GolangのORMパッケージ「gorp」でSQLのプレースホルダーを使用しIN句を書きたい

    args := make([]interface{}, len(fileIds))
    quarks := make([]string, len(fileIds))
    for i, fileId := range fileIds {
        args[i] = fileId
        quarks[i] = "?"
    }

    var apps []*App
    _, err := dbMap.Select(&apps, fmt.Sprintf("SELECT * FROM app WHERE file_id in (%s) ORDER BY id DESC", strings.Join(quarks, ",")), args...)
    if err != nil {
        return nil, err
    }

type DbMap struct {

    // Db handle to use with this map
    Db  *sql.DB

    // Dialect implementation to use with this map
    Dialect Dialect

    TypeConverter TypeConverter

    // ExpandSlices when enabled will convert slice arguments in mappers into flat
    // values. It will modify the query, adding more placeholders, and the mapper,
    // adding each item of the slice as a new unique entry in the mapper. For
    // example, given the scenario bellow:
    //
    //     dbmap.Select(&output, "SELECT 1 FROM example WHERE id IN (:IDs)", map[string]interface{}{
    //       "IDs": []int64{1, 2, 3},
    //     })
    //
    // The executed query would be:
    //
    //     SELECT 1 FROM example WHERE id IN (:IDs0,:IDs1,:IDs2)
    //
    // With the mapper:
    //
    //     map[string]interface{}{
    //       "IDs":  []int64{1, 2, 3},
    //       "IDs0": int64(1),
    //       "IDs1": int64(2),
    //       "IDs2": int64(3),
    //     }
    //
    // It is also flexible for custom slice types. The value just need to
    // implement stringer or numberer interfaces.
    //
    //     type CustomValue string
    //
    //     const (
    //       CustomValueHey CustomValue = "hey"
    //       CustomValueOh  CustomValue = "oh"
    //     )
    //
    //     type CustomValues []CustomValue
    //
    //     func (c CustomValues) ToStringSlice() []string {
    //       values := make([]string, len(c))
    //       for i := range c {
    //         values[i] = string(c[i])
    //       }
    //       return values
    //     }
    //
    //     func query() {
    //       // ...
    //       result, err := dbmap.Select(&output, "SELECT 1 FROM example WHERE value IN (:Values)", map[string]interface{}{
    //         "Values": CustomValues([]CustomValue{CustomValueHey}),
    //       })
    //       // ...
    //     }
    ExpandSliceArgs bool
    // contains filtered or unexported fields
}