I was trying to change the strength based on the hero name in a document like this:
"_id" : ObjectId("52b0d27b5dee463864000001"),
"author" : "niko",
"permalink" : "super_heroes"
"hero" : [
{
"name" : "Batman",
"strength" : 1,
"magic" : [ ],
"times" : [ ]
},
I couldn't change it when initially trying:
var operator = { '$set' : { 'hero.strength' : strength } };
var query = { 'permalink': permalink , 'hero.name':name };
posts.update(query, operator, options, function(err, numModified) {...})
I got MongoError: can't append to array using string field name: strength.
But after seeing this post I added a dollar sign and it worked:
var operator = { '$set' : { 'hero.$.strength' : strength } };
What did that dollar sign in a JSON key do? I tried googling it, but I just came up with a million explanations of what jQuery is. Thank you.
This is not a JSON operator (there is no such things as JSON operator. You might think that JSON is a string).
In this context $ is a mongodb positional operator to perform update in a specific position.
Related
My Document structure is
"MainAccounts" : [
{
"orgs" : "5808ba773fe315441b9e0a9e",
"_id" : ObjectId("5808bc0c3fe315441b9e0b1a"),
"accounts" : [
"5808baf33fe315441b9e0aa7",
"5808baf33fe315441b9e0aa8",
"5808baf33fe315441b9e0aa9",
"5808baf33fe315441b9e0aa1"
]
},
{
"orgs" : "5808ba773fe315441b9e0a9f",
"_id" : ObjectId("5808bc0c3fe315441b9e0b1b"),
"accounts" : [
"5808baf33f35425852s255s7",
"5808baf3sd23s2d3d4w5s2s8",
"5808baf33sd211ds2d2sdsa9",
"5808baf33dssd2d21b9e0aa1"
]
}
],
I want to pull out a particular account say "5808baf33fe315441b9e0aa8" from this, i wrote the query like this.
{ $pull: { "MainAccounts.$.accounts": "5808baf33fe315441b9e0aa8"} }
It gives only error as "The positional operator did not find the match needed from the query. Unexpanded update: MainAccounts.$.accounts"
{ $pull: { "MainAccounts.0.accounts": "5808baf33fe315441b9e0aa8" } }
If i give like this it will remove that value only which gives the expected output.
i need output as
"MainAccounts" : [
{
"orgs" : "5808ba773fe315441b9e0a9e",
"_id" : ObjectId("5808bc0c3fe315441b9e0b1a"),
"accounts" : [
"5808baf33fe315441b9e0aa7",
"5808baf33fe315441b9e0aa9",
"5808baf33fe315441b9e0aa1"
]
},
{
"orgs" : "5808ba773fe315441b9e0a9f",
"_id" : ObjectId("5808bc0c3fe315441b9e0b1b"),
"accounts" : [
"5808baf33f35425852s255s7",
"5808baf3sd23s2d3d4w5s2s8",
"5808baf33sd211ds2d2sdsa9",
"5808baf33dssd2d21b9e0aa1"
]
}
],
here i am not able to delete value from second array i need to give
{ $pull: { "MainAccounts.1.accounts": "5808baf33fe315441b9e0aa8" } }
But i need to loop through, any help is appreciated.
You will get an error:
"Cannot apply $pull to a non-array value"
This should be :
db.collection.update({'MainAccounts.accounts': '5808baf33fe315441b9e0aa8'}, {$pull: {MainAccounts:{ accounts: '5808baf33fe315441b9e0aa8'}}})
Here is a reference to this:
mongodb Cannot apply $pull/$pullAll modifier to non-array, How to remove array element
db.collection.update({someId,{$pull : {"MainAccounts":{"accounts":"5808baf33fe315441b9e0aa8"}}}})
someId could be your _id.
Remember if you have to access the document inside the array you cant access it without . operator only.You have to use the index with it.The other way mongodb can access it is by the use of braces.
This will do what you want:
db.collection.update({'MainAccounts.accounts': '5808baf33fe315441b9e0aa8'}, {$pull: {'MainAccounts.$.accounts': '5808baf33fe315441b9e0aa8'}})
In mongodb. I have the following document/json with these (4) fields.
"ready_state" : {
"user" : "abcd#abc.com",
"state" : "green",
"audit_date" : ISODate("2016-04-03T14:27:11.494Z"),
"profile" : "tst"
},
How do I empty out this hash? Output expected would be:
"ready_state" : {
},
Can someone provide example on how to do so using pull and set?
You simply replace the value of ready_state with the new value. Using $set you can do something like this:
db.collection.update(query, { $set: { ready_state: {} });
I'm new to meteor/mongo/js as a stack and I'm getting lost in JSON arrays and referencing them. Based another SO answer ( and the docs) I think I am close...
A document in the Orders collection, the document has nested arrays.
Order -> orderLines -> lineItems:
Sample doc:
{
"_id" : "27tGpRtMWYqPpFkDN",
"orderLines" : [
{
"lineId" : 1,
"name" : "Cheese & Pickle",
"instructions" : "",
"lineItems" : [
{
"name" : "Cheddar Cheese",
"quantity" : 1
},
{
"name" : "Branston Pickle",
"quantity" : 1
},
{
"name" : "Focaccia Roll",
"quantity" : 1
}
]
}
]
}
What I'm trying to do from the meteor/mongo shell:
Add "instructions" of "foo" to orderLines where lineId = 1
Put a new item on lineItems array
This appears to hang...
meteor:PRIMARY> db.orders.update({_id:"27tGpRtMWYqPpFkDN","orderLines.lineId":"1", {$set: {"orderLines.$.instructions":"foo"}})
...
This doesn't like the identifier in the query
meteor:PRIMARY> db.orders.update({_id:"27tGpRtMWYqPpFkDN", "orderLines.lineId":"1"}, {$push:{"orderLines.$.lineItems":" { "name" : "butter", "quantity" : 1}"}});
2015-10-27T16:09:54.489+0100 SyntaxError: Unexpected identifier
Thanks all for your comments... but I found out some answers, posted for reference
Item 1 - using $set on a value within an array
This was failing due to two typos, one missing closing } at the end of the query, second was quoting the value "1" for itemId in the query.
This works:
db.orders.update({_id:"27tGpRtMWYqPpFkDN", orderLines.lineId":1},
{$set: {"orderLines.$.instructions":"foo"}})
I also realised that when I said "It appears to hang" it is the cli waiting for a valid statement, so hints at a missing } or )!
Item 2 - using $push to add data to an array - 2 levels nested
This was failing due to quoting around the array data
db.orders.update({_id:"27tGpRtMWYqPpFkDN", "orderLines.lineId":1 },
{$push:{"orderLines.$.lineItems": { "name" : "butter", "quantity" : 1} }})
Nested Arrays: can use $ positional operator
What I want to do next is use $set on an item in the second level array, and this would require using the $ positional operator twice:
db.orders.update({"orderLines.lineId":1, lineItems.name:"Cheddar Cheese"},
{$set: {"orderLines.$.lineItems.$.quantity": 2}})
This throws an error:
Too many positional (i.e. '$') elements found in path
There is an open MongoDB enhancement request for this but it's been open since 2010
$push adds a new element to an array. You're merely trying to set the value of a particular key in an array element.
Try:
db.orders.update({ _id: "27tGpRtMWYqPpFkDN", "orderLines.lineId": 1},
{ $set: { "orderlines.$.instructions": "foo" }})
docs
how can I return a specific value for a specific document in MongoDB? For example, I have a schema that looks like:
{
"_id" : "XfCZSje7GjynvMZu7",
"createdAt" : ISODate("2015-03-23T14:52:44.084Z"),
"services" : {
"password" : {
"bcrypt" : "$2a$10$tcb01VbDMVhH03mbRdKYL.79FPj/fFMP62BDpcvpoTfF3LPgjHJoq"
},
"resume" : {
"loginTokens" : [ ]
}
},
"emails" : {
"address" : "abc123#gmu.edu",
"verified" : true
},
"profile" : {
"companyName" : "comp1",
"flagged" : true,
"phoneNum" : "7778883333"
}}
I want to return and store the value for profile.flagged specifically for the document with _id : XfCZSje7GjynvMZu7. So far I have tried:
db.users.find({_id:'myfi3E4YTf9z6tdgS'},{admin:1})
and
db.users.find({_id: 'myfi3E4YTf9z6tdgS'}, {profile:admin});
I want the query to return true or false depending on the assigned value.
Can someone help? Thanks!
MongoDB queries always return document objects, not single values. So one way to do this is with shell code like:
var flagged =
db.users.findOne({_id: 'myfi3E4YTf9z6tdgS'}, {'profile.flagged': 1}).profile.flagged;
Note the use of findOne instead of find so that you're working with just a single doc instead of the cursor that you get with find.
The correct answer here is the method .distinct() (link here)
Use it like this:
db.users.find({_id:'myfi3E4YTf9z6tdgS'},{admin:1}).distinct('admin')
The result will be: 1 or 0
Because of a weird bug in my code, I have a collection with field names which are stricly numbers (ex: 34344,54675,34356).
Now I try to move these fields values to another fields (ex: name,email,etc) but when I run the update command:
db.collection.find({"id_field" : 1996}).forEach(function (elem) {db.collection.update({_id: elem._id},{$set: {name: elem.36536}});});
All I get is an error:
SyntaxError: Unexpected number
How should I handle it? I already tried with elem[36536] instead elem.36536 but without success.
if I got your problem right, this code might help you:
db.collection.find({"id_field" : 1996}).forEach(function (elem)
{
var value = elem['36536'];
db.collection.update({_id: elem._id},{$set: {name: value}});
});
If your document is like this
{
"_id" : 1,
"elem" : {
"123" : "barno",
"456" : "foo#gmail.com"
}
}
you can $rename the key document.
db.d.update({"_id" : 1},{$rename:{'elem.123':'elem.name','elem.456':'elem.email'}})
Result:
{
"_id" : 1,
"elem" : {
"name" : "barno",
"email" : "foo#gmail.com"
}
}