chore: import upstream snapshot with attribution

model/postgres/postgres.go

@@ -0,0 +1,414 @@
+// Package postgres provides a PostgreSQL model.Model implementation.
+// Uses lib/pq driver. Best for production deployments with rich query support.
+package postgres
+
+import (
+	"context"
+	"database/sql"
+	"fmt"
+	"reflect"
+	"strings"
+	"sync"
+
+	_ "github.com/lib/pq"
+
+	"go-micro.dev/v6/model"
+)
+
+type postgresModel struct {
+	db      *sql.DB
+	mu      sync.RWMutex
+	schemas map[string]*model.Schema
+	types   map[reflect.Type]*model.Schema
+}
+
+// New creates a new Postgres model. DSN is a connection string
+// (e.g., "postgres://user:pass@localhost/dbname?sslmode=disable").
+func New(dsn string) model.Model {
+	db, err := sql.Open("postgres", dsn)
+	if err != nil {
+		panic(fmt.Sprintf("model/postgres: failed to open: %v", err))
+	}
+	return &postgresModel{
+		db:      db,
+		schemas: make(map[string]*model.Schema),
+		types:   make(map[reflect.Type]*model.Schema),
+	}
+}
+
+func (d *postgresModel) Init(opts ...model.Option) error {
+	return d.db.Ping()
+}
+
+func (d *postgresModel) Register(v interface{}, opts ...model.RegisterOption) error {
+	schema := model.BuildSchema(v, opts...)
+	t := model.ResolveType(v)
+
+	d.mu.Lock()
+	d.schemas[schema.Table] = schema
+	d.types[t] = schema
+	d.mu.Unlock()
+
+	var cols []string
+	for _, f := range schema.Fields {
+		colType := goTypeToPostgres(f.Type)
+		col := fmt.Sprintf("%s %s", quoteIdent(f.Column), colType)
+		if f.IsKey {
+			col += " PRIMARY KEY"
+		}
+		cols = append(cols, col)
+	}
+
+	query := fmt.Sprintf("CREATE TABLE IF NOT EXISTS %s (%s)", quoteIdent(schema.Table), strings.Join(cols, ", "))
+	if _, err := d.db.Exec(query); err != nil {
+		return fmt.Errorf("model/postgres: create table: %w", err)
+	}
+
+	for _, f := range schema.Fields {
+		if f.Index && !f.IsKey {
+			idx := fmt.Sprintf("CREATE INDEX IF NOT EXISTS %s ON %s (%s)",
+				quoteIdent("idx_"+schema.Table+"_"+f.Column),
+				quoteIdent(schema.Table),
+				quoteIdent(f.Column))
+			if _, err := d.db.Exec(idx); err != nil {
+				return fmt.Errorf("model/postgres: create index: %w", err)
+			}
+		}
+	}
+
+	return nil
+}
+
+func (d *postgresModel) schema(v interface{}) (*model.Schema, error) {
+	t := model.ResolveType(v)
+	d.mu.RLock()
+	s, ok := d.types[t]
+	d.mu.RUnlock()
+	if !ok {
+		return nil, model.ErrNotRegistered
+	}
+	return s, nil
+}
+
+func (d *postgresModel) Create(ctx context.Context, v interface{}) error {
+	schema, err := d.schema(v)
+	if err != nil {
+		return err
+	}
+	fields := model.StructToMap(schema, v)
+	cols, placeholders, values := buildInsert(schema, fields)
+	query := fmt.Sprintf("INSERT INTO %s (%s) VALUES (%s)", quoteIdent(schema.Table), cols, placeholders)
+	_, err = d.db.ExecContext(ctx, query, values...)
+	if err != nil {
+		if strings.Contains(err.Error(), "duplicate key") || strings.Contains(err.Error(), "unique constraint") {
+			return model.ErrDuplicateKey
+		}
+		return fmt.Errorf("model/postgres: create: %w", err)
+	}
+	return nil
+}
+
+func (d *postgresModel) Read(ctx context.Context, key string, v interface{}) error {
+	schema, err := d.schema(v)
+	if err != nil {
+		return err
+	}
+	cols := columnList(schema)
+	query := fmt.Sprintf("SELECT %s FROM %s WHERE %s = $1", cols, quoteIdent(schema.Table), quoteIdent(schema.Key))
+	row := d.db.QueryRowContext(ctx, query, key)
+	fields, err := scanRow(schema, row)
+	if err != nil {
+		return err
+	}
+	model.MapToStruct(schema, fields, v)
+	return nil
+}
+
+func (d *postgresModel) Update(ctx context.Context, v interface{}) error {
+	schema, err := d.schema(v)
+	if err != nil {
+		return err
+	}
+	fields := model.StructToMap(schema, v)
+	key := model.KeyValue(schema, v)
+	setClauses, values := buildUpdate(schema, fields)
+	values = append(values, key)
+	paramIdx := len(values)
+	query := fmt.Sprintf("UPDATE %s SET %s WHERE %s = $%d",
+		quoteIdent(schema.Table), setClauses, quoteIdent(schema.Key), paramIdx)
+	result, err := d.db.ExecContext(ctx, query, values...)
+	if err != nil {
+		return fmt.Errorf("model/postgres: update: %w", err)
+	}
+	n, _ := result.RowsAffected()
+	if n == 0 {
+		return model.ErrNotFound
+	}
+	return nil
+}
+
+func (d *postgresModel) Delete(ctx context.Context, key string, v interface{}) error {
+	schema, err := d.schema(v)
+	if err != nil {
+		return err
+	}
+	query := fmt.Sprintf("DELETE FROM %s WHERE %s = $1", quoteIdent(schema.Table), quoteIdent(schema.Key))
+	result, err := d.db.ExecContext(ctx, query, key)
+	if err != nil {
+		return fmt.Errorf("model/postgres: delete: %w", err)
+	}
+	n, _ := result.RowsAffected()
+	if n == 0 {
+		return model.ErrNotFound
+	}
+	return nil
+}
+
+func (d *postgresModel) List(ctx context.Context, result interface{}, opts ...model.QueryOption) error {
+	rv := reflect.ValueOf(result)
+	if rv.Kind() != reflect.Pointer || rv.Elem().Kind() != reflect.Slice {
+		return fmt.Errorf("model/postgres: result must be a pointer to a slice")
+	}
+	sliceVal := rv.Elem()
+	elemType := sliceVal.Type().Elem()
+	structType := elemType
+	if structType.Kind() == reflect.Pointer {
+		structType = structType.Elem()
+	}
+
+	d.mu.RLock()
+	schema, ok := d.types[structType]
+	d.mu.RUnlock()
+	if !ok {
+		return model.ErrNotRegistered
+	}
+
+	q := model.ApplyQueryOptions(opts...)
+	cols := columnList(schema)
+
+	query := fmt.Sprintf("SELECT %s FROM %s", cols, quoteIdent(schema.Table))
+	var args []any
+	paramN := 1
+
+	if len(q.Filters) > 0 {
+		where, fArgs, _ := buildWhere(q.Filters, paramN)
+		query += " WHERE " + where
+		args = append(args, fArgs...)
+	}
+
+	if q.OrderBy != "" {
+		dir := "ASC"
+		if q.Desc {
+			dir = "DESC"
+		}
+		query += fmt.Sprintf(" ORDER BY %s %s", quoteIdent(q.OrderBy), dir)
+	}
+
+	if q.Limit > 0 {
+		query += fmt.Sprintf(" LIMIT %d", q.Limit)
+	}
+	if q.Offset > 0 {
+		query += fmt.Sprintf(" OFFSET %d", q.Offset)
+	}
+
+	rows, err := d.db.QueryContext(ctx, query, args...)
+	if err != nil {
+		return fmt.Errorf("model/postgres: list: %w", err)
+	}
+	defer rows.Close()
+
+	fieldMaps, err := scanRows(schema, rows)
+	if err != nil {
+		return err
+	}
+
+	results := reflect.MakeSlice(sliceVal.Type(), len(fieldMaps), len(fieldMaps))
+	for i, fields := range fieldMaps {
+		vp := reflect.New(structType)
+		model.MapToStruct(schema, fields, vp.Interface())
+		if elemType.Kind() == reflect.Pointer {
+			results.Index(i).Set(vp)
+		} else {
+			results.Index(i).Set(vp.Elem())
+		}
+	}
+	sliceVal.Set(results)
+	return nil
+}
+
+func (d *postgresModel) Count(ctx context.Context, v interface{}, opts ...model.QueryOption) (int64, error) {
+	schema, err := d.schema(v)
+	if err != nil {
+		return 0, err
+	}
+	q := model.ApplyQueryOptions(opts...)
+
+	query := fmt.Sprintf("SELECT COUNT(*) FROM %s", quoteIdent(schema.Table))
+	var args []any
+	paramN := 1
+
+	if len(q.Filters) > 0 {
+		where, fArgs, _ := buildWhere(q.Filters, paramN)
+		query += " WHERE " + where
+		args = append(args, fArgs...)
+	}
+
+	var count int64
+	err = d.db.QueryRowContext(ctx, query, args...).Scan(&count)
+	if err != nil {
+		return 0, fmt.Errorf("model/postgres: count: %w", err)
+	}
+	return count, nil
+}
+
+func (d *postgresModel) Close() error {
+	return d.db.Close()
+}
+
+func (d *postgresModel) String() string {
+	return "postgres"
+}
+
+// SQL helpers
+
+func quoteIdent(s string) string {
+	return `"` + strings.ReplaceAll(s, `"`, `""`) + `"`
+}
+
+func goTypeToPostgres(t reflect.Type) string {
+	switch t.Kind() {
+	case reflect.Int, reflect.Int64:
+		return "BIGINT"
+	case reflect.Int8, reflect.Int16, reflect.Int32:
+		return "INTEGER"
+	case reflect.Uint, reflect.Uint64:
+		return "BIGINT"
+	case reflect.Uint8, reflect.Uint16, reflect.Uint32:
+		return "INTEGER"
+	case reflect.Float32:
+		return "REAL"
+	case reflect.Float64:
+		return "DOUBLE PRECISION"
+	case reflect.Bool:
+		return "BOOLEAN"
+	default:
+		return "TEXT"
+	}
+}
+
+func buildInsert(schema *model.Schema, fields map[string]any) (string, string, []any) {
+	var cols []string
+	var placeholders []string
+	var values []any
+	i := 1
+	for _, f := range schema.Fields {
+		if v, ok := fields[f.Column]; ok {
+			cols = append(cols, quoteIdent(f.Column))
+			placeholders = append(placeholders, fmt.Sprintf("$%d", i))
+			values = append(values, v)
+			i++
+		}
+	}
+	return strings.Join(cols, ", "), strings.Join(placeholders, ", "), values
+}
+
+func buildUpdate(schema *model.Schema, fields map[string]any) (string, []any) {
+	var setClauses []string
+	var values []any
+	i := 1
+	for _, f := range schema.Fields {
+		if f.IsKey {
+			continue
+		}
+		if v, ok := fields[f.Column]; ok {
+			setClauses = append(setClauses, fmt.Sprintf("%s = $%d", quoteIdent(f.Column), i))
+			values = append(values, v)
+			i++
+		}
+	}
+	return strings.Join(setClauses, ", "), values
+}
+
+func buildWhere(filters []model.Filter, startParam int) (string, []any, int) {
+	var clauses []string
+	var args []any
+	n := startParam
+	for _, f := range filters {
+		clauses = append(clauses, fmt.Sprintf("%s %s $%d", quoteIdent(f.Field), f.Op, n))
+		args = append(args, f.Value)
+		n++
+	}
+	return strings.Join(clauses, " AND "), args, n
+}
+
+func columnList(schema *model.Schema) string {
+	var cols []string
+	for _, f := range schema.Fields {
+		cols = append(cols, quoteIdent(f.Column))
+	}
+	return strings.Join(cols, ", ")
+}
+
+func scanRow(schema *model.Schema, row *sql.Row) (map[string]any, error) {
+	ptrs := make([]any, len(schema.Fields))
+	for i, f := range schema.Fields {
+		ptrs[i] = newScanPtr(f.Type)
+	}
+	if err := row.Scan(ptrs...); err != nil {
+		if err == sql.ErrNoRows {
+			return nil, model.ErrNotFound
+		}
+		return nil, fmt.Errorf("model/postgres: scan: %w", err)
+	}
+	result := make(map[string]any, len(schema.Fields))
+	for i, f := range schema.Fields {
+		result[f.Column] = derefScanPtr(ptrs[i], f.Type)
+	}
+	return result, nil
+}
+
+func scanRows(schema *model.Schema, rows *sql.Rows) ([]map[string]any, error) {
+	var results []map[string]any
+	for rows.Next() {
+		ptrs := make([]any, len(schema.Fields))
+		for i, f := range schema.Fields {
+			ptrs[i] = newScanPtr(f.Type)
+		}
+		if err := rows.Scan(ptrs...); err != nil {
+			return nil, fmt.Errorf("model/postgres: scan row: %w", err)
+		}
+		row := make(map[string]any, len(schema.Fields))
+		for i, f := range schema.Fields {
+			row[f.Column] = derefScanPtr(ptrs[i], f.Type)
+		}
+		results = append(results, row)
+	}
+	return results, rows.Err()
+}
+
+func newScanPtr(t reflect.Type) any {
+	switch t.Kind() {
+	case reflect.String:
+		return new(string)
+	case reflect.Int, reflect.Int64:
+		return new(int64)
+	case reflect.Int32:
+		return new(int32)
+	case reflect.Float64:
+		return new(float64)
+	case reflect.Float32:
+		return new(float32)
+	case reflect.Bool:
+		return new(bool)
+	default:
+		return new(string)
+	}
+}
+
+func derefScanPtr(ptr any, t reflect.Type) any {
+	rv := reflect.ValueOf(ptr).Elem()
+	if rv.Type().ConvertibleTo(t) {
+		return rv.Convert(t).Interface()
+	}
+	return rv.Interface()
+}