I want to know what the 'clean' value of a dirty prop is in a pre-save mongoose hook like this:
UserSchema.pre('save', function(next) {
var user = this;
if (user.isModified('password')){
//i want to know what the value of user.password was before it was changed
}
next()
}
Is it possible to look up the old value without looking it up in the db?
By default, the old values are not stored. You would have to do is track the old data with a post init hook (a mongoose feature).
What we do is attach copy of the original document to all items pulled from MongoDB. We have this code for each schema we need to get pre-dirty data for comparison:
schema.post( 'init', function() {
this._original = this.toObject();
} );
NodeJS is pretty efficient, and does copy on write when possible, so you don't see double the memory consumption unless you modify the entire document. Only then does _original actually consume double the memory.
So in a pre-save hook, from what I can tell by reading this section of the source code, I don't think the previous value is stored anywhere. So you'll have to load the document from mongodb to get it.
However, you might want to use the virtuals mechanism instead of a pre-save hook to store the old value before changing it to the new value.
var virtual = schema.virtual('password');
virtual.set(function (v) {
var this._oldPassword = this.password;
return v;
});
Experiment with something along those lines and see if you can make something work suitably.
Related
I am using graphql to get some data from mongodb database. So, I was making an api which on running saves data in main collection but also saves data in some other collection with a couple of more data. I was trying to delete _id from the data that I get on saving on main collection but it's not working and I can't figure out why.
Here's what's happening
const data = await User.getResolver('updateById').resolve({ //default resolver from graphql-compose library to update a record. Returns the whole document in record //
args: {...rp.args}
})
const version = '4'
const NewObject = _.cloneDeep(data.record);
NewObject.version = version;
NewObject.oldId = data._id;
_.unset(NewObject, '_id'); //this doesn't work neither does delete NewObject._id//
console.log('new obj is', NewObject, version, NewObject._id, _.unset(NewObject, '_id')); //prints _id and surprisingly the unset in console.log is returning true that means it is successfully deleting the property//
I am very confused to what I am doing wrong.
Edit: Sorry should have mentioned, but according to lodash docs _.unset returns true if it successfully deletes a property.
Turn's out mongoDb makes _id as a Non configurable property. So, to do this I had to make use of toObject() method to make an editable copy of my object.
const NewObject = _.cloneDeep(data.record).toObject();
With this I was able to delete _id.
Alternatively _.omit of lodash also works.
I have been trying to run a custom validator to check if the name entered by the user already exists in the database. Since, mongoDb treats uppercase and lowercase names as different, I created my own validator for it.
function uniqueFieldInsensitive ( modelName, field ){
return function(val, cb){
if( val && val.length ){ // if string not empty/null
var query = mongoose.models[modelName]
.where( field, new RegExp('^'+val+'$', 'i') ); // lookup the collection for somthing that looks like this field
if( !this.isNew ){ // if update, make sure we are not colliding with itself
query = query.where('_id').ne(this._id)
}
query.count(function(err,n){
// false when validation fails
cb( n < 1 )
})
} else { // raise error of unique if empty // may be confusing, but is rightful
cb( false )
}
}
}
Now, the problem is that the validator runs while saving the document in the DB but not while update.
Since, I am using mongoose version 4.x, I also tried using { runValidators: true } in my update query. That doesn't work either as the 'this' keyword in my validator is 'null' while in the case of update whereas it refers to the updated doc in the case of save.
Could you please let me know if there is something i missed or is there any other way by which I can run custom validators in update query.
Finally I found a way out to do this.
According to MongoDB documentation, it says:
First, update validators only check $set and $unset operations. Update validators will not check $push or $inc operations.
The second and most important difference lies in the fact that, in document validators, this refers to the document being updated. In the case of update validators, there is no underlying document, so this will be null in your custom validators.
Refer to : Validators for update()
So, now we are only left with calling save() instead of update() in our queries. Since, save() calls all the custom and inbuilt validators, our validator will also be called. I achieved it like this:
function(req, res, next) {
_.assign(req.libraryStep, req.body);
req.libraryStep.save().then(function(data){
res.json(data);
}).then(null, function (err) {
console.info(err);
var newErr = new errorHandler.error.ProcessingError(errorHandler.getErrorMessage(err));
next(newErr);
});
};
Notice here req.libraryStep is the document that i queried from the database. I have used lodash method assign which takes the updated json and assigns it to the existing database document.
https://lodash.com/docs#assign
I dont think this is the ideal way but as for now till Mongoose doesnt come up with supporting custom validators, we can use this to solve our problem.
This is a fairly old thread, but I wanted to update the answer for those who come across it like I did.
While you're correct about the context of this being empty in an update validator (per the docs), there is a context option you can use to set the context of this. See the docs
However, a plugin also exists that will check the uniqueness of the field you are setting: mongoose-unique-validator. I use this for checking for duplicate emails. This also has an option for case insensitivity, so I would check it out. It also does run correctly using the update command with the runValidators: true option.
I want to get the value of an object before the pre-save hook and compare that to the new value. As suggested in mongoose get db value in pre-save hook and https://github.com/Automattic/mongoose/issues/2952, I did a post-init hook that copied it to a doc._original. The issue is that I'm not sure how to access this ._original in a different hook.
FieldSchema
.post('save', function (doc) {
console.log(doc._original);
});
FieldSchema
.post('init', function (doc) {
doc._original = doc.toObject();
});
I know that the doc in the post save hook is different from the doc in the post init hook, but how would I access the original?
You can only access properties on a database which you have defined in its schema. So since you probably haven't defined _original as a property in your schema, you can't access, or even set it.
One way would be to obviously define _original in your schema.
But to get and set properties not defined in your schema: use .get, and .set with {strict:false}
FieldSchema
.post('save', function (doc) {
console.log(doc.get('_original'));
});
FieldSchema
.post('init', function (doc) {
doc.set('_original', doc.toObject(), {strict: false});
});
Note the option {strict: false} passed to .set which is required because you're setting a property not defined in the schema.
update:
First thing I didn't notice before is that in your question title you want pre-save hook but in your code you actually have a post-save hook (which is what I based my answer on). I hope you know what you're doing, in that post save hook is invoked after saving the document.
But in my opinion, and from what I can understand what your original intent was from the question, I think you should actually use a pre-save hook and an async version of it (by passing next callback), so that you can .find (retrieve) the document from the database, which would be the original version since the new version hasn't yet been saved (pre-save) thus enabling you to compare without actually saving any new fields, which seems an anti-pattern to begin with.
So something like:
FieldSchema
.pre('save', function (next) {
var new_doc = this;
this.constructor // ≈ mongoose.model('…', FieldSchema).findById
.findById(this.id, function(err, original){
console.log(original);
console.log(new_doc);
next();
});
});
http://mongoosejs.com/docs/middleware.html
I'm trying to override the _id field of a mongo doc to an integer with an auto inc.
I've tried some modules and none of them worked for me. I thought I'd write something of my own, like this :
productSchema.pre('save', function (next) {
this._id = 5; //or what ever
next();
});
but it didn't work and the _id field was null. Even tried this._doc['id'] = 5. I thought in merging the _id to the doc before it was saved by a redis but that's ugly since the redis.get is async so I'd have to pass the save action inside the redis callback.
Any solutions?
I have User schema which has a username field. I would like this field to be case sensitive, so that users may register names such as BobDylan. However, I need my schema to validate new entries to check there are no duplicates, incase sensitive, such as bobdylan.
My research has taught me that I should create an additional field in the schema for storing a lower case / upper case version, so that I can easily check if it is unique. My question is, how would I achieve this with the Mongoose API?
I have tried using a set function, such as:
UserSchema.path('username_lower_case').set(function(username_lower_case) {
return this.username.toLowerCase()
});
However, this function doesn't seem to be running. I basically need to tell username_lower_case to be whatever username is, but in lower case.
One way would be to use a pre-save hook to do it.
UserSchema.pre('save', function (next) {
this.username_lower_case = this.username && this.username.toLowerCase();
next();
});
Another way would be to make username a virtual:
UserSchema.virtual('username').set(function (value) {
this.username_raw = value;
this.username_lower_case = value && value.toLowerCase();
}).get(function () {
return this.username_raw;
});