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Type:
Bug
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Status: Closed
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Priority:
Major - P3
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Resolution: Fixed
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Affects Version/s: 3.5.4
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Fix Version/s: 3.5.5
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Component/s: None
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Labels:None
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MongoDB Version:Not Applicable
From user Peter Broadhurst:
We've had to pin our version to 3.5.3 as this code change changed behaviour.
Simple sample recreate of the change in behavior:
async function run() {
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const MongoClient = require('mongodb').MongoClient;
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const client = await MongoClient.connect(process.env.MONGODB_URL);
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const db = client.db('354regr');
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const collection = db.collection('numbers');
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try {
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await collection.deleteMany({});
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for (let i = 0; i < 10; i++) await collection.insertOne({i});
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let cursor = await collection.find({});
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cursor.limit(5);
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while (await cursor.hasNext()) {
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const doc = await cursor.next();
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console.log(`Doc: ${JSON.stringify(doc)}`);
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}
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}
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catch(err) {
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console.error(err.stack);
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}
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client.close();
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}
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run()
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Output with mongodb@3.5.3 (or mongodb@3.5.2 and previous) - see the limit of 5 records returned as expected:
Doc: {"_id":"5e6012c0bab232836f58f35b","i":0}
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Doc: {"_id":"5e6012c0bab232836f58f35c","i":1}
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Doc: {"_id":"5e6012c0bab232836f58f35d","i":2}
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Doc: {"_id":"5e6012c0bab232836f58f35e","i":3}
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Doc: {"_id":"5e6012c0bab232836f58f35f","i":4}
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Output with mongodb@3.5.4:
Doc: {"_id":"5e601344f32806839a905a99","i":0}
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Doc: {"_id":"5e601344f32806839a905a9a","i":1}
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Doc: null
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MongoError: Cursor is closed
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at Function.create (/private/tmp/node_modules/mongodb/lib/core/error.js:43:12)
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at Cursor.hasNext (/private/tmp/node_modules/mongodb/lib/cursor.js:197:24)
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at run (/private/tmp/t/index.js:12:25)
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at process._tickCallback (internal/process/next_tick.js:68:7)
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See that each time hasNext is called, it seems to be consuming one of the limit entries, resulting in a null doc being returned on the third call to next() and the cursor being closed.
- is duplicated by
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- Closed
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