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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"
"errors"
"fmt"
"net/url"
"os"
"strings"
"sync"
"go.mongodb.org/mongo-driver/mongo"
"gocloud.dev/docstore"
)
func init() {
docstore.DefaultURLMux().RegisterCollection(Scheme, new(defaultDialer))
}
// defaultDialer dials a default Mongo server based on the environment variable
// MONGO_SERVER_URL.
type defaultDialer struct {
init sync.Once
opener *URLOpener
err error
}
func (o *defaultDialer) OpenCollectionURL(ctx context.Context, u *url.URL) (*docstore.Collection, error) {
o.init.Do(func() {
serverURL := os.Getenv("MONGO_SERVER_URL")
if serverURL == "" {
o.err = errors.New("MONGO_SERVER_URL environment variable is not set")
return
}
client, err := Dial(ctx, serverURL)
if err != nil {
o.err = fmt.Errorf("failed to dial default Mongo server at %q: %v", serverURL, err)
return
}
o.opener = &URLOpener{Client: client}
})
if o.err != nil {
return nil, fmt.Errorf("open collection %s: %v", u, o.err)
}
return o.opener.OpenCollectionURL(ctx, u)
}
// Scheme is the URL scheme mongodocstore registers its URLOpener under on
// docstore.DefaultMux.
const Scheme = "mongo"
// URLOpener opens URLs like "mongo://mydb/mycollection".
// See https://docs.mongodb.com/manual/reference/limits/#naming-restrictions for
// naming restrictions.
//
// The URL Host is used as the database name.
// The URL Path is used as the collection name.
//
// The following query parameters are supported:
//
// - id_field (optional): the field name to use for the "_id" field.
type URLOpener struct {
// A Client is a MongoDB client that performs operations on the db, must be
// non-nil.
Client *mongo.Client
// Options specifies the options to pass to OpenCollection.
Options Options
}
// OpenCollectionURL opens the Collection URL.
func (o *URLOpener) OpenCollectionURL(ctx context.Context, u *url.URL) (*docstore.Collection, error) {
q := u.Query()
idField := q.Get("id_field")
q.Del("id_field")
o.Options.RevisionField = q.Get("revision_field")
q.Del("revision_field")
for param := range q {
return nil, fmt.Errorf("open collection %s: invalid query parameter %q", u, param)
}
dbName := u.Host
if dbName == "" {
return nil, fmt.Errorf("open collection %s: URL must have a non-empty Host (database name)", u)
}
collName := strings.TrimPrefix(u.Path, "/")
if collName == "" {
return nil, fmt.Errorf("open collection %s: URL must have a non-empty Path (collection name)", u)
}
return OpenCollection(o.Client.Database(dbName).Collection(collName), idField, &o.Options)
}
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