I already have an established database connection. I need to list the names of the collections in the database. Is it possible?
db.collectionNames(function(err, collectionArrayResult) {
//Now do something with collectionArrayResult
});
The result is an array of objects with a 'name' property, like this:
[
{ name: '<dbName>.<collectionName>' },
...
]
Careful though - <dbName>.system.indexes will be returned too.
To show collections into database from mongo shell :
db.getCollectionNames()
So to show collection in mongoskin try that
var collections = db.collections();
collections.each(function(err, collection) {
console.log(collection);
});
according to this link Mongoskin Tutorial
Related
I want to get all distinct keys from a collections in mongoDB.
I refereed the following links:
Get names of all keys in the collection
Querying for a list of all distinct fields in MongoDB collection and etc.
But still i didn't get the right solution...
As i am using mongoose in the first link reference syas runCommand is not a function.
As findOne() will give the first document keys alone but i need all distnct keys
userModel.findOne(condition, projection, callback)
Please share your ideas..
If you are using Mongoose 3.x, then you can try this :
userModel.find().distinct('_id', function(error, ids) {
// ids is an array of all ObjectIds
});
Or you can find all the documents and extract key from that like :
var keys = {};
var docKeys = [];
userModel.find({}, function(err, allDocs){
allDocs.forEach(function(doc){
docKeys = Object.keys(doc);
docKeys.forEach(function(docKey){
if(!keys[docKey]) keys[docKey] = true;
})
})
})
I have just written for getting logic, you can change according to your requirements and efficiency
Try like this you will get all of your keys defined into your mongoose model/Schema.
import Model from 'your_model_path'
for(let property in Model.schema.obj){
console.log("key=====>",property);
}
I'm trying a very simple CRUD API with the MEAN stack. I entered several documents into a mongolab sandbox db. I could do a GET on all documents and they would all be returned. Then I tested GET by ID:
router.route('/api/v1/resources/:resource_id')
// get the resource with that id (accessed at GET http://localhost:8080/api/resources/:resource_id)
.get(function(req, res) {
Resource.findById(req.params.resource_id, function(err, resources) {
if (err)
res.send(err);
res.json(resources);
});
});
And it simply wouldn't work. I kept getting null. But the document existed. I could see it when I would do a GET on all documents.
Then I got another document to return, finally.
The difference? The record that returned had an id in this format:
{
"_id": { "$oid":"1234567890abc"}
}
But records that did not return had this:
{
"_id": "1234567890abc"
}
Can Anyone explain this to me? I entered the data with Postman and I didn't do anything different between the entries.
What is $oid?
What creates the $oid?
Why does that nesting matter for mongoose's findById()?
Thanks!
$oid is from Strict MongoDB Extended JSON.
All your queries to MongoDB database that contains _id conditions should wrap _id in ObjectId function like the following:
db.resources.findOne({_id: ObjectId("507c35dd8fada716c89d0013")};
MongoLab provides UI for querying to MongoDB via JSON syntax. But you can't use ObjectId in JSON due specification restrictions.
So, MongoLab uses Strict MongoDB Extended JSON for alias ObjectId() -> $oid.
{"_id": {"$oid":"507c35dd8fada716c89d0013"})
Same $oid you see in the output because MongoLab UI uses JSON also.
Mongoose automatically converts a string _id to MongoDB query so you don't need doing it manually. The following queries are equivalent:
Resource.findById("507c35dd8fada716c89d0013");
Resource.findById(new mongoose.Types.ObjectId("507c35dd8fada716c89d0013"));
I have 2 collections in my mongodb database: users and posts.
And in posts collection I have DBRef field like this:
user : DBRef('users', ObjectId('...'), null)
When I'm going to remove some post by user id, I do the following:
db.posts.remove({ 'user.$id' : ObjectId('...') })
And it works great, but not from node-mongodb-native. From node-mongodb-native I'm getting following error while doing this request:
key must not contain '.'
Can anyoune see that? Thank you for your help and explanations if I'm wrong in something.
Update
find requests by DBRef $id work fine!
Node.js code:
var mongodb = require('mongodb')
, nconf = require('nconf')
, MongoClient = mongodb.MongoClient;
MongoClient.connect(nconf.get('db:connectionString'), function(mongoConnectionError, db) {
if (mongoConnectionError) throw mongoConnectionError;
db
.collection('posts')
.remove({ 'user.$id' : new mongodb.ObjectID('...') }, {}, function(err, removedItems) {
if (err) { throw err; }
console.log('Removed items: ' + removedItems);
});
});
I've used a similar model, but my post was from ONE user, making it simply:
db.posts.remove({'user_id' : ObjectID('...') });
In this case, it looks more like the collection posts has an array user with id in it.
If I'm not mistaken, you should use the $ in the user array to do something to an element in an array once you've matched.
If your purpose is removing the entire post, simply remove it by matching the id in the users array:
db.posts.remove({user:{$in:ObjectID('...'}});
Otherwise, $pull, as said above.
So I have a model that is for a recipe where it has a relation of 'ingredients' and that is just an array of ObjectIds. When I run the following query on mongo shell it works fine and returns all my data.
Example model :
{
"name": "...",
"_id": ObjectId("530ca903746515c0161e6b9f"),
"ingredients": [
ObjectId("53069363ff7447a81a3a7a1d"),
ObjectId("53069363ff7447a81a3a7a17")
]
}
Query:
db.drink.find({"ingredients":{"$in":[ObjectId("53069364ff7447a81a3a7a87"), ObjectId("530fb948c1a3ff480d58e43c")]}});
Using sails.js though their waterline orm, they don't really have a way to query this though or at least through any possible google search that I can find. So trying to use the native driver I have something like the following -
var ings = new Array();
for (var i in req.body) {
ings.push(new ObjectID(req.body[i].toString()));
}
Drink.native(function(err, collection){
if(err){
return res.send(err, 500);
} else {
collection.find({"ingredients":{"$in":ings}}).toArray(function(err, data){
console.log(data);
});
}
});
The thing is the data array returned in the callback is always empty. If I check the 'ings' array it is an array of objectids so I am not sure why it won't return any data. If I remove the json object in the 'find' function it does return everything. Anyone have any idea how to make this query return data when using sails.js?
The code above actually is working it was an internal data issue on the mongodb where IDs were not matching between relations. When the relations were rebuilt all is working as it should be.
I am having a rather interesting problem using mongoDB's $addToSet to an array full of ObjectIds.
In my mongoose schema ("Happening"), I declare an array of ObjecIds called "expected", to be used by .populate().
expected: [{type: Schema.Types.ObjectId, ref: "User" }]
... which works nicely everywhere I use it. So far so good.
I then attempt to update the Happening.expected array using $addToSet as outlined here:
http://docs.mongodb.org/manual/reference/operator/addToSet/
like so:
app.get("/happening/yamobethere/:id", ensureLoggedIn("/login"),
function (req, res) {
// userId is the mongo ObjectId of the user record
var userId = req.session.user.id,
eventId = req.params.id;
models.Happening.update(
{_id: eventId}, {
$addToSet: {expected: userId}
},
function(err, updated){
if (err) {
res.json({"error": err});
}
res.json({"updated": updated});
});
});
... which always yields:
{updated: 1}
Now the docs lead me to expect the actual userId that I passed in, so the "1" is a bit odd. I expected it to be a fail, and in light of the weirdness that happens next, it appears to be a mongodb error of some sort percolating it's way back to me as results.
The weirdness is, when I check my database, I see that indeed a new ObjectId has been added: just not the one I passed in.
"expected" : [
ObjectId("51cb18623ade2b9f1e000004"),
ObjectId("51cdb7c12f0e58bdb3000001")
],
becomes
"expected" : [
ObjectId("51cb18623ade2b9f1e000004"),
ObjectId("51cdb7c12f0e58bdb3000001"),
ObjectId("51cdb80e09612bfab3000002")
],
The new ObjectId does not appear in any of my collections. It appears to be an orphan, but I'm a mongo noob, so I may be full of compost on this.
I did attempt to cast the userId as an ObjectId:
$addToSet: {expected: mongoose.Types.ObjectId.fromString(userId)}
but that changed nothing, and really should not be necessary, since the schema should handle it.
I'd really rather not resort to downloading the entire object, appending the value to the "expected" array, then sending the whole schmear back for an update.
Any help appreciated, folks. Thanks!
Update:
A colleague suggested the following technique:
var addMe = {$addToSet: {expected: userId}};
models.Happening.findByIdAndUpdate(eventId, addMe, function(err, me) {
if (err) {
return json(err);
}
res.json(200, me);
});
... which is a bit of an improvement, since it actually returns an object for me to inspect. Unfortunately, it also results in orphaned ObjecIds appearing in the array, rather than the existing userId value I specified.
Thanks again!
It appears that my passport strategy is returning the ObjectID of the rejected attempted creation of a new user in the db via data from oauth. So, the code is fine, my data is garbage.
Never trust anything, and be prepared to look like a boob. :-)
Thanks for the clarification on my return values JohnnyHK.