dialect/sql/schema: support mariadb json fields on migration (#1011)

dialect/sql/schema/mysql.go

@@ -6,6 +6,7 @@ package schema
 
 import (
 	"context"
+	"database/sql/driver"
 	"fmt"
 	"math"
 	"sort"
@@ -102,6 +103,11 @@ func (d *MySQL) table(ctx context.Context, tx dialect.Tx, name string) (*Table,
 	for _, idx := range indexes {
 		t.AddIndex(idx.Name, idx.Unique, idx.columns)
 	}
+	if d.mariadb() {
+		if err := d.normalizeJSON(ctx, tx, t); err != nil {
+			return nil, err
+		}
+	}
 	return t, nil
 }
 
@@ -521,6 +527,57 @@ func (d *MySQL) alterColumns(table string, add, modify, drop []*Column) sql.Quer
 	return sql.Queries{b}
 }
 
+// normalizeJSON normalize MariaDB longtext columns to type JSON.
+func (d *MySQL) normalizeJSON(ctx context.Context, tx dialect.Tx, t *Table) error {
+	var (
+		names   []driver.Value
+		columns = make(map[string]*Column)
+	)
+	for _, c := range t.Columns {
+		if c.typ == "longtext" {
+			columns[c.Name] = c
+			names = append(names, c.Name)
+		}
+	}
+	if len(names) == 0 {
+		return nil
+	}
+	rows := &sql.Rows{}
+	query, args := sql.Select("CONSTRAINT_NAME", "CHECK_CLAUSE").
+		From(sql.Table("INFORMATION_SCHEMA.CHECK_CONSTRAINTS").Unquote()).
+		Where(sql.And(
+			sql.EQ("CONSTRAINT_SCHEMA", sql.Raw("(SELECT DATABASE())")),
+			sql.EQ("TABLE_NAME", t.Name),
+			sql.InValues("CONSTRAINT_NAME", names...),
+		)).
+		Query()
+	if err := tx.Query(ctx, query, args, rows); err != nil {
+		return fmt.Errorf("mysql: query table constraints %v", err)
+	}
+	// Call Close in cases of failures (Close is idempotent).
+	defer rows.Close()
+	for rows.Next() {
+		var name, check string
+		if err := rows.Scan(&name, &check); err != nil {
+			return fmt.Errorf("mysql: scan table constraints")
+		}
+		c, ok := columns[name]
+		if !ok || !strings.HasPrefix(check, "json_valid") {
+			continue
+		}
+		c.Type = field.TypeJSON
+	}
+	if err := rows.Err(); err != nil {
+		return err
+	}
+	return rows.Close()
+}
+
+// mariadb reports if the migration runs on MariaDB.
+func (d *MySQL) mariadb() bool {
+	return strings.Contains(d.version, "MariaDB")
+}
+
 // parseColumn returns column parts, size and signed-info from a MySQL type.
 func parseColumn(typ string) (parts []string, size int64, unsigned bool, err error) {
 	switch parts = strings.FieldsFunc(typ, func(r rune) bool {

dialect/sql/schema/mysql_test.go

@@ -150,7 +150,7 @@ func TestMySQL_Create(t *testing.T) {
 			},
 		},
 		{
-			name: "create new table with foreign key diabled",
+			name: "create new table with foreign key disabled",
 			options: []MigrateOption{
 				WithForeignKeys(false),
 			},
@@ -1032,6 +1032,44 @@ func TestMySQL_Create(t *testing.T) {
 				mock.ExpectCommit()
 			},
 		},
+		// MariaDB specific tests.
+		{
+			name: "mariadb/json columns",
+			tables: []*Table{
+				{
+					Name: "users",
+					Columns: []*Column{
+						{Name: "id", Type: field.TypeInt, Increment: true},
+						{Name: "name", Type: field.TypeString, Nullable: true},
+						{Name: "json", Type: field.TypeJSON, Nullable: true},
+						{Name: "longtext", Type: field.TypeString, Nullable: true, Size: math.MaxInt32},
+					},
+					PrimaryKey: []*Column{
+						{Name: "id", Type: field.TypeInt, Increment: true},
+					},
+				},
+			},
+			before: func(mock mysqlMock) {
+				mock.start("10.5.8-MariaDB-1:10.5.8+maria~focal")
+				mock.tableExists("users", true)
+				mock.ExpectQuery(escape("SELECT `column_name`, `column_type`, `is_nullable`, `column_key`, `column_default`, `extra`, `character_set_name`, `collation_name` FROM INFORMATION_SCHEMA.COLUMNS WHERE `TABLE_SCHEMA` = (SELECT DATABASE()) AND `TABLE_NAME` = ?")).
+					WithArgs("users").
+					WillReturnRows(sqlmock.NewRows([]string{"column_name", "column_type", "is_nullable", "column_key", "column_default", "extra", "character_set_name", "collation_name"}).
+						AddRow("id", "bigint(20)", "NO", "PRI", "NULL", "auto_increment", "", "").
+						AddRow("name", "varchar(255)", "YES", "YES", "NULL", "", "", "").
+						AddRow("json", "longtext", "YES", "YES", "NULL", "", "utf8mb4", "utf8mb4_bin").
+						AddRow("longtext", "longtext", "YES", "YES", "NULL", "", "utf8mb4", "utf8mb4_bin"))
+				mock.ExpectQuery(escape("SELECT `index_name`, `column_name`, `non_unique`, `seq_in_index` FROM INFORMATION_SCHEMA.STATISTICS WHERE `TABLE_SCHEMA` = (SELECT DATABASE()) AND `TABLE_NAME` = ? ORDER BY `index_name`, `seq_in_index`")).
+					WithArgs("users").
+					WillReturnRows(sqlmock.NewRows([]string{"index_name", "column_name", "non_unique", "seq_in_index"}).
+						AddRow("PRIMARY", "id", "0", "1"))
+				mock.ExpectQuery(escape("SELECT `CONSTRAINT_NAME`, `CHECK_CLAUSE` FROM INFORMATION_SCHEMA.CHECK_CONSTRAINTS WHERE `CONSTRAINT_SCHEMA` = (SELECT DATABASE()) AND `TABLE_NAME` = ? AND `CONSTRAINT_NAME` IN (?, ?)")).
+					WithArgs("users", "json", "longtext").
+					WillReturnRows(sqlmock.NewRows([]string{"CONSTRAINT_NAME", "CHECK_CLAUSE"}).
+						AddRow("json", "json_valid(`json`)"))
+				mock.ExpectCommit()
+			},
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {