Add missing attributes to column info in virtual schema (#789)

When a table was added, `pgroll` did not store all required column
metadata. Default values and comments were missing from columns. So when
`pgroll` tried to duplicate the column, these got lost.

Example to reproduce the issue:
```json
{
    "operations": [
        {
            "create_table": {
                "name": "useres",
                "comment": "my_comment",
                "columns": [
                    {
                        "name": "id",
                        "type": "uuid",
                        "pk": true,
                        "nullable": false,
                        "default": "gen_random_uuid()",
                        "comment": "my_comment"
                    }
                ]
            }
        },
        {
            "create_constraint": {
                "table": "users",
                "columns": ["id"],
                "type": "unique",
                "name": "my_unique",
                "up": {
                    "id": "id"
                },
                "down": {
                    "id": "id"
                }
            }
        }
    ]
}
```

Author: kvch

pkg/migrations/op_common_test.go

@@ -190,6 +190,13 @@ func ColumnMustNotHaveComment(t *testing.T, db *sql.DB, schema, table, column st
 	}
 }
 
+func ColumnMustHaveDefault(t *testing.T, db *sql.DB, schema, table, column, expectedDefault string) {
+	t.Helper()
+	if !columnHasDefault(t, db, schema, table, column, &expectedDefault) {
+		t.Fatalf("Expected column %q to have default value %q", column, expectedDefault)
+	}
+}
+
 func ColumnMustBePK(t *testing.T, db *sql.DB, schema, table, column string) {
 	t.Helper()
 	if !columnMustBePK(t, db, schema, table, column) {
@@ -710,6 +717,27 @@ func columnHasComment(t *testing.T, db *sql.DB, schema, table, column string, ex
 	return actualComment != nil && *expectedComment == *actualComment
 }
 
+func columnHasDefault(t *testing.T, db *sql.DB, schema, table, column string, expectedDefault *string) bool {
+	t.Helper()
+
+	var actualDefault *string
+	err := db.QueryRow(`
+    SELECT column_default
+    FROM information_schema.columns
+    WHERE table_schema = $1
+    AND table_name = $2
+    AND column_name = $3
+  `,
+		schema, table, column).Scan(&actualDefault)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if expectedDefault == nil {
+		return actualDefault == nil
+	}
+	return actualDefault != nil && *expectedDefault == *actualDefault
+}
+
 func columnMustBePK(t *testing.T, db *sql.DB, schema, table, column string) bool {
 	t.Helper()
 

pkg/migrations/op_create_constraint_test.go

@@ -1225,6 +1225,105 @@ func TestCreateConstraintInMultiOperationMigrations(t *testing.T) {
 				TableMustBeCleanedUp(t, db, schema, "products", "name")
 			},
 		},
+		{
+			name: "create table with comment and default on column, add unique constraint",
+			migrations: []migrations.Migration{
+				{
+					Name: "01_create_table",
+					Operations: migrations.Operations{
+						&migrations.OpCreateTable{
+							Name: "items",
+							Columns: []migrations.Column{
+								{
+									Name: "id",
+									Type: "int",
+									Pk:   true,
+								},
+								{
+									Name:    "name",
+									Type:    "text",
+									Default: ptr("'Pixel'"),
+									Comment: ptr("my important comment"),
+								},
+							},
+						},
+						&migrations.OpCreateConstraint{
+							Table:   "items",
+							Type:    migrations.OpCreateConstraintTypeUnique,
+							Name:    "unique_item_name",
+							Columns: []string{"name"},
+							Up: map[string]string{
+								"name": "name",
+							},
+							Down: map[string]string{
+								"name": "name",
+							},
+						},
+					},
+				},
+			},
+			afterStart: func(t *testing.T, db *sql.DB, schema string) {
+				// Column must have comment set
+				ColumnMustHaveComment(t, db, schema, "items", "name", "my important comment")
+				// Column must have default value
+				ColumnMustHaveDefault(t, db, schema, "items", "name", "'Pixel'::text")
+				// Can insert a row into the new schema
+				MustInsert(t, db, schema, "01_create_table", "items", map[string]string{
+					"id":   "1",
+					"name": "apple",
+				})
+
+				// Can insert a row into the new schema that meets the constraint
+				MustInsert(t, db, schema, "01_create_table", "items", map[string]string{
+					"id":   "2",
+					"name": "banana",
+				})
+
+				// Can't insert a row into the new schema that violates the constraint
+				MustNotInsert(t, db, schema, "01_create_table", "items", map[string]string{
+					"id":   "3",
+					"name": "apple",
+				}, testutils.UniqueViolationErrorCode)
+
+				// The new view has the expected rows
+				rows := MustSelect(t, db, schema, "01_create_table", "items")
+				assert.Equal(t, []map[string]any{
+					{"id": 1, "name": "apple"},
+					{"id": 2, "name": "banana"},
+				}, rows)
+
+				// The old view has the expected rows
+				rows = MustSelect(t, db, schema, "01_create_table", "items")
+				assert.Equal(t, []map[string]any{
+					{"id": 1, "name": "apple"},
+					{"id": 2, "name": "banana"},
+				}, rows)
+			},
+			afterRollback: func(t *testing.T, db *sql.DB, schema string) {},
+			afterComplete: func(t *testing.T, db *sql.DB, schema string) {
+				// Column comment must be preserved
+				ColumnMustHaveComment(t, db, schema, "items", "name", "my important comment")
+				// Column must have default value
+				ColumnMustHaveDefault(t, db, schema, "items", "name", "'Pixel'::text")
+				// Can insert a row into the new schema that meets the constraint
+				MustInsert(t, db, schema, "01_create_table", "items", map[string]string{
+					"id":   "3",
+					"name": "carrot",
+				})
+
+				// Can't insert a row into the new schema that violates the constraint
+				MustNotInsert(t, db, schema, "01_create_table", "items", map[string]string{
+					"id":   "4",
+					"name": "carrot",
+				}, testutils.UniqueViolationErrorCode)
+
+				// The new view has the expected rows
+				rows := MustSelect(t, db, schema, "01_create_table", "items")
+				assert.Equal(t, []map[string]any{
+					{"id": 3, "name": "carrot"},
+				}, rows)
+			},
+		},
 	})
 }
 

pkg/migrations/op_create_table.go

@@ -207,10 +207,14 @@ func (o *OpCreateTable) updateSchema(s *schema.Schema) *schema.Schema {
 			Unique:   col.Unique,
 			Nullable: col.Nullable,
 			Type:     col.Type,
+			Default:  col.Default,
 		}
 		if col.Pk {
 			primaryKeys = append(primaryKeys, col.Name)
 		}
+		if col.Comment != nil {
+			columns[col.Name].Comment = *col.Comment
+		}
 	}
 
 	uniqueConstraints := make(map[string]*schema.UniqueConstraint, 0)