docstore/memdocstore: #3508 allow nested slices query

Author: eqinox76

docstore/memdocstore/codec.go

@@ -104,7 +104,7 @@ func decodeDoc(m storedDoc, ddoc driver.Document, fps [][]string) error {
 		// (We don't need the key field because ddoc must already have it.)
 		m2 = map[string]interface{}{}
 		for _, fp := range fps {
-			val, err := getAtFieldPath(m, fp)
+			val, err := getAtFieldPath(m, fp, false)
 			if err != nil {
 				if gcerrors.Code(err) == gcerrors.NotFound {
 					continue

docstore/memdocstore/mem.go

@@ -68,6 +68,12 @@ type Options struct {
 	// When the collection is closed, its contents are saved to the file.
 	Filename string
 
+	// AllowNestedSlicesQuery allows querying with nested slices.
+	// This makes the memdocstore more compatible with MongoDB,
+	// but other providers may not support this feature.
+	// See https://github.com/google/go-cloud/pull/3511 for more details.
+	AllowNestedSlicesQuery bool
+
 	// Call this function when the collection is closed.
 	// For internal use only.
 	onClose func()
@@ -399,16 +405,34 @@ func (c *collection) checkRevision(arg driver.Document, current storedDoc) error
 
 // getAtFieldPath gets the value of m at fp. It returns an error if fp is invalid
 // (see getParentMap).
-func getAtFieldPath(m map[string]interface{}, fp []string) (interface{}, error) {
-	m2, err := getParentMap(m, fp, false)
-	if err != nil {
-		return nil, err
+func getAtFieldPath(m map[string]interface{}, fp []string, nested bool) (result interface{}, err error) {
+
+	var get func(m interface{}, name string) interface{}
+	get = func(m interface{}, name string) interface{} {
+		switch concrete := m.(type) {
+		case map[string]interface{}:
+			return concrete[name]
+		case []interface{}:
+			if !nested {
+				return nil
+			}
+			result := []interface{}{}
+			for _, e := range concrete {
+				result = append(result, get(e, name))
+			}
+			return result
+		}
+		return nil
 	}
-	v, ok := m2[fp[len(fp)-1]]
-	if ok {
-		return v, nil
+	result = m
+	for _, k := range fp {
+		next := get(result, k)
+		if next == nil {
+			return nil, gcerr.Newf(gcerr.NotFound, nil, "field %s not found", strings.Join(fp, "."))
+		}
+		result = next
 	}
-	return nil, gcerr.Newf(gcerr.NotFound, nil, "field %s not found", fp)
+	return result, nil
 }
 
 // setAtFieldPath sets m's value at fp to val. It creates intermediate maps as
@@ -422,14 +446,6 @@ func setAtFieldPath(m map[string]interface{}, fp []string, val interface{}) erro
 	return nil
 }
 
-// Delete the value from m at the given field path, if it exists.
-func deleteAtFieldPath(m map[string]interface{}, fp []string) {
-	m2, _ := getParentMap(m, fp, false) // ignore error
-	if m2 != nil {
-		delete(m2, fp[len(fp)-1])
-	}
-}
-
 // getParentMap returns the map that directly contains the given field path;
 // that is, the value of m at the field path that excludes the last component
 // of fp. If a non-map is encountered along the way, an InvalidArgument error is

docstore/memdocstore/mem_test.go

@@ -16,6 +16,7 @@ package memdocstore
 
 import (
 	"context"
+	"io"
 	"os"
 	"path/filepath"
 	"testing"
@@ -129,6 +130,49 @@ func TestUpdateAtomic(t *testing.T) {
 	}
 }
 
+func TestQueryNested(t *testing.T) {
+	ctx := context.Background()
+
+	count := func(iter *docstore.DocumentIterator) (c int) {
+		doc := docmap{}
+		for {
+			if err := iter.Next(ctx, doc); err != nil {
+				if err == io.EOF {
+					break
+				}
+				t.Fatal(err)
+			}
+			c++
+		}
+		return c
+	}
+
+	dc, err := newCollection(drivertest.KeyField, nil, &Options{AllowNestedSlicesQuery: true})
+	if err != nil {
+		t.Fatal(err)
+	}
+	coll := docstore.NewCollection(dc)
+	defer coll.Close()
+
+	doc := docmap{drivertest.KeyField: "TestQueryNested",
+		"list":             []any{docmap{"a": "A"}},
+		"map":              docmap{"b": "B"},
+		dc.RevisionField(): nil,
+	}
+	if err := coll.Put(ctx, doc); err != nil {
+		t.Fatal(err)
+	}
+
+	got := count(coll.Query().Where("list.a", "=", "A").Get(ctx))
+	if got != 1 {
+		t.Errorf("got %v docs when filtering by list.a, want 1", got)
+	}
+	got = count(coll.Query().Where("map.b", "=", "B").Get(ctx))
+	if got != 1 {
+		t.Errorf("got %v docs when filtering by map.b, want 1", got)
+	}
+}
+
 func TestSortDocs(t *testing.T) {
 	newDocs := func() []storedDoc {
 		return []storedDoc{

docstore/memdocstore/query.go

@@ -37,7 +37,7 @@ func (c *collection) RunGetQuery(_ context.Context, q *driver.Query) (driver.Doc
 
 	var resultDocs []storedDoc
 	for _, doc := range c.docs {
-		if filtersMatch(q.Filters, doc) {
+		if filtersMatch(q.Filters, doc, c.opts.AllowNestedSlicesQuery) {
 			resultDocs = append(resultDocs, doc)
 		}
 	}
@@ -74,17 +74,17 @@ func (c *collection) RunGetQuery(_ context.Context, q *driver.Query) (driver.Doc
 	}, nil
 }
 
-func filtersMatch(fs []driver.Filter, doc storedDoc) bool {
+func filtersMatch(fs []driver.Filter, doc storedDoc, nested bool) bool {
 	for _, f := range fs {
-		if !filterMatches(f, doc) {
+		if !filterMatches(f, doc, nested) {
 			return false
 		}
 	}
 	return true
 }
 
-func filterMatches(f driver.Filter, doc storedDoc) bool {
-	docval, err := getAtFieldPath(doc, f.FieldPath)
+func filterMatches(f driver.Filter, doc storedDoc, nested bool) bool {
+	docval, err := getAtFieldPath(doc, f.FieldPath, nested)
 	// missing or bad field path => no match
 	if err != nil {
 		return false
@@ -138,6 +138,19 @@ func compare(x1, x2 interface{}) (int, bool) {
 		}
 		return -1, true
 	}
+	if v1.Kind() == reflect.Slice {
+		for i := 0; i < v1.Len(); i++ {
+			if c, ok := compare(x2, v1.Index(i).Interface()); ok {
+				if !ok {
+					return 0, false
+				}
+				if c == 0 {
+					return 0, true
+				}
+			}
+		}
+		return -1, true
+	}
 	if v1.Kind() == reflect.String && v2.Kind() == reflect.String {
 		return strings.Compare(v1.String(), v2.String()), true
 	}