Iterx put to separate file
This commit is contained in:
Michał Matczuk
235
gocqlx.go
235
gocqlx.go
@@ -16,241 +16,6 @@ import (
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// use on a type.
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// use on a type.
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var DefaultMapper = reflectx.NewMapperFunc("db", strings.ToLower)
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var DefaultMapper = reflectx.NewMapperFunc("db", strings.ToLower)
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// Get is a convenience function for creating iterator and calling Get on it.
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func Get(dest interface{}, q *gocql.Query) error {
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return Iter(q).Get(dest)
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}
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// Select is a convenience function for creating iterator and calling Select on it.
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func Select(dest interface{}, q *gocql.Query) error {
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return Iter(q).Select(dest)
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}
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// Iterx is a wrapper around gocql.Iter which adds struct scanning capabilities.
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type Iterx struct {
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*gocql.Iter
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query *gocql.Query
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err error
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unsafe bool
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Mapper *reflectx.Mapper
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// these fields cache memory use for a rows during iteration w/ structScan
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started bool
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fields [][]int
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values []interface{}
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}
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// Iter creates a new Iterx from gocql.Query using a default mapper.
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func Iter(q *gocql.Query) *Iterx {
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return &Iterx{
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Iter: q.Iter(),
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query: q,
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Mapper: DefaultMapper,
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}
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}
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// Get scans first row into a destination and closes the iterator. If the
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// destination type is a Struct, then StructScan will be used. If the
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// destination is some other type, then the row must only have one column which
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// can scan into that type.
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func (iter *Iterx) Get(dest interface{}) error {
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if iter.query == nil {
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return errors.New("using released query")
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}
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if err := iter.scanAny(dest, false); err != nil {
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iter.err = err
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}
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iter.Close()
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iter.ReleaseQuery()
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return iter.err
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}
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func (iter *Iterx) scanAny(dest interface{}, structOnly bool) error {
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v := reflect.ValueOf(dest)
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if v.Kind() != reflect.Ptr {
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return errors.New("must pass a pointer, not a value, to StructScan destination")
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}
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if v.IsNil() {
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return errors.New("nil pointer passed to StructScan destination")
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}
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base := reflectx.Deref(v.Type())
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scannable := isScannable(base)
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if structOnly && scannable {
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return structOnlyError(base)
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}
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if scannable && len(iter.Columns()) > 1 {
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return fmt.Errorf("scannable dest type %s with >1 columns (%d) in result", base.Kind(), len(iter.Columns()))
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}
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if !scannable {
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iter.StructScan(dest)
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} else {
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iter.Scan(dest)
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}
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return iter.err
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}
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// Select scans all rows into a destination, which must be a slice of any type
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// and closes the iterator. If the destination slice type is a Struct, then
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// StructScan will be used on each row. If the destination is some other type,
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// then each row must only have one column which can scan into that type.
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func (iter *Iterx) Select(dest interface{}) error {
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if iter.query == nil {
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return errors.New("using released query")
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}
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if err := iter.scanAll(dest, false); err != nil {
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iter.err = err
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}
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iter.Close()
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iter.ReleaseQuery()
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return iter.err
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}
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func (iter *Iterx) scanAll(dest interface{}, structOnly bool) error {
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var v, vp reflect.Value
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value := reflect.ValueOf(dest)
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// json.Unmarshal returns errors for these
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if value.Kind() != reflect.Ptr {
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return errors.New("must pass a pointer, not a value, to StructScan destination")
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}
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if value.IsNil() {
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return errors.New("nil pointer passed to StructScan destination")
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}
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direct := reflect.Indirect(value)
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slice, err := baseType(value.Type(), reflect.Slice)
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if err != nil {
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return err
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}
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isPtr := slice.Elem().Kind() == reflect.Ptr
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base := reflectx.Deref(slice.Elem())
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scannable := isScannable(base)
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if structOnly && scannable {
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return structOnlyError(base)
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}
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// if it's a base type make sure it only has 1 column; if not return an error
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if scannable && len(iter.Columns()) > 1 {
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return fmt.Errorf("non-struct dest type %s with >1 columns (%d)", base.Kind(), len(iter.Columns()))
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}
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if !scannable {
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for {
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// create a new struct type (which returns PtrTo) and indirect it
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vp = reflect.New(base)
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v = reflect.Indirect(vp)
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// scan into the struct field pointers and append to our results
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if ok := iter.StructScan(vp.Interface()); !ok {
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break
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}
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if isPtr {
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direct.Set(reflect.Append(direct, vp))
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} else {
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direct.Set(reflect.Append(direct, v))
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}
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}
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} else {
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for {
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vp = reflect.New(base)
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if ok := iter.Scan(vp.Interface()); !ok {
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break
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}
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// append
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if isPtr {
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direct.Set(reflect.Append(direct, vp))
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} else {
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direct.Set(reflect.Append(direct, reflect.Indirect(vp)))
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}
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}
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}
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return iter.err
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}
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// StructScan is like gocql.Scan, but scans a single row into a single Struct.
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// Use this and iterate manually when the memory load of Select() might be
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// prohibitive. StructScan caches the reflect work of matching up column
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// positions to fields to avoid that overhead per scan, which means it is not
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// safe to run StructScan on the same Iterx instance with different struct
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// types.
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func (iter *Iterx) StructScan(dest interface{}) bool {
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if iter.query == nil {
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iter.err = errors.New("using released query")
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return false
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}
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v := reflect.ValueOf(dest)
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if v.Kind() != reflect.Ptr {
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iter.err = errors.New("must pass a pointer, not a value, to StructScan destination")
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return false
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}
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if !iter.started {
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columns := columnNames(iter.Iter.Columns())
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m := iter.Mapper
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iter.fields = m.TraversalsByName(v.Type(), columns)
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// if we are not unsafe and are missing fields, return an error
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if f, err := missingFields(iter.fields); err != nil && !iter.unsafe {
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iter.err = fmt.Errorf("missing destination name %s in %T", columns[f], dest)
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return false
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}
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iter.values = make([]interface{}, len(columns))
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iter.started = true
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}
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err := fieldsByTraversal(v, iter.fields, iter.values, true)
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if err != nil {
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iter.err = err
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return false
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}
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// scan into the struct field pointers and append to our results
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return iter.Iter.Scan(iter.values...)
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}
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func columnNames(ci []gocql.ColumnInfo) []string {
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r := make([]string, len(ci))
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for i, column := range ci {
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r[i] = column.Name
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}
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return r
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}
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// Close closes the iterator and returns any errors that happened during
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// the query or the iteration.
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func (iter *Iterx) Close() error {
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err := iter.Iter.Close()
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if err != nil && iter.err == nil {
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iter.err = err
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}
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return iter.err
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}
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// ReleaseQuery releases underling query back into a pool of queries. Note that
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// the iterator needs to be closed first.
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func (iter *Iterx) ReleaseQuery() {
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if iter.query != nil {
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iter.query.Release()
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iter.query = nil
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}
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}
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// structOnlyError returns an error appropriate for type when a non-scannable
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// structOnlyError returns an error appropriate for type when a non-scannable
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// struct is expected but something else is given
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// struct is expected but something else is given
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func structOnlyError(t reflect.Type) error {
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func structOnlyError(t reflect.Type) error {
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245
iterx.go
Normal file
245
iterx.go
Normal file
@@ -0,0 +1,245 @@
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package gocqlx
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import (
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"errors"
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"fmt"
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"reflect"
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"github.com/gocql/gocql"
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"github.com/jmoiron/sqlx/reflectx"
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)
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// Get is a convenience function for creating iterator and calling Get on it.
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func Get(dest interface{}, q *gocql.Query) error {
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return Iter(q).Get(dest)
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}
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// Select is a convenience function for creating iterator and calling Select on it.
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func Select(dest interface{}, q *gocql.Query) error {
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return Iter(q).Select(dest)
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}
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// Iterx is a wrapper around gocql.Iter which adds struct scanning capabilities.
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type Iterx struct {
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*gocql.Iter
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query *gocql.Query
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err error
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unsafe bool
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Mapper *reflectx.Mapper
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// these fields cache memory use for a rows during iteration w/ structScan
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started bool
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fields [][]int
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values []interface{}
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}
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// Iter creates a new Iterx from gocql.Query using a default mapper.
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func Iter(q *gocql.Query) *Iterx {
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return &Iterx{
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Iter: q.Iter(),
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query: q,
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Mapper: DefaultMapper,
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}
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}
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// Get scans first row into a destination and closes the iterator. If the
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// destination type is a Struct, then StructScan will be used. If the
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// destination is some other type, then the row must only have one column which
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// can scan into that type.
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func (iter *Iterx) Get(dest interface{}) error {
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if iter.query == nil {
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return errors.New("using released query")
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}
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if err := iter.scanAny(dest, false); err != nil {
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iter.err = err
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}
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iter.Close()
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iter.ReleaseQuery()
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return iter.err
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}
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func (iter *Iterx) scanAny(dest interface{}, structOnly bool) error {
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v := reflect.ValueOf(dest)
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if v.Kind() != reflect.Ptr {
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return errors.New("must pass a pointer, not a value, to StructScan destination")
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}
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if v.IsNil() {
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return errors.New("nil pointer passed to StructScan destination")
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}
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base := reflectx.Deref(v.Type())
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scannable := isScannable(base)
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if structOnly && scannable {
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return structOnlyError(base)
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}
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if scannable && len(iter.Columns()) > 1 {
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return fmt.Errorf("scannable dest type %s with >1 columns (%d) in result", base.Kind(), len(iter.Columns()))
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}
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if !scannable {
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iter.StructScan(dest)
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} else {
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iter.Scan(dest)
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}
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return iter.err
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}
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// Select scans all rows into a destination, which must be a slice of any type
|
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|
// and closes the iterator. If the destination slice type is a Struct, then
|
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|
// StructScan will be used on each row. If the destination is some other type,
|
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|
// then each row must only have one column which can scan into that type.
|
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func (iter *Iterx) Select(dest interface{}) error {
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if iter.query == nil {
|
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return errors.New("using released query")
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}
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if err := iter.scanAll(dest, false); err != nil {
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iter.err = err
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}
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iter.Close()
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iter.ReleaseQuery()
|
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|
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return iter.err
|
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}
|
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|
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func (iter *Iterx) scanAll(dest interface{}, structOnly bool) error {
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var v, vp reflect.Value
|
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|
|
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value := reflect.ValueOf(dest)
|
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|
|
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|
// json.Unmarshal returns errors for these
|
||||||
|
if value.Kind() != reflect.Ptr {
|
||||||
|
return errors.New("must pass a pointer, not a value, to StructScan destination")
|
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|
}
|
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|
if value.IsNil() {
|
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return errors.New("nil pointer passed to StructScan destination")
|
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|
}
|
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direct := reflect.Indirect(value)
|
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|
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slice, err := baseType(value.Type(), reflect.Slice)
|
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|
if err != nil {
|
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|
return err
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|
}
|
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|
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|
isPtr := slice.Elem().Kind() == reflect.Ptr
|
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base := reflectx.Deref(slice.Elem())
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scannable := isScannable(base)
|
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if structOnly && scannable {
|
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return structOnlyError(base)
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|
}
|
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|
|
||||||
|
// if it's a base type make sure it only has 1 column; if not return an error
|
||||||
|
if scannable && len(iter.Columns()) > 1 {
|
||||||
|
return fmt.Errorf("non-struct dest type %s with >1 columns (%d)", base.Kind(), len(iter.Columns()))
|
||||||
|
}
|
||||||
|
|
||||||
|
if !scannable {
|
||||||
|
for {
|
||||||
|
// create a new struct type (which returns PtrTo) and indirect it
|
||||||
|
vp = reflect.New(base)
|
||||||
|
v = reflect.Indirect(vp)
|
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|
// scan into the struct field pointers and append to our results
|
||||||
|
if ok := iter.StructScan(vp.Interface()); !ok {
|
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|
break
|
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|
}
|
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|
|
||||||
|
if isPtr {
|
||||||
|
direct.Set(reflect.Append(direct, vp))
|
||||||
|
} else {
|
||||||
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direct.Set(reflect.Append(direct, v))
|
||||||
|
}
|
||||||
|
}
|
||||||
|
} else {
|
||||||
|
for {
|
||||||
|
vp = reflect.New(base)
|
||||||
|
if ok := iter.Scan(vp.Interface()); !ok {
|
||||||
|
break
|
||||||
|
}
|
||||||
|
|
||||||
|
// append
|
||||||
|
if isPtr {
|
||||||
|
direct.Set(reflect.Append(direct, vp))
|
||||||
|
} else {
|
||||||
|
direct.Set(reflect.Append(direct, reflect.Indirect(vp)))
|
||||||
|
}
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
return iter.err
|
||||||
|
}
|
||||||
|
|
||||||
|
// StructScan is like gocql.Scan, but scans a single row into a single Struct.
|
||||||
|
// Use this and iterate manually when the memory load of Select() might be
|
||||||
|
// prohibitive. StructScan caches the reflect work of matching up column
|
||||||
|
// positions to fields to avoid that overhead per scan, which means it is not
|
||||||
|
// safe to run StructScan on the same Iterx instance with different struct
|
||||||
|
// types.
|
||||||
|
func (iter *Iterx) StructScan(dest interface{}) bool {
|
||||||
|
if iter.query == nil {
|
||||||
|
iter.err = errors.New("using released query")
|
||||||
|
return false
|
||||||
|
}
|
||||||
|
|
||||||
|
v := reflect.ValueOf(dest)
|
||||||
|
if v.Kind() != reflect.Ptr {
|
||||||
|
iter.err = errors.New("must pass a pointer, not a value, to StructScan destination")
|
||||||
|
return false
|
||||||
|
}
|
||||||
|
|
||||||
|
if !iter.started {
|
||||||
|
columns := columnNames(iter.Iter.Columns())
|
||||||
|
m := iter.Mapper
|
||||||
|
|
||||||
|
iter.fields = m.TraversalsByName(v.Type(), columns)
|
||||||
|
// if we are not unsafe and are missing fields, return an error
|
||||||
|
if f, err := missingFields(iter.fields); err != nil && !iter.unsafe {
|
||||||
|
iter.err = fmt.Errorf("missing destination name %s in %T", columns[f], dest)
|
||||||
|
return false
|
||||||
|
}
|
||||||
|
iter.values = make([]interface{}, len(columns))
|
||||||
|
iter.started = true
|
||||||
|
}
|
||||||
|
|
||||||
|
err := fieldsByTraversal(v, iter.fields, iter.values, true)
|
||||||
|
if err != nil {
|
||||||
|
iter.err = err
|
||||||
|
return false
|
||||||
|
}
|
||||||
|
// scan into the struct field pointers and append to our results
|
||||||
|
return iter.Iter.Scan(iter.values...)
|
||||||
|
}
|
||||||
|
|
||||||
|
func columnNames(ci []gocql.ColumnInfo) []string {
|
||||||
|
r := make([]string, len(ci))
|
||||||
|
for i, column := range ci {
|
||||||
|
r[i] = column.Name
|
||||||
|
}
|
||||||
|
return r
|
||||||
|
}
|
||||||
|
|
||||||
|
// Close closes the iterator and returns any errors that happened during
|
||||||
|
// the query or the iteration.
|
||||||
|
func (iter *Iterx) Close() error {
|
||||||
|
err := iter.Iter.Close()
|
||||||
|
if err != nil && iter.err == nil {
|
||||||
|
iter.err = err
|
||||||
|
}
|
||||||
|
return iter.err
|
||||||
|
}
|
||||||
|
|
||||||
|
// ReleaseQuery releases underling query back into a pool of queries. Note that
|
||||||
|
// the iterator needs to be closed first.
|
||||||
|
func (iter *Iterx) ReleaseQuery() {
|
||||||
|
if iter.query != nil {
|
||||||
|
iter.query.Release()
|
||||||
|
iter.query = nil
|
||||||
|
}
|
||||||
|
}
|
||||||
Reference in New Issue
Block a user