedException("PostgreSQL does not support altering the collation on an existing database.");
+
             GenerateEnumStatements(operation, model, builder);
             GenerateRangeStatements(operation, model, builder);
 
@@ -1174,13 +1190,29 @@ protected override void Generate(CreateSequenceOperation operation, IModel model
                 operation.ComputedColumnSql = ColumnsToTsVector(tsVectorIncludedColumns, tsVectorConfig, model, schema, table);
             }
 
-            base.ColumnDefinition(
-                schema,
-                table,
-                name,
-                operation,
-                model,
-                builder);
+            if (operation.ComputedColumnSql != null)
+            {
+                ComputedColumnDefinition(schema, table, name, operation, model, builder);
+
+                return;
+            }
+
+            var columnType = operation.ColumnType ?? GetColumnType(schema, table, name, operation, model);
+            builder
+                .Append(DelimitIdentifier(name))
+                .Append(" ")
+                .Append(columnType);
+
+            if (operation.Collation != null)
+            {
+                builder
+                    .Append(" COLLATE ")
+                    .Append(DelimitIdentifier(operation.Collation));
+            }
+
+            builder.Append(operation.IsNullable ? " NULL" : " NOT NULL");
+
+            DefaultValue(operation.DefaultValue, operation.DefaultValueSql, columnType, builder);
 
             if (valueGenerationStrategy.IsIdentity())
                 IdentityDefinition(operation, builder);
@@ -1302,7 +1334,16 @@ long Max(Type type)
             builder
                 .Append(DelimitIdentifier(name))
                 .Append(" ")
-                .Append(operation.ColumnType ?? GetColumnType(schema, table, name, operation, model))
+                .Append(operation.ColumnType ?? GetColumnType(schema, table, name, operation, model));
+
+            if (operation.Collation != null)
+            {
+                builder
+                    .Append(" COLLATE ")
+                    .Append(DelimitIdentifier(operation.Collation));
+            }
+
+            builder
                 .Append(" GENERATED ALWAYS AS (")
                 .Append(operation.ComputedColumnSql)
                 .Append(") STORED");

src/EFCore.PG/Migrations/Operations/NpgsqlCreateDatabaseOperation.cs

@@ -3,7 +3,7 @@
 
 namespace Npgsql.EntityFrameworkCore.PostgreSQL.Migrations.Operations
 {
-    public class NpgsqlCreateDatabaseOperation : MigrationOperation
+    public class NpgsqlCreateDatabaseOperation : DatabaseOperation
     {
         public virtual string Name { get;[param: NotNull] set; }
         [CanBeNull]

src/EFCore.PG/Scaffolding/Internal/NpgsqlDatabaseModelFactory.cs

@@ -245,6 +245,7 @@ public override DatabaseModel Create(DbConnection dbConnection, DatabaseModelFac
   basetyp.typname AS basetypname,
   attname,
   description,
+  collname,
   attisdropped,
   {(connection.PostgreSqlVersion >= new Version(10, 0) ? "attidentity" : "''::\"char\" as attidentity")},
   {(connection.PostgreSqlVersion >= new Version(12, 0) ? "attgenerated" : "''::\"char\" as attgenerated")},
@@ -277,6 +278,7 @@ ELSE NULL
 LEFT JOIN pg_type AS elemtyp ON (elemtyp.oid = typ.typelem)
 LEFT JOIN pg_type AS basetyp ON (basetyp.oid = typ.typbasetype)
 LEFT JOIN pg_description AS des ON des.objoid = cls.oid AND des.objsubid = attnum
+LEFT JOIN pg_collation as coll ON coll.oid = attr.attcollation
 -- Bring in identity sequences the depend on this column
 LEFT JOIN pg_depend AS dep ON dep.refobjid = cls.oid AND dep.refobjsubid = attr.attnum AND dep.deptype = 'i'
 {(connection.PostgreSqlVersion >= new Version(10, 0) ? "LEFT JOIN pg_sequence AS seq ON seq.seqrelid = dep.objid" : "")}
@@ -410,6 +412,9 @@ ELSE NULL
                         if (record.GetValueOrDefault<string>("description") is string comment)
                             column.Comment = comment;
 
+                        if (record.GetValueOrDefault<string>("collname") is string collation && collation != "default")
+                            column.Collation = collation;
+
                         logger.ColumnFound(
                             DisplayName(tableSchema, tableName),
                             column.Name,

test/EFCore.PG.FunctionalTests/MigrationsNpgsqlTest.cs

@@ -53,7 +53,7 @@ public override async Task Create_table_all_settings()
                 @"CREATE TABLE dbo2.""People"" (
     ""CustomId"" integer NOT NULL,
     ""EmployerId"" integer NOT NULL,
-    ""SSN"" character varying(11) NOT NULL,
+    ""SSN"" character varying(11) COLLATE ""POSIX"" NOT NULL,
     CONSTRAINT ""PK_People"" PRIMARY KEY (""CustomId""),
     CONSTRAINT ""AK_People_SSN"" UNIQUE (""SSN""),
     CONSTRAINT ""CK_EmployerId"" CHECK (""EmployerId"" > 0),
@@ -533,6 +533,30 @@ public override async Task Add_column_with_comment()
 COMMENT ON COLUMN ""People"".""FullName"" IS 'My comment';");
         }
 
+        [ConditionalFact]
+        public override async Task Add_column_with_collation()
+        {
+            await base.Add_column_with_collation();
+
+            AssertSql(
+                @"ALTER TABLE ""People"" ADD ""Name"" text COLLATE ""POSIX"" NULL;");
+        }
+
+        [ConditionalFact]
+        public override async Task Add_column_computed_with_collation()
+        {
+            if (TestEnvironment.PostgresVersion.IsUnder(12))
+            {
+                await Assert.ThrowsAsync<NotSupportedException>(() => base.Add_column_computed_with_collation());
+                return;
+            }
+
+            await base.Add_column_computed_with_collation();
+
+            AssertSql(
+                @"ALTER TABLE ""People"" ADD ""Name"" text COLLATE ""POSIX"" GENERATED ALWAYS AS ('hello') STORED;");
+        }
+
         public override async Task Add_column_shared()
         {
             await base.Add_column_shared();
@@ -1267,6 +1291,28 @@ public virtual async Task Alter_column_restart_identity()
 ALTER TABLE ""People"" ALTER COLUMN ""Id"" RESTART WITH 20;");
         }
 
+        [Fact]
+        public override async Task Alter_column_set_collation()
+        {
+            await base.Alter_column_set_collation();
+
+            AssertSql(
+                @"ALTER TABLE ""People"" ALTER COLUMN ""Name"" TYPE text COLLATE ""POSIX"";
+ALTER TABLE ""People"" ALTER COLUMN ""Name"" DROP NOT NULL;
+ALTER TABLE ""People"" ALTER COLUMN ""Name"" DROP DEFAULT;");
+        }
+
+        [Fact]
+        public override async Task Alter_column_reset_collation()
+        {
+            await base.Alter_column_reset_collation();
+
+            AssertSql(
+                @"ALTER TABLE ""People"" ALTER COLUMN ""Name"" TYPE text COLLATE ""default"";
+ALTER TABLE ""People"" ALTER COLUMN ""Name"" DROP NOT NULL;
+ALTER TABLE ""People"" ALTER COLUMN ""Name"" DROP DEFAULT;");
+        }
+
         public override async Task Drop_column()
         {
             await base.Drop_column();
@@ -2129,6 +2175,8 @@ public virtual Task Alter_enum_change_label_not_supported()
 
         #endregion
 
+        protected override string NonDefaultCollation => "POSIX";
+
         public class MigrationsNpgsqlFixture : MigrationsFixtureBase
         {
             protected override string StoreName { get; } = nameof(MigrationsNpgsqlTest);

test/EFCore.PG.FunctionalTests/Scaffolding/NpgsqlDatabaseModelFactoryTest.cs

@@ -1549,6 +1549,27 @@ public void Identity_with_sequence_options_all()
                 },
                 "DROP TABLE identity");
 
+
+        [Fact]
+        public void Column_collation_is_set()
+            => Test(
+                @"
+CREATE TABLE columns_with_collation (
+    id int,
+    default_collation TEXT,
+    non_default_collation TEXT COLLATE ""POSIX""
+);",
+                Enumerable.Empty<string>(),
+                Enumerable.Empty<string>(),
+                dbModel =>
+                {
+                    var columns = dbModel.Tables.Single().Columns;
+
+                    Assert.Null(columns.Single(c => c.Name == "default_collation").Collation);
+                    Assert.Equal("POSIX", columns.Single(c => c.Name == "non_default_collation").Collation);
+                },
+                @"DROP TABLE columns_with_collation");
+
         [Fact]
         public void Index_method()
             => Test(@"

test/EFCore.PG.Tests/Migrations/NpgsqlMigrationSqlGeneratorTest.cs

@@ -23,6 +23,18 @@ public virtual void CreateDatabaseOperation()
 ");
         }
 
+        [ConditionalFact]
+        public virtual void CreateDatabaseOperation_with_collation()
+        {
+            Generate(
+                new NpgsqlCreateDatabaseOperation { Name = "Northwind", Collation = "POSIX" });
+
+            AssertSql(
+                @"CREATE DATABASE ""Northwind""
+COLLATE ""POSIX"";
+");
+        }
+
         [Fact]
         public virtual void CreateDatabaseOperation_with_template()
         {
@@ -33,7 +45,8 @@ public virtual void CreateDatabaseOperation_with_template()
             });
 
             AssertSql(
-                @"CREATE DATABASE ""Northwind"" TEMPLATE ""MyTemplate"";
+                @"CREATE DATABASE ""Northwind""
+TEMPLATE ""MyTemplate"";
 ");
         }
 
@@ -47,7 +60,8 @@ public virtual void CreateDatabaseOperation_with_tablespace()
             });
 
             AssertSql(
-                @"CREATE DATABASE some_db TABLESPACE ""MyTablespace"";
+                @"CREATE DATABASE some_db
+TABLESPACE ""MyTablespace"";
 ");
         }