Golang IndexDescriptor.Unique方法代码示例

// SchemaFromModel allows the easy construction of a TableDescriptor from a Go
// struct. Columns are created for each exported field in the struct. The "db"
// struct tag is used to control the mapping of field name to column name and
// to indicate exported fields which should be skipped.
//
//   type User struct {
//     ID      int
//     Name    string `db:"old_name"`
//     Ignored int    `db:"-"`
//   }
//
// Indexes are specified using the "roach" struct tag declaration.
//
//   type User struct {
//     ID   int    `roach:"primary key"`
//     Name string `db:"old_name" roach:"index"`
//   }
//
// The following "roach" options are supported:
//
//   "primary key [(columns...)]" - creates a unique index on <columns> and
//   marks it as the primary key for the table. If <columns> is not specified
//   it defaults to the name of the column the option is associated with.
//
//   "index" [(columns...)]" - creates an index on <columns>.
//
//   "unique index" [(columns...)]" - creates a unique index on <columns>.
func SchemaFromModel(obj interface{}) (structured.TableDescriptor, error) {
	desc := structured.TableDescriptor{}
	m, err := getDBFields(deref(reflect.TypeOf(obj)))
	if err != nil {
		return desc, err
	}

	desc.Name = strings.ToLower(reflect.TypeOf(obj).Name())

	// Create the columns for the table.
	for name, sf := range m {
		colType := structured.ColumnType{}

		// TODO(pmattis): The mapping from Go-type Kind to column-type Kind is
		// likely not complete or correct, but this is probably going away pretty
		// soon with the move to SQL.
		switch sf.Type.Kind() {
		case reflect.Bool, reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32,
			reflect.Int64, reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32,
			reflect.Uint64, reflect.Uintptr:
			colType.Kind = structured.ColumnType_INT

		case reflect.Float32, reflect.Float64:
			colType.Kind = structured.ColumnType_FLOAT

		case reflect.String:
			colType.Kind = structured.ColumnType_TEXT
		}

		col := structured.ColumnDescriptor{
			Name: name,
			Type: colType,
		}
		desc.Columns = append(desc.Columns, col)
	}

	// Create the indexes for the table.
	for name, f := range m {
		tag := f.Tag.Get("roach")
		if tag == "" {
			continue
		}
		for _, opt := range strings.Split(tag, ";") {
			match := schemaOptRE.FindStringSubmatch(opt)
			if match == nil {
				return desc, fmt.Errorf("invalid schema option: %s", opt)
			}
			cmd := match[1]
			var params []string
			if len(match[2]) > 0 {
				params = strings.Split(match[2], ",")
			} else {
				params = []string{name}
			}
			var index structured.IndexDescriptor
			switch strings.ToLower(cmd) {
			case "primary key":
				index.Name = structured.PrimaryKeyIndexName
				index.Unique = true
			case "unique index":
				index.Name = strings.Join(params, ":")
				index.Unique = true
			case "index":
				index.Name = strings.Join(params, ":")
			}
			index.ColumnNames = params
			desc.Indexes = append(desc.Indexes, index)
		}
	}

	// Normalize the column and index order.
	sort.Sort(columnsByName(desc.Columns))
	sort.Sort(indexesByName(desc.Indexes))
//.........这里部分代码省略.........