how to Remove given list of documents from mongodb collection? eg:
i want to remove list of students which name containing empty value like.
var list=db.Student.find({'Name': {$eq: ''}})
db.Student.update($pull:{list})
but its is not working. is there any other best solution for this?
You can remove the documents with the given condition by passing a query document. Try this;
db.Student.remove( { Name : "" } )
You can refer this link for further clarifications.
http://docs.mongodb.org/manual/tutorial/remove-documents/
db.Student.remove({'Name':''})
Check the docs
Related
I'm new to MongoDB and Meteor. I have checked the official docs but seems they didn't do good job. Here I have couple of questions.
The structure is as follows.
{
_id:"127467812649871246",
"name":"Disha",
"last_name":"shukla",
"members":
[
{
name:"xyz"
},
{
name:"abc"
}
],
"user":"premium"
}
1] How to insert data in particular field when the data is already exists by referring the record ID ? In this case, insert a new member in "Members"
2] In some cases there wont be "user":"premium" field. Because I wont insert at first time. How do I check if that field is exists if I have inserted for some document ?
Any help will be appreciated :)
Thank you!
The $push command is used to insert data into an existing array in MongoDB. And $exists is used to check whether a field exists in a collection. Go to the links to find more.
1) You can use update by some selector, for example by name
CollectionName.update({name:"Disha"}, {$push: {members: {name: "new"}}})
2) If you want to check if the field exists use this
CollectionName.find({user: {$exists:true}}).
If you want to check if user is premium
CollectionName.find({user: "premium"}).
If you want to check both:
CollectionName.find({$and: [{user: {$exists:true}}, {user: "premium"}]})
Apologies if this is a re-post, but I wasn't able to quite get the query I want from the mongodb documentation examples.
Here's my issue. I am unable execute in a single query to either update an array_field of an existing document or add a new document and initialize the array_field with an initial value.
I can use findOne() with some conditional logic, and probably solve this, but I would think mongodb has an implementation of this use case
Here's the code so far:
#data_json = JSON document to be added to collection
collection.update_one({"json_id":data_json["json_id"], "_dashbd_id_":dashboard_id},{{"$addToSet": {"array_field":keyword}},{"$setOnInsert":data_json}}, upsert=True)
I'm querying by the json_id, and _dashbd_id_ from my collection. If it exists, then I intend to add the "keyword" to the array_field. If it doesn't exist, create a new document as data_json which include array_field = [keyword]
Any hints and suggestions are appreciated!
If I understood you correctly you want to update values in Database only if they do not exist as well as create new documents with arrays in them. Okay there is a way in mongodb which I will mention in this reply. I think you should know few commands first that will help you achieve similar result (again there is a simple way just read on)
Let me start with the first part:
to update an element in an array you use dot notation to the index example:
db.collection_name.update({"_id": id}, {'$set': {"array_name.indexNumber": value}})
say we have the following document in collection name cars
db.cars.findOne():
{
_id: 1
name: EvolutionX
brand: Mitsubish
year: 2012
mods: [ turbo, headlights ]
}
Say in the above example we want to update headlights with rearlights we do the following (using mongoshell you can drop quotes in key names, Not when using the array index though):
db.cars.update({id:1}, {$set:{"mods.1":"rearlights"}})
1 is the index to headlights.
Note and be careful here that if you did not use index inside of an array like
db.cars.update({id:1}, {$set:{"mods":"rearlights"}})
this will overwrite the existing document _id:1 and it will lose all other attributes or fields inside the document so it will result in the follow:
db.cars.findOne():
{
_id: 1
mods: [ rearlights ]
}
Now, say we want to add an element tires to mods array you can use $push as:
db.collection_name.update({"_id": id}, {'$push': {"array_name": value}})
so it will be
db.cars.update({"_id":1}, {"$push":{"mods":"tires"}})
now say instead of updating mods array you want to remove "headlights". In this case you use $pop
db.cars.update({"_id":1}, {"$pop":{"mods":"headlights"}})
Now with that in mind. The easy way: in mongodb to add to array only if element does not exist you can use $addToSet. I love this operator because it will only add to array if the element does not exist. Here is how to use it:
db.cars.update({"_id":1}, {"$addToSet":{"mods":"headlights"}})
Now if headlights is in the array it will not be added, else it will be added to the end of array.
Okay that is the first part of the question. The second part which is initializing a document with an array. Okay there are two thoughts here: the first is you do not have to. using the addToSet you can create the array if it does not exist as (assuming _id 2 exist but without mods array):
db.cars.update({"_id":2}, {"$addToSet":{"mods":"bonnet"}})
This will create the array if document _id:2 exist. Assuming _id:3 does not exist you will have plug in a third attribute called upsert
db.cars.update({"_id":3}, {"$addToSet":{"mods":"headlights"}}, {upsert:true})
this will create a third document with array mods with headlights inside of it and _id:3. Note though no other attributes will be added only the _id and mods array
the second thought is when you insert a new document you insert it with empty mods array as mod:[]
I hope that helps
suppose your data_json ,dashboard_id and keyword contain following detail.
dashboard_id = ObjectId("5423200e6694ce357ad2a1ac")
keyword = "testingKeyword"
data_json =
{
"json_id":ObjectId("5423200e6694ce357ad2a1ac"),
"item":"EFG222",
"reorder":false,
}
if you execute below query
db.collection_name.update({"json_id":data_json["json_id"], "_dashbd_id_":dashboard_id},{{"$addToSet": {"array_field":keyword}},{ upsert=True})
than it will push keyword to array_field if document exist or it will insert new document with following detail as below.
{
"_id":ObjectId("5sdvsdv6sdv694ce357ad2a1ac"),
"json_id":ObjectId("5423200e6694ce357ad2a1ac"),
"dashboard_id": ObjectId("sddfb6694ce357ad2a1ac")
"item":"EFG222",
"reorder":false,
"array_field":
[
"testingKeyword"
]
}
I need to find all the documents in mongodb that have keywords that start with number 1-9, then add a '+' in front of the keyword, I can easily find the documents but cannot figure out how to update them.
I tried this one, but it doesn't work
db.placements.update({program_id:{$in:[113,107]},
keyword:{$regex:'^[0-9]', $options:'i'}},
{keyword:"+"+$keyword})
It cannot recognize $keyword, I also tried '.keyword', 'keyword', none of them works. Is there any way to reference the document itself like Java does, using 'this', so I can do something like
this.keyword: "+" + this.keyword
You'll have to use the $set operator in the update query to update a specific field. Also, you cannot concatenate string within an update query. One way to do this would be using cursor forEach() in the shell:
db.placements.find({program_id:{$in:[113,107]}, keyword:{$regex:'^[0-9]', $options:'i'}})
.forEach(function(doc){
db.placements.updateOne({_id:doc._id}, {$set:{"keyword":"+" + doc.keyword}})
})
No, you cannot reference a value on the document itself when querying like you can with SQL.
I would suggest querying the document, updating it on your web/app server and then updating the value back to mongodb.
You will also find that your update command above will wipe your entire document leaving only the keyword field. You should use the $set modifier to update a field or set of fields.
db.placements.update(
{
program_id:{$in:[113,107]},
keyword:{$regex:'^[0-9]', $options:'i'}
},
{ $set: {keyword: new_value}})
I have sample products table and would like to update multiple documents using _id field. Every time, I try this it only updates the first doc in the $in clause I mentioned , not updating all.
db.products.update({_id:{$in:[ObjectId("507d95d5719dbef170f15bff"),
ObjectId("507d95d5719dbef170f15c01"), ObjectId("507d95d5719dbef170f15c00")]}},
{$set:{'monthly_price':7865}}, {multi:true})
You can first try running find on the products table to make sure that all the object ids actually exist.
You can also try explain command
give this a try:
db.<collection>.update( { query }, {$set: {monthly_price:7865}}, false, true)
I think the object id's which you have given doesn't exist in the collection.
I tried using the following query and it worked for me.
db.test.update({_id:{$in:[ObjectId("57b33483e5b9ce24f4910855"),
ObjectId("57b33483e5b9ce24f4910856"),
ObjectId("57b33489e5b9ce24f4910857"),
ObjectId("57b33491e5b9ce24f4910858")
]
}
},
{$set{'isCurrentStatus':true}},
{multi:true}
)
I Use from Mongodb and have a collection like this:
{'name':'vahid','visited':[{id:1,'date':'1223123',noskhe:['a','d','h']]}
I want an update query to add {id:2,'date':'324324',noskhe:['d','n']} to visited array!
How I can get this query?
You need to use $push operator. It will append a new value to the array. Below is the example.
db.collection.update({"name":"vahid"},{$push:{ "visited": {id:2,'date':'324324',noskhe:['d','n']}}})