fix: default value with typecast and tests

migrator.go

@@ -477,7 +477,7 @@ func (m Migrator) ColumnTypes(value interface{}) (columnTypes []gorm.ColumnType,
 			}
 
 			if column.DefaultValueValue.Valid {
-				column.DefaultValueValue.String = regexp.MustCompile(`'?(.*\b|)'?:+[\w\s]+$`).ReplaceAllString(column.DefaultValueValue.String, "$1")
+				column.DefaultValueValue.String = parseDefaultValueValue(column.DefaultValueValue.String)
 			}
 
 			if datetimePrecision.Valid {
@@ -783,3 +783,7 @@ func (m Migrator) RenameColumn(dst interface{}, oldName, field string) error {
 	m.resetPreparedStmts()
 	return nil
 }
+
+func parseDefaultValueValue(defaultValue string) string {
+	return regexp.MustCompile(`^(.*?)(?:::.*)?$`).ReplaceAllString(defaultValue, "$1")
+}

migrator_test.go

@@ -0,0 +1,102 @@
+package postgres
+
+import "testing"
+
+func Test_parseDefaultValueValue(t *testing.T) {
+	type args struct {
+		defaultValue string
+	}
+	tests := []struct {
+		name string
+		args args
+		want string
+	}{
+		{
+			name: "it should works with number without colons",
+			args: args{defaultValue: "0"},
+			want: "0",
+		},
+		{
+			name: "it should works with number and two colons",
+			args: args{defaultValue: "0::int8"},
+			want: "0",
+		},
+		{
+			name: "it should works with number and three colons",
+			args: args{defaultValue: "0:::int8"},
+			want: "0",
+		},
+		{
+			name: "it should works with empty string without colons",
+			args: args{defaultValue: "''"},
+			want: "''",
+		},
+		{
+			name: "it should works with empty string with two colons",
+			args: args{defaultValue: "''::character varying"},
+			want: "''",
+		},
+		{
+			name: "it should works with empty string with three colons",
+			args: args{defaultValue: "'':::character varying"},
+			want: "''",
+		},
+		{
+			name: "it should works with string without colons",
+			args: args{defaultValue: "'field'"},
+			want: "'field'",
+		},
+		{
+			name: "it should works with string with two colons",
+			args: args{defaultValue: "'field'::character varying"},
+			want: "'field'",
+		},
+		{
+			name: "it should works with string with three colons",
+			args: args{defaultValue: "'field':::character varying"},
+			want: "'field'",
+		},
+		{
+			name: "it should works with value with two colons",
+			args: args{defaultValue: "field"},
+			want: "field",
+		},
+		{
+			name: "it should works with value without colons",
+			args: args{defaultValue: "field::character varying"},
+			want: "field",
+		},
+		{
+			name: "it should works with value with three colons",
+			args: args{defaultValue: "field:::character varying"},
+			want: "field",
+		},
+		{
+			name: "it should works with function without colons",
+			args: args{defaultValue: "now()"},
+			want: "now()",
+		},
+		{
+			name: "it should works with function with two colons",
+			args: args{defaultValue: "now()::timestamp without time zone"},
+			want: "now()",
+		},
+		{
+			name: "it should works with json without colons",
+			args: args{defaultValue: "{}"},
+			want: "{}",
+		},
+		{
+			name: "it should works with json with two colons",
+			args: args{defaultValue: "{}::jsonb"},
+			want: "{}",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := parseDefaultValueValue(tt.args.defaultValue); got != tt.want {
+				t.Errorf("parseDefaultValueValue() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}