Subdocuments are documents embedded in other documents. In Mongoose, this means you can nest schemas in other schemas. Mongoose has two distinct notions of subdocuments: arrays of subdocuments and single nested subdocuments. Aside from code reuse, one important reason to use subdocuments is to create a path where there would otherwise not be one to allow for validation over a group of fields e. Subdocuments are similar to normal documents. Nested schemas can have middlewarecustom validation logicvirtuals, and any other feature top-level schemas can use.

The major difference is that subdocuments are not saved individually, they are saved whenever their top-level parent document is saved. Subdocuments have save and validate middleware just like top-level documents.

Calling save on the parent document triggers the save middleware for all its subdocuments, and the same for validate middleware. Subdocuments' pre 'save' and pre 'validate' middleware execute before the top-level document's pre 'save' but after the top-level document's pre 'validate' middleware. This is because validating before save is actually a piece of built-in middleware. MongooseArray methods such as pushunshiftaddToSetand others cast arguments to their proper types transparently:.

Subdocs may also be created without adding them to the array by using the create method of MongooseArrays. Each subdocument has it's own remove method. For an array subdocument, this is equivalent to calling. For a single nested subdocument, remove is equivalent to setting the subdocument to null. Sometimes, you need to get the parent of a subdoc. You can access the parent using the parent function. If you have a deeply nested subdoc, you can access the top-level document using the ownerDocument function.

If you create a schema with an array of objects, mongoose will automatically convert the object to a schema for you:.The examples on this page use the inventory collection.

To populate the inventory collection, run the following:. Populate the inventory collection with the following documents:. The driver provides com. Filters helper methods to facilitate the creation of filter documents. The examples on this page use these methods to create the filter documents.

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Copy the following filter into the Compass query bar and click Find :. For example, the following query does not match any documents in the inventory collection:.

When querying using dot notation, the field and nested field must be inside quotation marks. The following example selects all documents where the field uom nested in the size field equals "in" :. A query filter document can use the query operators to specify conditions in the following form:. In addition to the equality condition, MongoDB provides various query operators to specify filter conditions.

Use the com. For example:. In addition to the equality filter, MongoDB provides various query operators to specify filter conditions. Use the FilterDefinitionBuilder methods to create a filter document. The following query selects all documents where the nested field h is less than 15the nested field uom equals "in"and the status field equals "D" :. Tip The driver provides com. Subdocument key order matters in a few of these examples so we have to use bson. SON instead of a Python dict.

InsertMany documents. Subdocument key order matters in this example so we have to use Tie::IxHash instead of a regular, unordered Perl hash. InsertMany context. Backgrounddocs. Copy the following filter into the Compass query bar and click Find : copy.

Find filter. ToList. Find context. Backgroundbson. Note When querying using dot notation, the field and nested field must be inside quotation marks. Eq "size.

A query filter document can use the query operators to specify conditions in the following form: copy. For example: copy. Filter ; builder. And builder.This page provides examples of query operations on an array of nested documents using the db. The examples on this page use the inventory collection. To populate the inventory collection, run the following:.

This page provides examples of query operations on an array of nested documents using MongoDB Compass. Populate the inventory collection with the following documents:. This page provides examples of query operations on an array of nested documents using the pymongo. This page provides examples of query operations on an array of nested documents using the com. The driver provides com. Filters helper methods to facilitate the creation of filter documents.

The examples on this page use these methods to create the filter documents. This page provides examples of query operations on an array of nested documents using the Collection. This page provides examples of query operations on an array of nested documents using the motor. This page provides examples of query operations on an array of nested documents using the MongoCollection. This page provides examples of query operations on an array of nested documents using the Mongo::Collection find method in the MongoDB Ruby Driver.

This page provides examples of query operations on an array of nested documents using the collection. The following example selects all documents where an element in the instock array matches the specified document:. Copy the following filter into the Compass query bar and click Find :.

For example, the following query does not match any documents in the inventory collection:. If you do not know the index position of the document nested in the array, concatenate the name of the array field, with a dot. The following example selects all documents where the instock array has at least one embedded document that contains the field qty whose value is less than or equal to 20 :.

Using dot notationyou can specify query conditions for field in a document at a particular index or position of the array. The array uses zero-based indexing. When querying using dot notation, the field and index must be inside quotation marks.

The following example selects all documents where the instock array has as its first element a document that contains the field qty whose value is less than or equal to 20 :. When specifying conditions on more than one field nested in an array of documents, you can specify the query such that either a single document meets these condition or any combination of documents including a single document in the array meets the conditions.

The following example queries for documents where the instock array has at least one embedded document that contains both the field qty equal to 5 and the field warehouse equal to A :.

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The following example queries for documents where the instock array has at least one embedded document that contains the field qty that is greater than 10 and less than or equal to 20 :.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:. 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:.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

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mongoose query subdocument

Question is, how to fetch all subdocuments in this case, childrenSchema objects from every parent document? Let's suppose I have some data:. I would like to retrieve - in a single query - all children older than Is it possible? Every answer will be appreciated, thanks! From the mongo shell:. As you can see, children are still grouped inside their parent documents. MongoDB queries return documents from collections. In Mongoose, you can also use the elegant. Jesse Jiryu Davis's response works like a charm, however for later versions of Mongoose Mongoose 5.

Mongoose 5. Instead of Model. Learn more.

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Mongoose - finding subdocuments by criteria Ask Question. Asked 6 years, 10 months ago. Active 10 months ago.

mongoose query subdocument

Viewed 41k times. I've just got stuck with this problem. Nuri Tasdemir 8, 2 2 gold badges 30 30 silver badges 52 52 bronze badges. Kuba T Kuba T 1, 2 2 gold badges 16 16 silver badges 26 26 bronze badges. Do you want it to only return the parent if the child is over 18 or do you want it to only populate the children that are over 18 on each parent?

It would be great if I get the set of "children" Active Oldest Votes. From the mongo shell: db. Jesse Jiryu Davis A.FInding sub-docs in mongoose the first time may seem a bit hard or just confusing.

That's why I decided to write this. As you can see we embedded the likesSchema inside the statusSchema which is embedded inside the userSchema. The problem with sub-docs is that they are not saved individually, they are saved there the parent Schema is saved, so if you need to use the sub-docs individually this may not be the right approach for you.

This will create two users. After this comes the interesting part: Querying the sub-docs, creating them and modifying them. As well with the sub-sub-docs. This is were trouble comes, because there is not really a way in mongoose to query them. You can use the position in the array if you know it, but you can't really keep track of this. August 09, Last Updated: August 09, Querying sub-documents and sub-sub-documents in Mongoose nodejs express expressjs mongodb mongoose express.

Query sub-sub-docs This is were trouble comes, because there is not really a way in mongoose to query them. Remember it is an array so you can do this to query them: for i in subdoc. December 29, How do you go about updating a subdocument given the parent id and the child id?

February 03, March 10, November 12, I exactly did what has been mentioned, but seems to have an error. Thanks in advance. November 20, Sponsored by.

Filed Under Node. Awesome Job. See All Jobs.Mongoose models provide several static helper functions for CRUD operations. Each of these functions returns a mongoose Query object. A mongoose query can be executed in one of two ways. First, if you pass in a callback function, Mongoose will execute the query asynchronously and pass the results to the callback.

When executing a query with a callback function, you specify your query as a JSON document. Mongoose executed the query and passed the results passed to callback. All callbacks in Mongoose use the pattern: callback error, result.

If an error occurs executing the query, the error parameter will contain an error document, and result will be null. If the query is successful, the error parameter will be null, and the result will be populated with the results of the query. Anywhere a callback is passed to a query in Mongoose, the callback follows the pattern callback error, results.

What results is depends on the operation: For findOne it is a potentially-null single documentfind a list of documentscount the number of documentsupdate the number of documents affectedetc. The API docs for Models provide more detail on what is passed to the callbacks. In the above code, the query variable is of type Query. The below 2 examples are equivalent.

A full list of Query helper functions can be found in the API docs.

mongoose query subdocument

Mongoose queries are not promises. They have a.

Querying sub-documents and sub-sub-documents in Mongoose

However, unlike promises, calling a query's. For example, the below code will execute 3 updateMany calls, one because of the callback, and two because. Don't mix using callbacks and promises with queries, or you may end up with duplicate operations.

There are no joins in MongoDB but sometimes we still want references to documents in other collections. This is where population comes in.