Added PgGoConnection interface. Added basic pgComment and test.

Author: vvuwei

database/pg.go

@@ -9,6 +9,14 @@ import (
 	"github.com/pkg/errors"
 )
 
+type PgGoConnection interface {
+	DB() PgDB
+}
+
+type PgDB interface {
+	ExecContext(c context.Context, query interface{}, params ...interface{}) (pg.Result, error)
+}
+
 // PgGo -
 type PgGo struct {
 	conn *pg.DB

database/pgComment.go

@@ -0,0 +1,65 @@
+package database
+
+import (
+	"context"
+	"github.com/dipdup-net/go-lib/hasura"
+	"github.com/go-pg/pg/v10"
+	"github.com/pkg/errors"
+	"reflect"
+	"strings"
+)
+
+func makeComments(ctx context.Context, conn *PgGo, model interface{}) error {
+	typ := reflect.TypeOf(model)
+
+	// 1. go through fields
+	// 2. if tableName field -
+	//		2.1 read value from pg tab, if not exist from model type name with snake case convertion - remember as tableName
+	// 		2.2 read value from pg-comment tag, if not exist continue
+	//		2.3 set comment with SQL statement
+	// 3. other
+	//		3.1 read comment from pg-comment, it not exist continue
+	// 		3.2 read pg tag first value if it exist, if not - then snake case name of field and set as columnName
+	// 		3.3 set comment with SQL statement
+	for i := 0; i < typ.NumField(); i++ {
+		fieldType := typ.Field(i)
+		pgTag, ok := fieldType.Tag.Lookup("pg")
+		if !ok {
+			continue
+		}
+
+		tags := strings.Split(pgTag, ",")
+
+		var name string
+		for i := range tags {
+			if i == 0 {
+				if name == "" {
+					name = hasura.ToSnakeCase(fieldType.Name)
+				} else {
+					name = tags[i]
+				}
+				continue
+			}
+
+			parts := strings.Split(tags[i], ":")
+			if parts[0] == "comment" {
+				if len(parts) != 2 {
+					return errors.Errorf("invalid comments format: %s", pgTag)
+				}
+				if fieldType.Name == "tableName" {
+					// typ.Name() to
+					if _, err := conn.DB().ExecContext(ctx, `COMMENT ON TABLE ? IS ?`, pg.Safe(typ.Name()), parts[1]); err != nil {
+						return err
+					}
+				} else {
+					if _, err := conn.DB().ExecContext(ctx, `COMMENT ON COLUMN ?.? IS ?`, pg.Safe(typ.Name()), pg.Safe(name), parts[1]); err != nil {
+						return err
+					}
+				}
+				continue
+			}
+		}
+	}
+
+	return nil
+}

database/pgComment_test.go

@@ -0,0 +1 @@
+package database