Delete collection in mongodb - database

I have the following json file in mongodb:
{
"_id" : ObjectId("59de156faf75d539b47e8db3"),
"user" : "user1",
"item" : {
"32a1fsd32asfd65asdf65" : {
...
},
"32a1fsd32asfd555" : {
}, ...
}
}
I want to perform a query and delete one of the two items. As a matter of fact, my database contains several users. Therefore, in order to retrieve the specific one from the mongodb i am performing the following:
How can I retrieve also a specific item and delete all its fields (for example 32a1fsd32asfd65asdf65)?

Based on the example document provided in your document it looks like you want to remove an attribute of the subdocument item.
You can use the $unset update operator:
db.getCollection('colName').update(
// find a specific document
{user: 'user1'},
// unset the attribute named "sfd65asdf65"
{$unset: {'item.sfd65asdf65': 1}}
)
Given the document provided in your question, the above command will cause that document to be updated to:
{
"_id" : ObjectId("59de156faf75d539b47e8db3"),
"user" : "user1",
"item" : {
"sd32asfd555" : {
...
}
}
}
If you want to remove the item attribute entirely then you would run:
db.getCollection('colName').update(
// find a specific document
{user: 'user1'},
// unset the attribute named "32a1fsd32asfd65asdf65"
{$unset: {'item': 1}}
)
And if you want to empty the item attribute (i.e. remove all of its attributes but retain the item attribute) then you would run this command:
db.getCollection('colName').update(
// find a specific document
{user: 'user1'},
// overwrite the "item" attribute with an empty sub document
{$set: {'item': {}}}
)
You can find more examples in the docs.

Say we have some users:
> db.test.insert( { _id: 1, user: "bob", field1: 1, field2 :{ field3 : 2 } } )
WriteResult({ "nInserted" : 1 })
> db.test.insert( { _id: 2, user: "fred", field1: 1, field2 :{ field3 : 2 } } )
WriteResult({ "nInserted" : 1 })
We can then use replaceOne to find the user and also then just replace the whole document, thus removing all the fields from that document:
> db.test.replaceOne( { user: "bob"}, { user: "bob" } )
{ "acknowledged" : true, "matchedCount" : 1, "modifiedCount" : 1 }
Then our new documents will look like:
> db.test.find()
{ "_id" : 1, "user" : "bob" }
{ "_id" : 2, "user" : "fred", "field1" : 1, "field2" : { "field3" : 2 } }

Related

Rename a sub-document field within an Array of an Document

I am trying to rename the particular child field inside an array of an collection in MONGODB
{
"_id" : Id("248NSAJKH258"),
"isGoogled" : true,
"toCrawled" : true,
"result" : [
{
"resultsId" : 1,
"title" : "Text Data to be writen",
"googleRanking" : 1,
"isrelated" : false
},
{
"resultId" : 2,
"title" : "Text Data",
"googleRanking" : 2,
"isrelated" : true
}]
**I need to rename "isrelated" to "related" ** from the collection document
Using mongo Version 4.0
I Tried :
db.collection_name.update({}, { $rename: { 'result.isrelated': 'result.related'} } )
But it didn't worked in my case
As mentioned in official documentation $rename not working for arrays.
Please check link below:
https://docs.mongodb.com/manual/reference/operator/update/rename/
But you can do something like this
let newResult = [];
db.aa1.find({}).forEach(doc => {
for (let i in doc.result) {
newResult.push({
"resultsId" : doc.result[i]['resultsId'],
"title" : doc.result[i]['title'],
"googleRanking" : doc.result[i]['googleRanking'],
"related" : doc.result[i]['isrelated'],
})
}
db.aa1.updateOne({_id: doc._id}, {$set: {result: newResult}});
newResult = []
})

Copy a field from one collection to another in mongodb with foreign key as mixed type

Although i have found a similar question on stackOverFlow MongoDB copy a field to another collection with a foreign key
I want to copy a field name from userdetails collection to user collection where userId in userDetails equals _id in user.
user collection
{
"_id" : ObjectId("5b97743bbff66e0be66283cc"),
"username" : "mmi_superadmin",
"accId" : "acc1"
}
{
"_id" : "c21d580ea3ca5c7a1664bd5feb57f0c8",
"username" : "client",
"accId" : "acc1"
}
userDetail collection
{
"_id" : ObjectId("5b97743bbff66e0be66283cd"),
"userId" : "5b97743bbff66e0be66283cc",
"name" : "mmi_superadmin"
}
{
"_id" : "5bab8a60ef86bf90f1795c44",
"userId" : "c21d580ea3ca5c7a1664bd5feb57f0c8",
"name" : "RAHUL KUMAR TIWARI"
}
Here is my query :
db.userDetails.find().forEach(
function(x) {
db.user.update( {_id :x.userId}, {$set: {name:x.name}});
}
);
This query is partially working. It only updates user documents where _id is of type string. User document with _id as ObjectId are not getting updated.
Please check your documents _id's (because in your example some _id's is not valid documents _id's. for example c21d580ea3ca5c7a1664bd5feb57f0c8 not a mongo _id) and use this query:
let usersIds = [];
db.user.find({"_id": {$type: 7}}).forEach(doc => {
usersIds.push(doc._id + '')
db.userDetail.find({
userId: {
$in: usersIds
}
}).forEach(doc => {
db.user.update(
{
"_id": ObjectId(doc.userId)
},
{
$set: {
"name": doc.name
}
},
{
multi: false,
upsert: false
}
)
})
})
if you have any question feel free to ask

MongoDB Update array in a document

I try to update arrays of multiple document with this query :
db.BusinessRequest.update({"DealTypes": { $exists: true }, "DealTypes.DisplayName": "Minority trade sale" }, {$set:{"DealTypes.$.DisplayName":"Minority"}}, false,true );
but when there is a match, it only updates the first row of my array whereas the displayName does not match with the first.
I use IntelliShell of MongoChef software.
My document looks like this :
{
"_id" : BinData(4, "IKC6QJRGSIywmKTKKRfTHA=="),
"_t" : "InvestorBusinessRequest",
"Title" : "Business Request 000000002",
"DealTypes" : [
{
"_id" : "60284B76-1F45-49F3-87B5-5278FF49A304",
"DisplayName" : "Majority",
"Order" : "001"
},
{
"_id" : "64A52AFE-2FF5-426D-BEA7-8DAE2B0E59A6",
"DisplayName" : "Majority trade sale",
"Order" : "002"
},
{
"_id" : "C07AE70D-4F62-470D-BF65-06AF93CCEBFA",
"DisplayName" : "Minority trade sale",
"Order" : "003"
},
{
"_id" : "F5C4390A-CA7D-4AC8-873E-2DC43D7F4158",
"DisplayName" : "Equity fund raising",
"Order" : "004"
}
]
}
How can I achieve this please ? Thanks in advance
EDIT :
This line works :
db.BusinessRequest.update({"DealTypes": { $exists: true }, "DealTypes": { $elemMatch: {"DisplayName": "Majority trade sale"}}}, {$set:{"DealTypes.$.DisplayName":"Majority"}}, false,true );
Please try this :
db.BusinessRequest.find().forEach( function(doc) {
do {
db.BusinessRequest.update({{"DealTypes": { $exists: true }, "DealTypes.DisplayName": "Minority trade sale" },
{$set:{"DealTypes.$.DisplayName":"Minority"}});
} while (db.getPrevError().n != 0);
})
or
You cannot modify multiple array elements in a single update operation. Thus, you'll have to repeat the update in order to migrate documents which need multiple array elements to be modified. You can do this by iterating through each document in the collection, repeatedly applying an update with $elemMatch until the document has all of its relevant comments replaced.
db.BusinessRequest.update({"DealTypes": { $exists: true }, "DealTypes": { $elemMatch: {"DisplayName": "Majority trade sale"}}}, {$set:{"DealTypes.$.DisplayName":"Majority"}}, false,true );
If you need efficiency in the search then I suggest you to normalise schema where each row is kept in separate document.
Please execute the following script in your mongo shell :
db.BusinessRequest.find({"DealTypes":{$exists:true}}).forEach(function(item)
{
for(i=0;i < item.DealTypes.length;i++)
{
if(item.DealTypes[i].DisplayName === 'Minority trade sale'){
item.DealTypes[i].DisplayName = 'Minority';
}
}
db.BusinessRequest.save(item);
});
Last two arguments in your update have a problem.
This is the form of update() method in mongodb
db.collection.update(
<query>,
<update>,
{
upsert: <boolean>,
multi: <boolean>,
writeConcern: <document>
}
)
I believe your update should be like this;
db.BusinessRequest.update
( {"DealTypes": { $exists: true }, "DealTypes.DisplayName": "Minority trade sale" }
, {$set:{"DealTypes.$.DisplayName":"Minority"}}
{ upsert : false, multi : true });

mongo add to nested array if entry does not contain two fields that match

I have a mongo document that contains an array called history:
{
"_id" : ObjectId("575fe85bfe98c1fba0a6e535"),
"email" : "email#address",
"__v" : 0,
"history" : [
{
"name" : "Test123",
"organisation" : "Rat",
"field" : 4,
"another": 3
}
]
}
I want to add fields to each history object or update fields IF the name AND organisation match, however if they don't, I want to add a new object to the array with the queried name and organisation and add/update the other fields to the object when necessary.
So:
This query, finds one that matches:
db.users.find({
email:"email#address",
$and: [
{ "history.name": "Test123", "history.organisation": "Rat"}
]
})
However, I'm struggling to get the update/upsert to work IF that combination of history.name and history.organisation dont exist in the array.
What I think I need to do is a :
"If this history name does not equal 'Test123' AND the history organisation does not equal 'Rat' then add an object to the array with those fields and any other field provided in the update query."
I tried this:
db.users.update({
email:"email#address",
$and: [
{ "history.name": "Test123", "history.organisation": "Rat"}
]
}, {
history: { name: "Test123"},
history: { organisation: "Rat"}
}, {upsert:true})
But that gave me E11000 duplicate key error index: db.users.$email_1 dup key: { : null }
Any help greatly appreciated.
Thanks community!
Not possible with a single atomic update I'm afraid, you would have to do a couple of update operations that satisfy both conditions.
Break down the update logic into two distinct update operations, the first one would require using the positional $ operator to identify the element in the history array you want and the $set to update the existing fields. This operation follows the logic update fields IF the name AND organisation match
Now, you'd want to use the findAndModify() method for this operation since it can return the updated document. By default, the returned document does not include the modifications made on the update.
So, armed with this arsenal, you can then probe your second logic in the next operation i.e. update IF that combination of "history.name" and "history.organisation" don't exist in the array. With this second
update operation, you'd need to then use the $push operator to add the elements.
The following example demonstrates the above concept. It initially assumes you have the query part and the document to be updated as separate objects.
Take for instance when we have documents that match the existing history array, it will just do a single update operation, but if the documents do not match, then the findAndModify() method will return null, use this logic in your second update operation to push the document to the array:
var doc = {
"name": "Test123",
"organisation": "Rat"
}, // document to update. Note: the doc here matches the existing array
query = { "email": "email#address" }; // query document
query["history.name"] = doc.name; // create the update query
query["history.organisation"] = doc.organisation;
var update = db.users.findAndModify({
"query": query,
"update": {
"$set": {
"history.$.name": doc.name,
"history.$.organisation": doc.organisation
}
}
}); // return the document modified, if there's no matched document update = null
if (!update) {
db.users.update(
{ "email": query.email },
{ "$push": { "history": doc } }
);
}
After this operation for documents that match, querying the collection will yield the same
db.users.find({ "email": "email#address" });
Output:
{
"_id" : ObjectId("575fe85bfe98c1fba0a6e535"),
"email" : "email#address",
"__v" : 0,
"history" : [
{
"name" : "Test123",
"organisation" : "Rat",
"field" : 4,
"another" : 3
}
]
}
Now consider documents that won't match:
var doc = {
"name": "foo",
"organisation": "bar"
}, // document to update. Note: the doc here does not matches the current array
query = { "email": "email#address" }; // query document
query["history.name"] = doc.name; // create the update query
query["history.organisation"] = doc.organisation;
var update = db.users.findAndModify({
"query": query,
"update": {
"$set": {
"history.$.name": doc.name,
"history.$.organisation": doc.organisation
}
}
}); // return the document modified, if there's no matched document update = null
if (!update) {
db.users.update(
{ "email": query.email },
{ "$push": { "history": doc } }
);
}
Querying this collection for this document
db.users.find({ "email": "email#address" });
would yield
Output:
{
"_id" : ObjectId("575fe85bfe98c1fba0a6e535"),
"email" : "email#address",
"__v" : 0,
"history" : [
{
"name" : "Test123",
"organisation" : "Rat",
"field" : 4,
"another" : 3
},
{
"name" : "foo",
"organisation" : "bar"
}
]
}

MongoDB search using $in array not working

I'm using MongoDB shell version: 2.4.8, and would simply like to know why a nested array search doesn't work quite as expected.
Assume we have 2 document collections, (a) Users:
{
"_id" : ObjectId("u1"),
"username" : "user1",
"org_ids" : [
ObjectId("o1"),
ObjectId("o2")
]
}
{
"_id" : ObjectId("u2"),
"username" : "user2",
"org_ids" : [
ObjectId("o1")
]
}
and (b) Organisations:
{
"_id" : ObjectId("o1"),
"name" : "Org 1"
}
{
"_id" : "ObjectId("o2"),
"name" : "Org 2"
}
Collections have indexes defined for
Users._id, Users.org_id, Organisations._id
I would like to find all Organisations a specific user is a member of.
I've tried this:
> myUser = db.Users.find( { _id: ObjectId("u1") })
> db.Organisations.find( { _id : { $in : [myUser.org_ids] }})
yet it yields nothing as a result. I've also tried this:
> myUser = db.Users.find( { _id: ObjectId("u1") })
> db.Organisations.find( { _id : { $in : myUser.org_ids }})
but it outputs the error:
error: { "$err" : "invalid query", "code" : 12580 }
(which basically says you need to pass $in an array) ... but that's what I thought I was doing originally ? baffled.
Any ideas what I'm doing wrong?
db.collection.find() returns a cursor - according to documentation. Then myUser.org_ids is undefined, but $in field must be an array. Let's see the solution!
_id is unique in a collection. So you can do findOne:
myUser = db.Users.findOne( { _id: ObjectId("u1") })
db.Organisations.find( { _id : { $in : myUser.org_ids }})
If you are searching for a non-unique field you can use toArray:
myUsers = db.Users.find( { username: /^user/ }).toArray()
Then myUsers will be an array of objects matching to the query.

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