I have permalinks with numbers on the end like example_3 and I want to decrement each in a mongoDb update ( i.e. example_2) but it's text. Is there a way to do this?
posts.update(
{ 'title':doc.title, 'student':username, 'copy':false, 'class_number':{ '$gt': doc.class_number } },
{ '$inc': { 'class_number':-1, 'permalink':-1 } },
{ multi: true },
function(err, dox){
if (err) return callback(err, null);
console.log('decclassnumber');
console.log(dox + ' posts were decremented.');
callback(err, dox);
});
It doesn't make sense to increment/decrement an alphanumeric string; you need to separate the original string value into meaningful parts before asking MongoDB (or your application code) to adjust the numeric portion.
Normally with permalinks you would also be incrementing values rather than decrementing -- the whole intent of permalinks is to ensure that a given link is always pointing to the same resource.
It sounds like you actually want to implement a sequence pattern, where you find the next available sequence value to use.
For example, see: Create an Auto-Incrementing Sequence in the MongoDB manual.
Here's a slightly modified version of the getNextSequence() function in the documentation that uses upsert to either find an existing slug counter document or insert a new one. The return value is a new unique slug:
function getNextSequence(name) {
var ret = db.counters.findAndModify(
{
query: { _id: name },
update: { $inc: { seq: 1 } },
upsert: true,
new: true,
}
);
// Return the new slug (eg: "example_1")
return name + '_' + ret.seq;
}
> getNextSequence("example")
example_1
> getNextSequence("example")
example_2
> getNextSequence("example")
example_3
If you do want to decrement from some starting value, you could insert a starting value for your sequence and reduce that instead with $inc: { seq: -1 }.
Related
Is there any built in function in mongodb which accepts an array as input, add each as item as a document, if the document already exist, based on unique indexes (see below), then the document is replaced
In my schema I got these indexes which defines the what calculation is unique
calculationSchema.index(
{ insId: 1, year: 1, month: 1, day: 1 },
{ unique: true }
);
Create function
export const createCalculations = async (calculations: ICalculation[]) => {
try {
const createdCalculations = await mongoose
.model("calculation")
.create(calculations); // Replace if it exist based on indexs above, otherwise create it
return Promise.resolve(createdCalculations);
} catch (err) {
console.log(err);
return Promise.reject(err);
}
};
This query works perfectly
{
$or:[{author:this.userId} , {somethingelse:true} ]
}
But when I try:
{
$or:[{author:this.userId} , {sharedwith[this.userId]:true} ]
}
I receive the message
Errors prevented startup:
While processing files with ecmascript (for target os.linux.x86_64): server/main.js:113:43: Unexpected token, expected
, (113:43)
=> Your application has errors. Waiting for file change.
And thats where the comma , in the $or statement is
Help
I guess that you are trying to retrieve all documents for which the current user is the author, or which have been shared with him/her? And therefore that you have structured your documents with a sharedWith field which is a hash map of userId as keys and boolean as value?
Document structure:
{
author: string,
sharedWith: {
<userId1>: boolean
// <userId2>…
}
}
In that case, your MongoDB query should use the dot notation to specify the value of a nested field within sharedWith field:
{
$or: [{
author: string
}, {
"sharedWith.<userId>": boolean
}]
}
To easily create the query with the interpolated value of <userId>, you can use a computed key in your object (ES6 syntax):
{
$or:[{
author: this.userId
} , {
// The query computed key must be in square brackets.
// Specify the field child key using the dot notation within your query.
["sharedwith." + this.userId]: true
}]
}
Or with good old ES5 syntax, similarly to #MichelFloyd's answer:
var query = {
$or: [{
author: this.userId
}]
};
var newCondition = {};
newCondition["sharedWith." + this.userId] = true;
query.$or.push(newCondition);
Note: the above described document structure could conveniently replace the sharedWith hash map by an array (since having a false value for the boolean could simply be replaced by removing the corresponding userId from the array):
{
author: string,
sharedWith: [
<userId1>
// <userId2>…
]
}
In which case the query would simply become:
{
$or:[{
author: this.userId
} , {
// In MongoDB query, the below selector matches either:
// - documents where `sharedWith` value is a string equal to
// the value of `this.userId`, or
// - documents where `sharedWith` value is an array which contains
// an element with the same value as `this.userId`.
sharedwith: this.userId
}]
}
Try building the query as a variable before running it.
let query = { $or: [{ author: this.userId }]};
const sw = sharedwith[this.userId];
query.$or.push({sw: true});
MyCollection.find(query);
I have a very certain thing i want to accomplish, and I wanted to make sure it is not possible in mongoose/mongoDB before I go and code the whole thing myself.
I checked mongoose-ttl for nodejs and several forums and didn't find quite what I need.
here it is:
I have a schema with a date field createDate. Now i wish to place a TTL on that field, so far so good, i can do it like so (expiration in 5000 seconds):
createDate: {type: Date, default: Date.now, expires: 5000}
but I would like my users to be able to "up vote" documents they like so those documents will get a longer period of time to live, without changing the other documents in my collection.
So, Can i change a TTL of a SINGLE document somehow once a user tells me he likes that document using mongoose or other existing npm related modules?
thank you
It has been more than a year, but this may be useful for others, so here is my answer:
I was trying accomplish this same thing, in order to allow a grace period after an entry deletion, so the user can cancel the operation afterwards.
As stated by Mike Bennett, you can use a TTL index making documents expire at a specific clock time.
Yo have to create an index, setting the expireAfterSeconds to zero:
db.yourCollection.createIndex({ "expireAt": 1 }, { expireAfterSeconds: 0 });
This will not affect any of the documents in your collection, unless you set expireAfterSeconds on a particular document like so:
db.log_events.insert( {
"expireAt": new Date('July 22, 2013 14:00:00'),
"logEvent": 2,
"logMessage": "Success!"
} )
Example in mongoose
Model
var BeerSchema = new Schema({
name: {
type: String,
unique: true,
required: true
},
description: String,
alcohol: Number,
price: Number,
createdAt: { type: Date, default: Date.now }
expireAt: { type: Date, default: undefined } // you don't need to set this default, but I like it there for semantic clearness
});
BeerSchema.index({ "expireAt": 1 }, { expireAfterSeconds: 0 });
Deletion with grace period
Uses moment for date manipulation
exports.deleteBeer = function(id) {
var deferred = q.defer();
Beer.update(id, { expireAt: moment().add(10, 'seconds') }, function(err, data) {
if(err) {
deferred.reject(err);
} else {
deferred.resolve(data);
}
});
return deferred.promise;
};
Revert deletion
Uses moment for date manipulation
exports.undeleteBeer = function(id) {
var deferred = q.defer();
// Set expireAt to undefined
Beer.update(id, { $unset: { expireAt: 1 }}, function(err, data) {
if(err) {
deferred.reject(err);
} else {
deferred.resolve(data);
}
});
return deferred.promise;
};
You could use the expire at clock time feature in mongodb. You will have to update the expire time each time you want to extend the expiration of a document.
http://docs.mongodb.org/manual/tutorial/expire-data/#expire-documents-at-a-certain-clock-time
I'm trying to update a sub document on an existing collection. I'm getting a MongoDB error message.
"MongoError: The positional operator did not find the match needed from the query. Unexpanded update: articleWords.$ [409]"
From my Articles Simple Schema
"articleWords.$": {
type: Object
},
"articleWords.$.wordId": {
type: String,
label: 'Word ID'
},
"articleWords.$.word": {
type: String,
label: 'Word'
},
Update Function
function updateArticle(_id,wordArr) {
_.each(wordArr,function(elem) {
var ret = Articles.update(
{'_id': _id},
{ $set: { 'articleWords.$': { 'wordId': elem.wordId, 'word': elem.word } }
});
});
return true;
}
As you can see I am passing an array of objects. Is there a better way to do this than _.each ?
CLARIFICATION
Thank you to #corvid for the answer. I think I didn't make my question clear enough. There does exist an article record, but there is no data added to the articleWords attribute. Essentially we are updating a record but insert into the articleWords array.
A second attempt, is also not working
_.each(wordArr,function(elem) {
var ret = Articles.update(
{'_id': _id},
{ $set: { 'articleWords.$.wordId': elem.wordId, 'articleWords.$.word': elem.word } }
);
});
Yes, you need your selector to match something within the subdocument. For example,
Articles.update({
'_id': <someid>,
'words.wordId': <somewordid>
}, {
$set: {
'words.$.word': elem.word,
'words.$.wordId': elem.wordId
}
});
If the array doesn't exist yet then you're going about this in the hardest way possible. You can just set the entire array at one go:
var ret = Articles.update(
{'_id': _id},
{ $set: { articleWords: wordArr }}
);
I can see that wordArr already has the id and string. This will work as long as it doesn't have more content. If it does then you can just make a second version with the parts you want to keep.
My app has several users, each user has documents. Each documents needs to have a sequence number, that may look something like this: 2013-1, 2013-2 (year and sequence number), or perhaps just a simple number: 1, 2, 3...
Currently, I am assigning the sequence number from user's settings when the Mongoose docuemnt is created. Based on that sequence number and the number format from user's settings, I am generating the final document number.
What I realized is that when 2 documents are created at the same time, they will get exactly the same number, because I am incrementing the sequence number in settings just after I have saved a document. But I am assigning the sequence number when I am creating (not saving yet) the document so the sequence number will be exactly the same for both documents.
I obviously need a way to handle this sequence number auto-incrementing at the moment of saving...
How can I assure that this number is unique and automatically incremented/generated?
#emre and #WiredPraire pointed me to the right direction, but I wanted to provide a full Mongoose-compatible answer to my question. I ended up with the following solution:
var Settings = new Schema({
nextSeqNumber: { type: Number, default: 1 }
});
var Document = new Schema({
_userId: { type: Schema.Types.ObjectId, ref: "User" },
number: { type: String }
});
// Create a compound unique index over _userId and document number
Document.index({ "_userId": 1, "number": 1 }, { unique: true });
// I make sure this is the last pre-save middleware (just in case)
Document.pre('save', function(next) {
var doc = this;
// You have to know the settings_id, for me, I store it in memory: app.current.settings.id
Settings.findByIdAndUpdate( settings_id, { $inc: { nextSeqNumber: 1 } }, function (err, settings) {
if (err) next(err);
doc.number = settings.nextSeqNumber - 1; // substract 1 because I need the 'current' sequence number, not the next
next();
});
});
Please note that with this method there is no way to require the number path in the schema, and there is no point as well, because it is automatically added.
You can achieve that through:
create sequence generator, which is just another document that keeps a counter of the last number.
Use a mongoose middleware to update the auto increment the desired field.
Here is a working and tested example with the todo app.
var mongoose = require('mongoose');
mongoose.connect('mongodb://localhost/todoApp');
// Create a sequence
function sequenceGenerator(name){
var SequenceSchema, Sequence;
SequenceSchema = new mongoose.Schema({
nextSeqNumber: { type: Number, default: 1 }
});
Sequence = mongoose.model(name + 'Seq', SequenceSchema);
return {
next: function(callback){
Sequence.find(function(err, data){
if(err){ throw(err); }
if(data.length < 1){
// create if doesn't exist create and return first
Sequence.create({}, function(err, seq){
if(err) { throw(err); }
callback(seq.nextSeqNumber);
});
} else {
// update sequence and return next
Sequence.findByIdAndUpdate(data[0]._id, { $inc: { nextSeqNumber: 1 } }, function(err, seq){
if(err) { throw(err); }
callback(seq.nextSeqNumber);
});
}
});
}
};
}
// sequence instance
var sequence = sequenceGenerator('todo');
var TodoSchema = new mongoose.Schema({
name: String,
completed: Boolean,
priority: Number,
note: { type: String, default: '' },
updated_at: { type: Date, default: Date.now }
});
TodoSchema.pre('save', function(next){
var doc = this;
// get the next sequence
sequence.next(function(nextSeq){
doc.priority = nextSeq;
next();
});
});
var Todo = mongoose.model('Todo', TodoSchema);
You can test it out in the node console as follows
function cb(err, data){ console.log(err, data); }
Todo.create({name: 'hola'}, cb);
Todo.find(cb);
With every newly created object the you will see the priority increasing. Cheers!
This code is taken from MongoDB manual and it actually describes making the _id field auto increment. However, it can be applied to any field. What you want is to check whether the inserted value exists in database just after you inserted your document. If it is allready inserted, re increment the value then try to insert again. This way you can detect dublicate values and re-increment them.
while (1) {
var cursor = targetCollection.find( {}, { f: 1 } ).sort( { f: -1 } ).limit(1);
var seq = cursor.hasNext() ? cursor.next().f + 1 : 1;
doc.f = seq;
targetCollection.insert(doc);
var err = db.getLastErrorObj();
if( err && err.code ) {
if( err.code == 11000 /* dup key */ )
continue;
else
print( "unexpected error inserting data: " + tojson( err ) );
}
break;
}
In this example f is the field in your document that you want to auto increment. To make this work you need to make your field UNIQUE which can be done with indexes.
db.myCollection.ensureIndex( { "f": 1 }, { unique: true } )
You can use mongoose-auto-increment package as follows:
var mongoose = require('mongoose');
var autoIncrement = require('mongoose-auto-increment');
/* connect to your database here */
/* define your DocumentSchema here */
autoIncrement.initialize(mongoose.connection);
DocumentSchema.plugin(autoIncrement.plugin, 'Document');
var Document = mongoose.model('Document', DocumentSchema);
You only need to initialize the autoIncrement once.