I'm doing the following using Mongoose:
that.model.update({_id: dao._id}, dao, { upsert: true }, cb);
Where dao is a mongoose representation containing (among other things) a couple of embedded documents. As a test I've deleted a couple of the embedded docs from the array before calling the update-method above.
The result is that the change to the array of embedded docs IS NOT persisted.
Anything I'm overlooking?
Hard to be certain w/o seeing more code, but if dao is a Mongoose model instance, you should be calling dao.save(cb); instead.
I solved the problem by doing something similar as proposed in the following issue: https://github.com/LearnBoost/mongoose/issues/571
For completeness some background which led to the problem.
I'm using DDD repositories which are populated on app-start. Under the hood this fetches Mongoose-objects (which are treate as DAOs in my situation) and are translated to domainobjects, which are cached in the repository. I need this separation between domainobjects and mongoose-objects, don't ask.
This means that getById, getAll and all other public interfaces of the repo work with domainobjects and not with mongoose-objects.
When doing things like add or update on the repo this internally only updates the in-mem cache (which, again, only uses domainobjects instead of mongoose-objects)
Only when doing commit on the repo does the possibly changed collection of domainobjects get persisted. This is done by creating NEW Mongoose-objects instead of fetching Existing mongoose-objects and updating those.
This is why I can't use dao.save() since, when I'm saving a different (just created) mongoose-object while a mongoose-object with the same id may possibly already exist in Mongo, it throws a duplicate id error.
Some relevant snippet from by code illustrating the solution:
var dao = that.createDAO(domainobject);
//https://github.com/LearnBoost/mongoose/issues/571
// Convert the Model instance to a simple object using Model's 'toObject' function
// to prevent weirdness like infinite looping...
var upsertData = dao.toObject();
// Delete the _id property, otherwise Mongo will return a "Mod on _id not allowed" error
delete upsertData._id;
that.model.update({_id: dao._id}, upsertData, { upsert: true }, cb);
Related
I recently updated from Wagtail 2.13.5 to 3.0.3. After the update, the search() method on Wagtail's PageQuerySet returns no results for search terms that clearly should return results (and which do when using the older version).
For example, under 2.13, where search_backend is an instance of wagtail.contrib.postgres_search.backend.PostgresSearchBackend, and qs is an instance of wagtail.core.query.PageQuerySet the following returns lots of results:
search_backend.search('popular-search-term', qs, fields=None, operator=None, order_by_relevance=True, partial_match=True)
But under 3.0.3, where search_backend is now an instance of wagtail.search.backends.database.postgres.postgres.PostgresSearchBackend and qs is an instance of wagtail.query.PageQuerySet, the same call to search() will return nothing (an empty queryset).
The data in the qs queryset is the same in both cases, so maybe I'm missing something in my configuration of the search backend? My "settings.py" file has:
WAGTAILSEARCH_BACKENDS = {
'default': {
'BACKEND': 'wagtail.search.backends.database',
'SEARCH_CONFIG': 'english',
},
}
and
INSTALLED_APPS = [
...
'wagtail.search',
'wagtail.search.backends.database.postgres',
...
]
I had to guess at the value for 'wagtail.search.backends.database.postgres'. AFAICT, Wagtail's docs don't mention what should go into INSTALLED_APPS. But the pre-upgrade value of 'wagtail.contrib.postgres_search' would clearly be wrong, as that module has been removed.
Anyone got an idea why calling search() on a PageQuerySet would incorrectly return no results?
The steps for changing the search backend are documented at https://docs.wagtail.org/en/stable/releases/2.15.html#database-search-backends-replaced. In particular:
You should remove wagtail.contrib.postgres_search from INSTALLED_APPS, and do not need to add anything in its place - the existing wagtail.search app is sufficient
After changing over, you need to re-run the ./manage.py update_index command to ensure that the new search index is populated.
I am attempting to use pre('findOneAndUpdate') to update the icon attribute of the Meeting document. The update is based on the pre-existing value of the yearlymeeting attribute (see below).
Because pre and post save() hooks are not executed on update(), I seem to be unable to access the original document at all. Yet this is critical for the operation I'm trying to perform. Is there any way around this?
For example, I am able to accomplish my purpose on pre('save'), like so:
meetingSchema.pre('save', function(next) {
const yearlymeetingSlug = this.yearlymeeting[0].toLowerCase().replace(/[^A-z0-9]/g, '');
this.icon = `${yearlymeetingSlug}.png`
next();
});
What I would like to be able to do is something like this:
meetingSchema.pre('findOneAndUpdate', function(next) {
const yearlymeetingSlug = originalDocument.yearlymeeting[0].toLowerCase().replace(/[^A-z0-9]/g, '');
this.icon = `${yearlymeetingSlug}.png`
next();
});
I understand that this in pre(findOneAndUpdate) refers to the query, rather than the stored document itself. Is there any way to access the document, so that I can update icon based on the stored value of yearlymeeting?
tl;dr
Not possible via middleware. Query for the doc first, and then separately update a specific version of the doc to prevent race conditions.
Can't do it the way you're trying according to this issue on the Mongoose Github (from the main dev):
By design - the document being updated might not even be in the server's memory. In order to do that, mongoose would have to do a findOne() to load the document before doing the update(), which is not acceptable.
The design is to enable you to manipulate the query object by adding or removing filters, update params, options, etc. For instance, automatically calling .populate() with find() and findOne(), setting the multi: true option by default on certain models, access control, and other possibilities.
findOneAndUpdate() is a bit of a misnomer, it uses the underlying mongodb findAndModify command, it's not the same as findOne() + update(). As a separate operation, it should have its own middleware.
Following this, there are no other suggestions in the issue thread to access the original document inside of the middleware itself.
What I've seen done (and what I've had to do many times myself), is simply have to query for the document before updating it (which, of course, could lead to a race condition depending on who is updating the doc, and when, but you can fix that by also querying for a specific version of the document -- a sort of "optimistic locking"):
let meeting = yield Meeting.findOne({}).exec()
let update = {}
// ... some conditional logic to figure out which icon to set
update.icon = // whatever
yield Meeting.update({ _id: meeting._id, version: meeting.version }, update)
This is of course assuming you have a "version" field in your schema. This sort of locking will prevent you from updating an old version of the doc. If you're gonna use this kind of versioning, you'll also probably want to add some middleware that updates the version of a doc any time the doc is updated/saved.
You can also use a more naïve implementation, where you don't use locking, which may be fine in your specific business case, as long as you're aware of the possibility of a race condition, and the risks.
This may not be the best solution, but I did find a way to make it work. I used the controller rather than schema pre hooks. Here's what my update controller looks like now:
exports.updateMeeting = async (req, res) => {
const _id = req.params.id
let meeting = await Meeting.findOneAndUpdate({ _id }, req.body, {
new: true,
runValidators: true
});
/* New Code: */
const yearlymeetingSlug = meeting.yearlymeeting[0].toLowerCase().replace(/[^A-z0-9]/g, '');
meeting.icon = `${yearlymeetingSlug}.png`;
meeting.save();
req.flash('success', 'meeting successfully updated!');
res.redirect(`/meetings/${meeting.slug}`);
};
I welcome your feedback on any problems you see with this solution.
I want to create a backend service which monitors a mongodb collection for new entries. As those are being created, I wish to run processing and update them.
I thought doing so with a Meteor service/app would be a wise idea because Meteor uses 'oplog tailing' which seems ideal for this purpose (I'd rather avoid polling if possible).
As such, I figured creating a minimal server-side-only app should solve it.
So basically, I need something along these lines:
if (Meteor.isServer) {
MyCollection = new Mongo.Collection('myCollection');
Meteor.publish('myCollectionPub', function () {
return MyCollection.find({ some: criteria... });
}
// is there such a thing?
Meteor.serverSideSubscribe('MyCollectionPub',
function (newDocs) {
// process/update newDocs
});
}
According to the Meteor docs, I cannot use Meteor.subscribe() on the server (and indeed it crashes if I try).
Question is:
Are there ways of 'subscribing' to collection updates on the server?
The PeerLibrary server-autorun package (along with it's dependant, reactive-mongo) will provide you with easy server-side observation of collections.
An alternative to #tarmes suggestion is the collection-hooks package, however as pointed out by David Weldon, it will only trigger in instance it is run in:
https://github.com/matb33/meteor-collection-hooks
MyCollection.after.insert(function (userId, doc) {
// ...
});
If you need it to run even when another instance makes a change in the mongo database, you can observe a cursor that is returned from your collection:
MyCollection.find({created_at : {$gt: some_current_time}}).observe({
added: function(item) {
// Alert code
}
});
My question is this: How can you implement a default server-side "filter" for a navigation property?
In our application we seldom actually delete anything from the database. Instead, we implement "soft deletes" where each table has a Deleted bit column. If this column is true the record has been "deleted". If it is false, it has not.
This allows us to easily "undelete" records accidentally deleted by the client.
Our current ASP.NET Web API returns only "undeleted" records by default, unless a deleted argument is sent as true from the client. The idea is that the consumer of the service doesn't have to worry about specifying that they only want undeleted items.
Implementing this same functionality in Breeze is quite simple, at least for base entities. For example, here would be the implementation of the classic Todo's example, adding a "Deleted" bit field:
// Note: Will show only undeleted items by default unless you explicitly pass deleted = true.
[HttpGet]
public IQueryable<BreezeSampleTodoItem> Todos(bool deleted = false) {
return _contextProvider.Context.Todos.Where(td => td.Deleted == deleted);
}
On the client, all we need to do is...
var query = breeze.EntityQuery.from("Todos");
...to get all undeleted Todos, or...
var query = breeze.EntityQuery.from("Todos").withParameters({deleted: true})
...to get all deleted Todos.
But let's say that a BreezeSampleTodoItem has a child collection for the tools that are needed to complete that Todo. We'll call this "Tools". Tools also implements soft deletes. When we perform a query that uses expand to get a Todo with its Tools, it will return all Tools - "deleted" or not.
But how can I filter out these records by default when Todo.Tools is expanded?
It has occurred to me to have separate Web API methods for each item that may need expanded, for example:
[HttpGet]
public IQueryable<Todo> TodoAndTools(bool deletedTodos = false, bool deletedTools = false)
{
return // ...Code to get filtered Todos with filtered Tools
}
I found some example code of how to do this in another SO post, but it requires hand-coding each property of Todo. The code from the above-mentioned post also returns a List, not an IQueryable. Furthermore this requires methods to be added for every possible expansion which isn't cool.
Essentially what I'm looking for is some way to define a piece of code that gets called whenever Todos is queried, and another for whenever Tools is queried - preferably being able to pass an argument that defines if it should return Deleted items. This could be anywhere on the server-side stack - be it in the Web API method, itself, or maybe part of Entity Framework (note that filtering Include extensions is not supported in EF.)
Breeze cannot do exactly what you are asking for right now, although we have discussed the idea of allowing the filtering of "expands", but we really need more feedback as to whether the community would find this useful. Please add this to the breeze User Voice and vote for it. We take these suggestions very seriously.
Moreover, as you point out, EF does not support this.
But... what you can do is use a projection instead of an expand to do something very similar:
public IQueryable<Object> TodoAndTools(bool deleted = false
,bool deletedTools = false) {
var baseQuery = _contextProvider.Context.Todos.Where(td => td.Deleted == deleted);
return baseQuery.Select(t => new {
Todo: t,
Tools: t.Tools.Where( tool => tool.Deleted = deletedTools);
});
}
Several things to note here:
1) We are returning an IQueryable of Object instead of IQueryable of ToDo
2) Breeze will inspect the returned payload and automatically create breeze entities for any 'entityTypes' returned (even within a projection). So the result of this query will be an array of javascript objects each with two properties; 'ToDo' and 'Tools' where Tools is an array of 'Tool' entities. The nice thing is that both ToDo and Tool entities returned within the projection will be 'full' breeze entities.
3) You can still pass client side filters based on the projected property names. i.e.
var query = EntityQuery.from("TodoAndTools")
.where("Todo.Description", "startsWith", "A")
.using(em);
4) EF does support this.
using the unit of work and repository patterns i recently came across the issue, that changes to the unit of work are not reflected to subsequent queries. Example:
var ctx = DIContainer.Current.Resolve<IB2bContext>();
var rep = DIContainer.Current.Resolve<IRepository<Word>>(
new DependencyOverride<IB2bContext>(ctx));
rep.Add(new Word () { "One" };
rep.Add(new Word () { "Two" };
rep.GetAll().ToList().ForEach(i =>
Console.Write(i.text)); // nothing seen here
So in other words, unless i call SaveChanges() to persist the objects into the Database, i dont see them. Well ofcause i can fiddle around with the ChangeTracker and/or do things like context.Entry(foo).Property(...).CurrentValue. But does that play with a ddd like decoupling of layers? I dont think so. And where is my consistent dataview that once was called a database transaction?
Please enlighten me.
Armin
Your repository exposes some GetAll method. The method itself executes database query. If you want to see local data not inserted to database you must add them to result set. For example like:
public IEnumerable<Word> GetAll()
{
DbSet<Word> set = context.Set<Word>();
return set.AsEnumerable().Concat(set.Local);
}
The query execution is only responsible for returning persisted (real) data.