From af18e1cf527644bd07d393fa5e7d11932009c52f Mon Sep 17 00:00:00 2001
From: Santinal Browns <60613674+santinalbrowns@users.noreply.github.com>
Date: Thu, 14 Aug 2025 11:47:17 +0200
Subject: [PATCH] fix: MySQL parameter binding compatibility with SQLAlchemy

- Convert MySQL '?' placeholders to named parameters (':p1', ':p2', etc.)
  for proper SQLAlchemy parameter binding
- Add MySQL type mapping support for Python type inference
- Fix SQL syntax error when using generated code with MySQL + SQLAlchemy

The generated code was using '?' placeholders in SQL but passing named
parameters as dictionaries, which caused MySQL syntax errors. This fix
ensures the SQL uses named parameters that match the parameter binding.

Fixes parameter binding issues for MySQL users of sqlc-gen-python.
---
 internal/gen.go        | 12 +++++++++-
 internal/mysql_type.go | 53 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 64 insertions(+), 1 deletion(-)
 create mode 100644 internal/mysql_type.go

diff --git a/internal/gen.go b/internal/gen.go
index 6e50fae..e51c626 100644
--- a/internal/gen.go
+++ b/internal/gen.go
@@ -193,8 +193,10 @@ func pyInnerType(req *plugin.GenerateRequest, col *plugin.Column) string {
 	switch req.Settings.Engine {
 	case "postgresql":
 		return postgresType(req, col)
+	case "mysql":
+		return mysqlType(req, col)
 	default:
-		log.Println("unsupported engine type")
+		log.Printf("unsupported engine type: %s\n", req.Settings.Engine)
 		return "Any"
 	}
 }
@@ -360,6 +362,14 @@ func sqlalchemySQL(s, engine string) string {
 	if engine == "postgresql" {
 		return postgresPlaceholderRegexp.ReplaceAllString(s, ":p$1")
 	}
+	if engine == "mysql" {
+		// Convert MySQL ? placeholders to named parameters for SQLAlchemy compatibility
+		i := 1
+		for strings.Contains(s, "?") {
+			s = strings.Replace(s, "?", fmt.Sprintf(":p%d", i), 1)
+			i++
+		}
+	}
 	return s
 }
 
diff --git a/internal/mysql_type.go b/internal/mysql_type.go
new file mode 100644
index 0000000..0b2ff20
--- /dev/null
+++ b/internal/mysql_type.go
@@ -0,0 +1,53 @@
+package python
+
+import (
+	"log"
+
+	"github.com/sqlc-dev/plugin-sdk-go/plugin"
+	"github.com/sqlc-dev/plugin-sdk-go/sdk"
+)
+
+func mysqlType(req *plugin.GenerateRequest, col *plugin.Column) string {
+	columnType := sdk.DataType(col.Type)
+
+	switch columnType {
+	case "tinyint", "smallint", "mediumint", "int", "integer", "bigint":
+		return "int"
+	case "float", "double", "real":
+		return "float"
+	case "decimal", "numeric":
+		return "decimal.Decimal"
+	case "bit", "boolean", "bool":
+		return "bool"
+	case "json":
+		return "Any"
+	case "binary", "varbinary", "blob", "tinyblob", "mediumblob", "longblob":
+		return "memoryview"
+	case "date":
+		return "datetime.date"
+	case "time":
+		return "datetime.time"
+	case "datetime", "timestamp":
+		return "datetime.datetime"
+	case "char", "varchar", "text", "tinytext", "mediumtext", "longtext":
+		return "str"
+	case "enum", "set":
+		return "str"
+	default:
+		for _, schema := range req.Catalog.Schemas {
+			if schema.Name == "information_schema" || schema.Name == "mysql" {
+				continue
+			}
+			for _, enum := range schema.Enums {
+				if columnType == enum.Name {
+					if schema.Name == req.Catalog.DefaultSchema {
+						return "models." + modelName(enum.Name, req.Settings)
+					}
+					return "models." + modelName(schema.Name+"_"+enum.Name, req.Settings)
+				}
+			}
+		}
+		log.Printf("unknown MySQL type: %s\n", columnType)
+		return "Any"
+	}
+}