/
query.go
105 lines (95 loc) · 2.81 KB
/
query.go
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// Copyright 2019 The Go Cloud Development Kit Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package mongodocstore
import (
"context"
"fmt"
"io"
"strings"
"go.mongodb.org/mongo-driver/bson"
"go.mongodb.org/mongo-driver/mongo"
"go.mongodb.org/mongo-driver/mongo/options"
"gocloud.dev/internal/docstore/driver"
)
func (c *collection) RunGetQuery(ctx context.Context, q *driver.Query) (driver.DocumentIterator, error) {
opts := options.Find()
if len(q.FieldPaths) > 0 {
opts.Projection = projectionDoc(q.FieldPaths)
}
if q.Limit > 0 {
lim := int64(q.Limit)
opts.Limit = &lim
}
filter := bson.D{} // must be a zero-length slice, not nil
for _, f := range q.Filters {
bf, err := filterToBSON(f)
if err != nil {
return nil, err
}
filter = append(filter, bf)
}
cursor, err := c.coll.Find(ctx, filter, opts)
if err != nil {
return nil, fmt.Errorf("Find: %v", err)
}
return &docIterator{cursor: cursor, ctx: ctx}, nil
}
var mongoQueryOps = map[string]string{
driver.EqualOp: "$eq",
">": "$gt",
">=": "$gte",
"<": "$lt",
"<=": "$lte",
}
// filterToBSON converts a driver.Filter to the MongoDB equivalent, expressed
// as a bson.E (key-value pair).
// The MongoDB document corresponding to "field op value" is
// {field: {mop: value}}
// where mop is the mongo version of op (see the mongoQueryOps map above).
func filterToBSON(f driver.Filter) (bson.E, error) {
key := strings.Join(f.FieldPath, ".")
val, err := encodeValue(f.Value)
if err != nil {
return bson.E{}, err
}
op := mongoQueryOps[f.Op]
if op == "" {
return bson.E{}, fmt.Errorf("no mongo operator for %q", f.Op)
}
return bson.E{Key: key, Value: bson.D{{Key: op, Value: val}}}, nil
}
type docIterator struct {
cursor *mongo.Cursor
ctx context.Context // remember for Stop
}
func (it *docIterator) Next(ctx context.Context, doc driver.Document) error {
if !it.cursor.Next(ctx) {
if it.cursor.Err() != nil {
return it.cursor.Err()
}
return io.EOF
}
var m map[string]interface{}
if err := it.cursor.Decode(&m); err != nil {
return fmt.Errorf("cursor.Decode: %v", err)
}
return decodeDoc(m, doc)
}
func (it *docIterator) Stop() {
// Ignore error on Close.
_ = it.cursor.Close(it.ctx)
}
func (c *collection) QueryPlan(q *driver.Query) (string, error) {
return "unknown", nil
}