feat: generated and identity columns for mssql, sqlite, drizzle, typeorm, bun and gorm readers

- mssql: write computed columns (AS (expr) PERSISTED) and identity; read computed definition and identity
- sqlite: write GENERATED ALWAYS AS (expr) STORED; read generated columns via table_xinfo and parse the expression
- drizzle: generatedAlwaysAs / generated(Always|ByDefault)AsIdentity, read and write
- typeorm: asExpression/generatedType and identity decorators, read and write; decorator scan is now quote-aware
- bun, gorm readers: read generated and identity markers
- readmes updated

pkg/readers/sqlite/README.md

@@ -40,6 +40,7 @@ options := &readers.ReaderOptions{
 - Uses pure Go driver (modernc.org/sqlite) - no CGo required
 - Supports both file path and connection string
 - Auto-increment detection for INTEGER PRIMARY KEY columns
+- Generated columns (virtual and stored) are read via `PRAGMA table_xinfo`; the expression is parsed from the `CREATE TABLE` SQL
 - Foreign keys require `PRAGMA foreign_keys = ON` to be set
 
 ## Example Schema

pkg/readers/sqlite/generated.go

@@ -0,0 +1,116 @@
+package sqlite
+
+import (
+	"regexp"
+	"strings"
+)
+
+var generatedAsRegex = regexp.MustCompile(`(?is)\bAS\s*\(`)
+
+// parseGeneratedExpression extracts the expression of a generated column from a CREATE
+// TABLE statement, e.g. `full TEXT GENERATED ALWAYS AS (a || b) STORED` yields `a || b`.
+// It returns "" when the column or its expression cannot be found.
+func parseGeneratedExpression(createSQL, columnName string) string {
+	open := strings.Index(createSQL, "(")
+	if open < 0 {
+		return ""
+	}
+
+	for _, def := range splitTopLevel(createSQL[open+1:]) {
+		if !strings.EqualFold(firstIdentifier(def), columnName) {
+			continue
+		}
+		loc := generatedAsRegex.FindStringIndex(def)
+		if loc == nil {
+			return ""
+		}
+		return balancedParens(def[loc[1]-1:])
+	}
+	return ""
+}
+
+// splitTopLevel splits a table body on commas that are outside parentheses and quotes,
+// stopping at the parenthesis that closes the body.
+func splitTopLevel(body string) []string {
+	var parts []string
+	depth := 0
+	var quote byte
+	start := 0
+	for i := 0; i < len(body); i++ {
+		ch := body[i]
+		if quote != 0 {
+			if ch == quote {
+				quote = 0
+			}
+			continue
+		}
+		switch ch {
+		case '\'', '"', '`':
+			quote = ch
+		case '[':
+			quote = ']'
+		case '(':
+			depth++
+		case ')':
+			if depth == 0 {
+				return append(parts, body[start:i])
+			}
+			depth--
+		case ',':
+			if depth == 0 {
+				parts = append(parts, body[start:i])
+				start = i + 1
+			}
+		}
+	}
+	return append(parts, body[start:])
+}
+
+// firstIdentifier returns the first (possibly quoted) identifier of a column definition.
+func firstIdentifier(def string) string {
+	def = strings.TrimSpace(def)
+	if def == "" {
+		return ""
+	}
+	switch def[0] {
+	case '"', '\'', '`':
+		if end := strings.IndexByte(def[1:], def[0]); end >= 0 {
+			return def[1 : 1+end]
+		}
+	case '[':
+		if end := strings.IndexByte(def, ']'); end >= 0 {
+			return def[1:end]
+		}
+	}
+	if end := strings.IndexAny(def, " \t\r\n"); end >= 0 {
+		return def[:end]
+	}
+	return def
+}
+
+// balancedParens returns the text inside the parenthesis group that starts at s[0].
+func balancedParens(s string) string {
+	depth := 0
+	var quote byte
+	for i := 0; i < len(s); i++ {
+		ch := s[i]
+		if quote != 0 {
+			if ch == quote {
+				quote = 0
+			}
+			continue
+		}
+		switch ch {
+		case '\'', '"':
+			quote = ch
+		case '(':
+			depth++
+		case ')':
+			depth--
+			if depth == 0 {
+				return strings.TrimSpace(s[1:i])
+			}
+		}
+	}
+	return ""
+}

pkg/readers/sqlite/generated_test.go

@@ -0,0 +1,64 @@
+package sqlite
+
+import (
+	"database/sql"
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"git.warky.dev/wdevs/relspecgo/pkg/readers"
+)
+
+func TestParseGeneratedExpression(t *testing.T) {
+	createSQL := `CREATE TABLE people (
+		id INTEGER PRIMARY KEY,
+		"first" TEXT,
+		last TEXT,
+		full_name TEXT GENERATED ALWAYS AS (coalesce("first", '') || ' ' || last) STORED,
+		initials TEXT AS (substr("first", 1, 1) || substr(last, 1, 1)),
+		plain TEXT NOT NULL
+	)`
+
+	tests := []struct {
+		column string
+		want   string
+	}{
+		{"full_name", `coalesce("first", '') || ' ' || last`},
+		{"initials", `substr("first", 1, 1) || substr(last, 1, 1)`},
+		{"plain", ""},
+		{"missing", ""},
+	}
+	for _, tt := range tests {
+		t.Run(tt.column, func(t *testing.T) {
+			assert.Equal(t, tt.want, parseGeneratedExpression(createSQL, tt.column))
+		})
+	}
+}
+
+func TestReader_GeneratedColumns(t *testing.T) {
+	dbPath := filepath.Join(t.TempDir(), "gen.db")
+	db, err := sql.Open("sqlite", dbPath)
+	require.NoError(t, err)
+	_, err = db.Exec(`CREATE TABLE people (
+		id INTEGER PRIMARY KEY,
+		first TEXT,
+		last TEXT,
+		full_name TEXT GENERATED ALWAYS AS (first || ' ' || last) STORED,
+		initials TEXT AS (substr(first, 1, 1) || substr(last, 1, 1))
+	)`)
+	require.NoError(t, err)
+	require.NoError(t, db.Close())
+
+	got, err := NewReader(&readers.ReaderOptions{FilePath: dbPath}).ReadDatabase()
+	require.NoError(t, err)
+
+	cols := got.Schemas[0].Tables[0].Columns
+	require.Contains(t, cols, "full_name", "generated columns must be read")
+	assert.True(t, cols["full_name"].Generated)
+	assert.Equal(t, "first || ' ' || last", cols["full_name"].GenerationExpression)
+	assert.True(t, cols["initials"].Generated)
+	assert.Equal(t, "substr(first, 1, 1) || substr(last, 1, 1)", cols["initials"].GenerationExpression)
+	assert.False(t, cols["first"].Generated)
+}

pkg/readers/sqlite/queries.go

@@ -75,7 +75,8 @@ func (r *Reader) queryViews() ([]*models.View, error) {
 
 // queryColumns retrieves all columns for a given table or view
 func (r *Reader) queryColumns(tableName string) (map[string]*models.Column, error) {
-	query := fmt.Sprintf("PRAGMA table_info(%s)", tableName)
+	// table_xinfo, unlike table_info, also lists generated columns (hidden = 2 virtual, 3 stored)
+	query := fmt.Sprintf("PRAGMA table_xinfo(%s)", tableName)
 
 	rows, err := r.db.QueryContext(r.ctx, query)
 	if err != nil {
@@ -84,24 +85,38 @@ func (r *Reader) queryColumns(tableName string) (map[string]*models.Column, erro
 	defer rows.Close()
 
 	columns := make(map[string]*models.Column)
+	var tableSQL string
+	tableSQLLoaded := false
 
 	for rows.Next() {
 		var cid int
 		var name, dataType string
-		var notNull, pk int
+		var notNull, pk, hidden int
 		var defaultValue *string
 
-		if err := rows.Scan(&cid, &name, &dataType, &notNull, &defaultValue, &pk); err != nil {
+		if err := rows.Scan(&cid, &name, &dataType, &notNull, &defaultValue, &pk, &hidden); err != nil {
 			return nil, err
 		}
 
+		// Hidden virtual-table columns (hidden = 1) are not part of the schema
+		if hidden == 1 {
+			continue
+		}
+
 		column := models.InitColumn(name, tableName, "main")
 		column.Type = r.mapDataType(strings.ToUpper(dataType))
 		column.NotNull = (notNull == 1)
 		column.IsPrimaryKey = (pk > 0)
 		column.Sequence = uint(cid + 1)
 
-		if defaultValue != nil {
+		if hidden == 2 || hidden == 3 {
+			column.Generated = true
+			if !tableSQLLoaded {
+				tableSQL = r.tableSQL(tableName)
+				tableSQLLoaded = true
+			}
+			column.GenerationExpression = parseGeneratedExpression(tableSQL, name)
+		} else if defaultValue != nil {
 			column.Default = *defaultValue
 		}
 
@@ -116,6 +131,16 @@ func (r *Reader) queryColumns(tableName string) (map[string]*models.Column, erro
 	return columns, rows.Err()
 }
 
+// tableSQL returns the CREATE TABLE statement of a table, or "" when it cannot be read.
+func (r *Reader) tableSQL(tableName string) string {
+	var sql string
+	err := r.db.QueryRowContext(r.ctx, `SELECT sql FROM sqlite_master WHERE type = 'table' AND name = ?`, tableName).Scan(&sql)
+	if err != nil {
+		return ""
+	}
+	return sql
+}
+
 // isAutoIncrement checks if a column is autoincrement
 func (r *Reader) isAutoIncrement(tableName, columnName string) bool {
 	// Check sqlite_sequence table or parse CREATE TABLE statement