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135 lines
4.1 KiB
135 lines
4.1 KiB
// Copyright (C) MongoDB, Inc. 2017-present.
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//
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// Licensed under the Apache License, Version 2.0 (the "License"); you may
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// not use this file except in compliance with the License. You may obtain
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// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
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package driver
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import (
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"context"
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"errors"
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"io"
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"strings"
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"go.mongodb.org/mongo-driver/x/bsonx/bsoncore"
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)
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// ListCollectionsBatchCursor is a special batch cursor returned from ListCollections that properly
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// handles current and legacy ListCollections operations.
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type ListCollectionsBatchCursor struct {
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legacy bool // server version < 3.0
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bc *BatchCursor
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currentBatch *bsoncore.DocumentSequence
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err error
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}
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// NewListCollectionsBatchCursor creates a new non-legacy ListCollectionsCursor.
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func NewListCollectionsBatchCursor(bc *BatchCursor) (*ListCollectionsBatchCursor, error) {
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if bc == nil {
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return nil, errors.New("batch cursor must not be nil")
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}
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return &ListCollectionsBatchCursor{bc: bc, currentBatch: new(bsoncore.DocumentSequence)}, nil
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}
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// NewLegacyListCollectionsBatchCursor creates a new legacy ListCollectionsCursor.
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func NewLegacyListCollectionsBatchCursor(bc *BatchCursor) (*ListCollectionsBatchCursor, error) {
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if bc == nil {
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return nil, errors.New("batch cursor must not be nil")
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}
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return &ListCollectionsBatchCursor{legacy: true, bc: bc, currentBatch: new(bsoncore.DocumentSequence)}, nil
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}
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// ID returns the cursor ID for this batch cursor.
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func (lcbc *ListCollectionsBatchCursor) ID() int64 {
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return lcbc.bc.ID()
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}
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// Next indicates if there is another batch available. Returning false does not necessarily indicate
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// that the cursor is closed. This method will return false when an empty batch is returned.
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//
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// If Next returns true, there is a valid batch of documents available. If Next returns false, there
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// is not a valid batch of documents available.
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func (lcbc *ListCollectionsBatchCursor) Next(ctx context.Context) bool {
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if !lcbc.bc.Next(ctx) {
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return false
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}
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if !lcbc.legacy {
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lcbc.currentBatch.Style = lcbc.bc.currentBatch.Style
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lcbc.currentBatch.Data = lcbc.bc.currentBatch.Data
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lcbc.currentBatch.ResetIterator()
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return true
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}
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lcbc.currentBatch.Style = bsoncore.SequenceStyle
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lcbc.currentBatch.Data = lcbc.currentBatch.Data[:0]
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var doc bsoncore.Document
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for {
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doc, lcbc.err = lcbc.bc.currentBatch.Next()
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if lcbc.err != nil {
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if lcbc.err == io.EOF {
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lcbc.err = nil
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break
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}
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return false
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}
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doc, lcbc.err = lcbc.projectNameElement(doc)
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if lcbc.err != nil {
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return false
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}
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lcbc.currentBatch.Data = append(lcbc.currentBatch.Data, doc...)
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}
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return true
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}
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// Batch will return a DocumentSequence for the current batch of documents. The returned
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// DocumentSequence is only valid until the next call to Next or Close.
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func (lcbc *ListCollectionsBatchCursor) Batch() *bsoncore.DocumentSequence { return lcbc.currentBatch }
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// Server returns a pointer to the cursor's server.
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func (lcbc *ListCollectionsBatchCursor) Server() Server { return lcbc.bc.server }
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// Err returns the latest error encountered.
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func (lcbc *ListCollectionsBatchCursor) Err() error {
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if lcbc.err != nil {
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return lcbc.err
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}
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return lcbc.bc.Err()
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}
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// Close closes this batch cursor.
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func (lcbc *ListCollectionsBatchCursor) Close(ctx context.Context) error { return lcbc.bc.Close(ctx) }
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// project out the database name for a legacy server
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func (*ListCollectionsBatchCursor) projectNameElement(rawDoc bsoncore.Document) (bsoncore.Document, error) {
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elems, err := rawDoc.Elements()
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if err != nil {
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return nil, err
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}
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var filteredElems []byte
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for _, elem := range elems {
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key := elem.Key()
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if key != "name" {
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filteredElems = append(filteredElems, elem...)
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continue
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}
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name := elem.Value().StringValue()
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collName := name[strings.Index(name, ".")+1:]
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filteredElems = bsoncore.AppendStringElement(filteredElems, "name", collName)
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}
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var filteredDoc []byte
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filteredDoc = bsoncore.BuildDocument(filteredDoc, filteredElems)
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return filteredDoc, nil
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}
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// SetBatchSize sets the batchSize for future getMores.
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func (lcbc *ListCollectionsBatchCursor) SetBatchSize(size int32) {
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lcbc.bc.SetBatchSize(size)
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}
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