Category: Medium mongoose populate

medium mongoose populate

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I have a schema structure that is '3 deep' and I find that I can't display information that is at the third level. I'm not sure if it's because this a virtual field, or if I'm doing something wrong. The programme schema looks up the projects like this Which returns the project. My project schema middle level has a virtual field for the outputs collection third levellike so Which works fine when I find and display a single project.

However, when I try and display the documents from the outputs collection at the programme top level, I can't do it. I've tried various different populates, such as I've googled around but aside from one article that I struggled to follow, I can't find anything about this deep populating a virtual field. Learn more. Mongoose deep populate a virtual field Ask Question. Asked 18 days ago. Active 18 days ago.

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Viewed 12 times. Please could someone tell me where I am going wrong? Active Oldest Votes. Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password. Post as a guest Name. Email Required, but never shown. The Overflow Blog. The Overflow How many jobs can be done at home? Featured on Meta.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

The dark mode beta is finally here. Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. A simple await Model. You cannot call populate after you used the lean option. Lean turns the returned objects into regular javascript objects and not mongoose documents.

Populate is a built-in method in mongoose, so you can only use it in mongoose documents. This has nothing to do with your question but it's important to know. When you call exec on a query and pass a callback as parameter, it does not return a promise and therefore the 'await' clause has no effect over it. That's why your function is not waiting for Chat. The following would probably work:. Learn more.

Asked 2 years, 2 months ago. Active 1 year, 2 months ago. Viewed 3k times. Trevor Trevor 2 2 gold badges 9 9 silver badges 27 27 bronze badges. Active Oldest Votes.

Not sure why, tried a lot of different things, but this works. I feel like your code has 2 issues: You cannot call populate after you used the lean option. Felipe Vignon Felipe Vignon 6 6 bronze badges. Sign up or log in Sign up using Google.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

The dark mode beta is finally here. Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. I am trying to populate my users car inventory. All the cars have a userId attached to them when they are created but when I go to populate the inventory it doesn't work and I get no errors.

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#1 Mongoose - deep collections connect with populate

Mongoose populate not populating Ask Question. Asked 3 years, 10 months ago. Active 2 years, 4 months ago. Viewed 3k times. Here are my models: User. Sonicd 1, 1 1 gold badge 12 12 silver badges 20 20 bronze badges. JuniorSauce JuniorSauce 2 2 silver badges 8 8 bronze badges. Active Oldest Votes.

Jack Guy Jack Guy 6, 4 4 gold badges 38 38 silver badges 74 74 bronze badges. Mongo automatically creates that for you when you save to the db.

Are they not linked up the way that I currently have them? JuniorSauce which field from "Car" are you storing in that array?

medium mongoose populate

The inventory field in the User model should be doing that. JuniorSauce, not if you aren't saving the cars in the inventory correctly. Which is what I'd guess the problem is.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. The dark mode beta is finally here. Change your preferences any time.

Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. In Mongoose, I can use a query populate to populate additional fields after a query.

I can also populate multiple paths, such as. However, this would generate a lookup on book gathering the fields for title, pages and director - and also a lookup on movie gathering the fields for title, pages and director as well.

What I want is to get title and pages from books only, and director from movie. I could do something like this:. But is there any way to have the behavior of the second snippet using a similar "single line" syntax like the first snippet?

medium mongoose populate

The reason for that, is that I want to programmatically determine the arguments for the populate function and feed it in. I cannot do that for multiple populate calls. Let's say you have a BookCollection schema which contains users and books In order to perform a query and get all the BookCollections with its related users and books you would do this. Learn more. Mongoose: multiple query populate in a single call Ask Question.

Asked 6 years, 3 months ago. Active 2 years, 2 months ago. Viewed 33k times. I can also populate multiple paths, such as Person. I could do something like this: Person. Se7enDays Se7enDays 2, 2 2 gold badges 10 10 silver badges 19 19 bronze badges. Active Oldest Votes. Ivan 6, 3 3 gold badges 19 19 silver badges 50 50 bronze badges. Kartik Garasia Kartik Garasia 8 8 silver badges 20 20 bronze badges.

Does this kind of usage has any performance impacts against chaining multiple populates? GoncharDenys no, it fails with. Lawrence Edmondson Lawrence Edmondson 6 6 bronze badges. They wanted to select certain data from each one of those paths. Like the book's path they only wanted to populate the title and pages.This combined with multiple lighting distributions, several mounting options, and the ability to tilt the fixture up to 45 degrees offers unequaled performance in a diverse set of area lighting applications.

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Email Selected. Thank you. Recommended Products.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. The dark mode beta is finally here. Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. Firstly populate lets you get a list of user friends. But what if you also wanted a user's friends of friends?

In that case, you can specify a populate option to tell mongoose to populate the friends array of all the user's friends:. As of Mongoose 3. Here is an example of how you might do it:.

In this case, I am populating an array of id's in 'refUserListItems' with their referenced documents. The result of the query then gets passed into another populate query that references the field of the original populated document that I want to also populate - 'refSuggestion'. Note the second internal populate - this is where the magic happens. You can continue to nest these populates and tack on more and more documents until you have built your graph the way you need it.

It takes a little time to digest how this is working, but if you work through it, it makes sense. I'm late to this, but I wrote a Mongoose plugin that makes it extremely simple to perform deep model population. For your example, you can do this to populate b and c :. You can also specify Mongoose populate options for each of the populated paths, like this:.

Check out the plugin documentation for more information.

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Learn more. Mongoose populate embedded Ask Question. Asked 7 years, 5 months ago. Active 4 months ago. Viewed 25k times. I use Mongoose.

There 2 ways to do it. First - without refs. I was try use: A. I was try to use something like this: A. I there way to populate it?Mongoose has a more powerful alternative called populatewhich lets you reference documents in other collections. Population is the process of automatically replacing the specified paths in the document with document s from other collection s.

We may populate a single document, multiple documents, plain object, multiple plain objects, or all objects returned from a query. Let's look at some examples. So far we've created two Models. Our Person model has its stories field set to an array of ObjectId s. The ref option is what tells Mongoose which model to use during population, in our case the Story model.

However, you should use ObjectId unless you are an advanced user and have a good reason for doing so. So far we haven't done anything much different. We've merely created a Person and a Story. Now let's take a look at populating our story's author using the query builder:. Arrays of refs work the same way. You can manually populate a property by setting it to a document.

The document must be an instance of the model your ref property refers to. You can call the populated function to check whether a field is populated. If populated returns a truthy valueyou can assume the field is populated. A common reason for checking whether a path is populated is getting the author id.

Mongoose populate doesn't behave like conventional SQL joins. When there's no document, story. This is analogous to a left join in SQL. If you have an array of authors in your storySchemapopulate will give you an empty array instead.

What if we only want a few specific fields returned for the populated documents? This can be accomplished by passing the usual field name syntax as the second argument to the populate method:.

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If you call populate multiple times with the same path, only the last one will take effect. Populate does support a limit option, however, it currently does not limit on a per-document basis. For example, suppose you have 2 stories:.

medium mongoose populate

If you were to populate using the limit option, you would find that the 2nd story has 0 fans:. If you need the correct limityou should use the perDocumentLimit option new in Mongoose 5. Just keep in mind that populate will execute a separate query for each story. We may find however, if we use the author object, we are unable to get a list of the stories.

This is because no story objects were ever 'pushed' onto author. There are two perspectives here. First, you may want the author know which stories are theirs. Usually, your schema should resolve one-to-many relationships by having a parent pointer in the 'many' side.

But, if you have a good reason to want an array of child pointers, you can push documents onto the array as shown below. It is debatable that we really want two sets of pointers as they may get out of sync. Instead we could skip populating and directly find the stories we are interested in.

The documents returned from query population become fully functional, remove able, save able documents unless the lean option is specified. Do not confuse them with sub docs. Take caution when calling its remove method because you'll be removing it from the database, not just the array.


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