Given a schema that looks like this:
var schema = new mongoose.Schema({ name: 'string', size: 'string' });
And the database contains "name" for all objects in the collection. But then I change it and remove name
var schema = new mongoose.Schema({ size: 'string' });
And then I do a find on it:
schema.find({}).exec().then( (objs) => {
// objs[0].name still exists
I thought that if the schema didn't specify a property then it wouldn't exist on the found objects. Is this not the case? Is the only way to remove a property, to actually remove it from the object in mongo?
Quoting from the original maintainer, Aaron Heckmann:
[M]ongoose "plays nice" with existing data in the db, not deleting it unless you tell it to.
[D]eleting the property would work if mongoose was able to hook into that even but alas it cannot. [H]owever you can completely remove the property from your document by setting the values to undefined which will trigger an $unset.
Source: Google Groups
Basically Mongoose attempts to be non-destructive to existing data. If a property is no longer needed you could run an update on the database to unset the value which would remove the property from every document in the collection.
Related
I want to be able to add a new object property to an object in a document stored in a mongodb database where the model schema does not include that property. I've seen all sorts of examples on google and none of them seem to work so I want to ask this question myself and get some direct answers.
For example take this scheme
const MapSchema = new mongoose.Schema({
name:{
type: String
}
})
const ListMap = mongoose.model("listmap", MapSchema);
Now I want to add a new property to it using its id
model.ListMap.findByIdAndUpdate(_id, {newprop:"whatever");
model.ListMap.findByIdAndUpdate(_id, {name:"test");
Using those two commands, I can add name:"test" to it but I can not add newprop:"whatever" to it. What I want to do is be able to add a new property without having to declare it in the schema first. I know this seems like it has been asked before but I've googled it all and I don't believe anyone has answered it. They either didn't understand the question or their code doesn't actually work.
Also bonus question, why does mongodb always add an s to collection names? like the above would show up in collection "listmaps", assuming I used .create() to add the first object.
For your first question, you can not add a property to your schema without declaring it first.
you can define a generic property like this:
const MapSchema = new mongoose.Schema({
property:{
title: String,
value: String
}
})
const ListMap = mongoose.model("listmap", MapSchema);
and for your second question you can refer to this answer:
Why does mongoose always add an s to the end of my collection name
-------SOLVED-------------
I am adding this here for others because it was extremely difficult for me to google this. This answer is from another stackexchange link
How to add a new key:value pair to existing sub object of a mongoDB document
based on this, this is how to do what I proposed earlier
const commentMapSchema = new mongoose.Schema({
List:{}
})
const CommentsMap = mongoose.model("commentmap", commentMapSchema);
const update = {$set: {["List."+"test2"] : "data2"}};
CommentsMap.findByIdAndUpdate(id, update);
First you need to declare the property in the schema. This property can hold more properties exactly like how it works with javascript objects. Then use the update method with mongoose with the query that combines the property name with a new property via dot notation. However when adding a property this way, the key must be a string. This works exactly like it does in javascript. You can just create a new name and it'll add to the object properties.
I hope this helps anyone else who landed here.
I have some Mongoose schemas, whose certain fields need getter and setters.
For that, i've set the following:
MySchema.set('toObject',{getters:true});
MySchema.set('toJSON',{getters:true});
Whenever I send/read the result of MySchema.find(), it gives me both _id and id fields, which have same value.
I think thats a virtual field (correct me if i'm wrong here)
How do i stop this? I don't want to process through each and every object and remove the field.
Documented here:
Mongoose assigns each of your schemas an id virtual getter by default which returns the documents _id field cast to a string, or in the case of ObjectIds, its hexString. If you don't want an id getter added to your schema, you may disable it passing this option at schema construction time.
Just set the id field to false while creating the schema:
var schema = new Schema({ name: String }, { id: false });
I have a Mongoose schema that looks like this:
ManifestSchema = new Schema({
entries: [{
order_id: String,
line_item: {}, // <-- resolved at run time
address: {},// <-- resolved at run time
added_at: Number,
stop: Number,
}]
}, {collection: 'manifests', strict: true });
and somewhere in the code I have this:
Q.ninvoke(Manifests.findById(req.params.id), 'exec')
.then(function(manifest)
{
// ... so many things, like resolving the address and the item information
entry.line_item = item;
entry.address = order.delivery.address;
})
The issue that I faced is that without defining address and line_item in the schema, when I resolved them at run time, they wouldn't returned to the user because they weren't in the schema...so I added them...which cause me another unwanted behavior: When I saved the object back, both address and line_item were saved with the manifest object, something that I would like to avoid.
Is there anyway to enable adding fields to the schema at run time, but yet, not saving them on the way back?
I was trying to use 'virtuals' in mongoose, but they really provide what I need because I don't create the model from a schema, but it rather returned from the database.
Call toObject() on your manifest Mongoose instance to create a plain JavaScript copy that you can add extra fields to for the user response without affecting the doc you need to save:
Q.ninvoke(Manifests.findById(req.params.id), 'exec')
.then(function(manifest)
{
var manifestResponse = manifest.toObject();
// ... so many things, like resolving the address and the item information
entry.line_item = item;
entry.address = order.delivery.address;
})
I want to convert _id variable as id.
So i want to add virtual 'id' field to all the schema i am going to create, that will return the value of '_id' whenever i access 'id' field of the model.
from the documentation http://mongoosejs.com/docs/2.7.x/docs/virtuals.html
i found that, first i have to create schema then apply the virtual 'id' field individually.
I want to simply add virtual field to the base mongoose.Schema and then whenever i will create a new schema, that all will have virtual field without any manual effort on each of the individual schema.
EDIT :
i am also using Backbone.Model and i have created an 'id' field for each model. If i get the simply use id in the front end codes, i get the error that id field not exists. BUT when i set idAttribute as '_id' to each model then everything goes OK. That means backbone model want to have _id, and the reason behind mongoose schema have _id not id. So can i interpret that, mongoose does not automatically add virtual id mapped to _id? Correct me if i am wrong.
For backbone, "id" is it's default idAttribute name, so just don't add any code there and everything will work as intended.
For mongoose, the answer boils down to "it's complicated", but the main points are:
By default mongoose will give each schema a virtual called "id" which will be the document's _id as a string
However, by default .toJSON doesn't include virtuals, so when you send a mongoose document to backbone in the browser, it gets just "_id" and not "id"
to quickly get a JSON representation including the virtuals, use myModelInstance.toJSON({virtuals: true}). You'll get both "_id" and "id"
You need to read up on the transform options for toObject and toJSON to get a full picture of what you can do and how, but the gist is (based on examples straight from the docs)
// specify the transform schema option
if (!schema.options.toJSON) schema.options.toJSON = {};
schema.options.toJSON.transform = function (doc, ret, options) {
// remove the _id of every document before returning the result
delete ret._id;
}
schema.options.toJSON.virtuals = true;
I have an object like this
==================records=========={ Id: 5114a3c21203e0d811000088,
userId: 'test',
sUserId: test,
userName: 'test',
url: 'test',
Title: 'test'
}
I need to add a new field Name : 'test' to the above record, I tried giving records.Name = name, it didn't work.
Helps please
Thanks,
Prats
I am assuming you are trying to add a property to a returned Mongoose Document to reuse it somewhere else. Documents returned by Mongoose are not JSON objects directly, you'll need to convert them to an object to add properties to them. The following should work:
//... record is a mongoose Document
var r = record.toObject();
r.Name = 'test';
console.log("Record ",r);
Those finding this problem, OP mentioned in a comment below the original question that the solution for this problem is:
records.set('Name', 'test')
This adds a new attribute called Name having value test.
Just use,
var convertedJSON = JSON.parse(JSON.stringify(mongooseReturnedDocument);
and Then,
convertedJSON.newProperty = 'Hello!'
'Hello!' can be anything, a number, a object or JSON Object Literal.
Cheers! :)
I experienced a similar problem, and hope that my hours of existential frustration help others in the same situation. My inclination was to believe that documents returned via Mongoose are read-only. This is actually not true.
However, you cannot assign a property to your document that is not also in your Schema.
So, unless your schema has the following:
{
Name: {String}
}
you will be constantly frustrated by trying to assign Name to your document.
Now, there are workarounds in the answers above that also worked for me, but they do not get to the root of the problem:
myDocument.toObject();
JSON.parse(JSON.stringify(myDocument);
These will work, but in my opinion they just hide the problem. The real issue is that Mongoose is smarter than we realized and is enforcing your schema, as it should.
You could also use the lean() method, e.g. const users = await Users.find().lean().exec()
From the mongoose documentation:
Documents returned from queries with the lean option enabled are plain
javascript objects, not MongooseDocuments. They have no save method,
getters/setters or other Mongoose magic applied
My variant.
If schema defined with {strict:false} you can simply add new property by
recorcd.newProp = 'newvalue';
If schema defined with {strict:true} you can either convert Mongoose object to object as mentioned earlier or use command
record.set('newProp','newValue',{strict:false})
See http://mongoosejs.com/docs/api.html#document_Document-schema
If you have loaded this object into records, both records.Name = "test" or records['Name'] = "test" will work. You have either not loaded the object correctly, or are inserting an undefined value into it.
To test: add console.log(records.userId), this should print 'test' to the terminal.
Also add console.log(name). If you get ReferenceError: name is not defined, you obviously cannot do: records.Name = name