I have a database filled with classes and I want to be able to find all of the classes that match the subject code and the course number provided.
course_number = ['2920', '3100', '3200', '3300', '3500', '4100', '4200', '4300', '4310', '4400', '4500']
for doc in db.all_classes.find(
{"class_schedule.subject_code": "CSCI" },
{ "class_schedule.course_number": { '$elemMatch': { course_number } } } ):
print doc
Related
I have a database like this:
[
{
"universe":"comics",
"saga":[
{
"name":"x-men",
"characters":[
{
"character":"wolverine",
"picture":"618035022351.png"
},
{
"character":"cyclops",
"picture":"618035022352.png"
}
]
}
]
},
{
"universe":"dc",
"saga":[
{
"name":"spiderman",
"characters":[
{
"character":"venom",
"picture":"618035022353.png"
}
]
}
]
}
]
and with this code I manage to update one of the objects in my array. specifically the object where character: wolverine
db.mydb.findOneAndUpdate({
"universe": "comics",
"saga.name": "x-men",
"saga.characters.character": "wolverine"
}, {
$set: {
"saga.$[].characters.$[].character": "lobezno",
"saga.$[].characters.$[].picture": "618035022354.png",
}
}, {
new: false
}
)
it returns all my document, I need ONLY the document matched
I would like to return the object that I have updated without having to make more queries to the database.
Note
I have been told that my code does not work well as it should, apparently my query to update this bad, I would like to know how to fix it and get the object that matches these search criteria.
In other words how can I get this output:
{
"character":"wolverine",
"picture":"618035022351.png"
}
in a single query using filters
{
"universe": "comics",
"saga.name": "x-men",
"saga.characters.character": "wolverine"
}
My MongoDB knowledge prevents me from correcting this.
Use the shell method findAndModify to suit your needs.
But you cannot use the positional character $ more than once while projecting in MongoDb, so you may have to keep track of it yourself at client-side.
Use arrayFilters to update deeply nested sub-document, instead of positional all operator $[].
Below is a working query -
var query = {
universe: 'comics'
};
var update = {
$set: {
'saga.$[outer].characters.$[inner].character': 'lobezno',
'saga.$[outer].characters.$[inner].picture': '618035022354.png',
}
};
var fields = {
'saga.characters': 1
};
var updateFilter = {
arrayFilters: [
{
'outer.name': 'x-men'
},
{
'inner.character': 'wolverine'
}
]
};
db.collection.findAndModify({
query,
update,
fields,
arrayFilters: updateFilter.arrayFilters
new: true
});
If I understand your question correctly, your updating is working as expected and your issue is that it returns the whole document and you don't want to query the database to just to return these two fields.
Why don't you just extract the fields from the document returned from your update? You are not going to the database when doing that.
var extractElementFromResult = null;
if(result != null) {
extractElementFromResult = result.saga
.filter(item => item.name == "x-men")[0]
.characters
.filter(item => item.character == "wolverine")[0];
}
I have a situation where a model changed at some point in time and I am faced with (for argument sake) half my data liks like this
{
_id: OID,
things: [{
_id:OID,
arm: string,
body: string
}],
other: string
}
and the other half of my data look like this
{
_id: OID,
things: [{
_id:OID,
upper_appendage: string,
body: string
}],
other: string
}
I would like to 'correct' half of the data - so that I DON'T have to accommodate both names for 'arm' in my application code.
I have tried a couple different things:
The first errors
db.getCollection('x')
.find({things:{$exists:true}})
.forEach(function (record) {
record.things.arm = record.things.upper_appendage;
db.users.save(record);
});
and this - which destroys all the other data in
db.getCollection('x')
.find({things:{$exists:true}})
.forEach(function (record) {
record.things = {
upper_appendage.arm = record.things.upper_appendage
};
db.users.save(record);
});
Keeping in mind that there is other data I want to maintain...
How can I do this???
the $rename operator should have worked for this job but unfortunately it doesn't seem to support nested array fields (as of mongodb server 4.2). instead you'd need a forEach like the following:
db.items.find({
things: {
$elemMatch: {
arm: {
$exists: true
}
}
}
}).forEach(function(item) {
for (i = 0; i != item.things.length; ++i)
{
item.things[i].upper_appendage = item.things[i].arm;
delete item.things[i].arm; ;
}
db.items.update({
_id: item._id
}, item);
})
note: i've assumed you want to make all records have upper_appendageand get rid of 'arm' field. if it's the other way you want, just switch things around.
In my Movie schema, I have a field "release_date" who can contain nested subdocuments.
These subdocuments contains three fields :
country_code
date
details
I need to guarantee the first two fields are unique (primary key).
I first tried to set a unique index. But I finally realized that MongoDB does not support unique indexes on subdocuments.
Index is created, but validation does not trigger, and I can still add duplicates.
Then, I tried to modify my update function to prevent duplicates, as explained in this article (see Workarounds) : http://joegornick.com/2012/10/25/mongodb-unique-indexes-on-single-embedded-documents/
$ne works well but in my case, I have a combination of two fields, and it's a way more complicated...
$addToSet is nice, but not exactly what I am searching for, because "details" field can be not unique.
I also tried plugin like mongoose-unique-validator, but it does not work with subdocuments ...
I finally ended up with two queries. One for searching existing subdocument, another to add a subdocument if the previous query returns no document.
insertReleaseDate: async(root, args) => {
const { movieId, fields } = args
// Searching for an existing primary key
const document = await Movie.find(
{
_id: movieId,
release_date: {
$elemMatch: {
country_code: fields.country_code,
date: fields.date
}
}
}
)
if (document.length > 0) {
throw new Error('Duplicate error')
}
// Updating the document
const response = await Movie.updateOne(
{ _id: movieId },
{ $push: { release_date: fields } }
)
return response
}
This code works fine, but I would have preferred to use only one query.
Any idea ? I don't understand why it's so complicated as it should be a common usage.
Thanks RichieK for your answer ! It's working great.
Just take care to put the field name before "$not" like this :
insertReleaseDate: async(root, args) => {
const { movieId, fields } = args
const response = await Movie.updateOne(
{
_id: movieId,
release_date: {
$not: {
$elemMatch: {
country_code: fields.country_code,
date: fields.date
}
}
}
},
{ $push: { release_date: fields } }
)
return formatResponse(response, movieId)
}
Thanks a lot !
I have Mongoose schema like this:
{
......
project: [
{
Name: String,
Criteria:[
{
criteriaName:String,
}
]
}
]
......
}
And I want to remove one of the objects of criteria array which is in the array of project based on the object id
I tried the code following
criteria.findOneAndUpdate({
"_id": uid,
},{ $pull: { "project.Criteria": { _id: cid } } }, (err) => {
......
}
However this cannot work, it said "Cannot use the part (Criteria) of (project.Criteria) to traverse the element"
Do you need to do it in one query to the database? If not, the following solution may work for you:
criteria.findOne({ _id: uid })
.then((obj) => {
// Filter out the criteria you wanted to remove
obj.project.Criteria = obj.project.Criteria.filter(c => c._id !== cid);
// Save the updated object to the database
return obj.save();
})
.then((updatedObj) => {
// This is the updated object
})
.catch((err) => {
// Handle error
});
Sorry if the .then/.catch is confusing. I can rewrite with callbacks if necessary, but I think this looks a lot cleaner. Hope this helps!
Here's the structure part of my collection :
{
_id: {
id:"6a6ca923517f304900badd98",
target:"00badd6a6ca923517f304998e4df"
},
...
}
The use of :
if(bson_find(iterator, mongo_cursor_bson(cursor), "_id")){
bson_iterator_subiterator(iterator, sub);
id = (char*)bson_iterator_string(sub);
}
is "working" but in reality simply returns me the result of the first field of the array found...
How to recover precisely the value of the "id" or "target" field please ?
You can also use bson_iterator_more and bson_iterator_next upon the sub-iterator(It was still an iterator).
try this:
if(bson_find(iterator, mongo_cursor_bson(cursor), "_id"))
{
bson_iterator_subiterator(iterator, sub);
while(bson_iterator_more(sub))
{
if (bson_iterator_next(sub) != BSON_EOO)
{
printf("%s: %s\n", bson_iterator_key(sub), bson_iterator_string(sub));
}
}
}