I recently encountered an issue, and I'd like to solve it. If anyone would give any suggestion I'll be grateful.
I have documents that represent "users" and each document has a subarray that is responsible to save some codes, they can be many for each user. The matter is, each user cannot have duplicate codes in its specific array, but at the same time, in this case, each document should be isolated, for example, being possible to have two or more identical codes but since they are from different documents(users).
In short, the subarray("codes") cannot have individually duplicated codes(code), but that shouldn't interfere with other documents
I could do that in the application part, but I think doing that guarantee directly on DB, it's safer.
Is it possible to create indexes for this specific situation?
Example of two documents representing their respective users:
{ // Document of user 1
"_id" : "1", //user 1 and its codes
"codes" : [
{
"code" : "1111",
"description" : "code 1",
},
{
"code" : "2222",
"description" : "code 2",
},
{
"code" : "3333",
"description" : "code 3",
}
]
},
{ // Document of user 2
"_id" : "2", //user 2 and its codes
"codes" : [
{
"code" : "1111",
"description" : "code 1",
},
{
"code" : "4444",
"description" : "code 2",
},
{
"code" : "2222",
"description" : "code 3",
}
]
}
Thank you!
Use https://docs.mongodb.com/manual/reference/operator/update/addToSet/ to maintain uniqueness of code subdocuments. You will need to ensure that you always specify code fields in the same order (e.g. code, description).
Related
I'm working on prototyping a note-taking application in Meteor; functional requirements include:
users have access to shared notes
notes contain distinct sections
each user needs to be able to add notations to notes/sections
notations can be preserved over time (e.g. add to existing notations without updating or deleting previously created notation)
notations should be private between users
Given the above, each document has a data key that contains the array of subdocuments - each section of the note. Something like this:
{
"_id" : ObjectId("someObjectID"),
"owner" : "Q5mpJZnAtFN5EMWT9",
"createdAt" : "2018-01-05T22:56:03.257Z",
"updatedAt" : "2018-01-06T12:07:03.123Z",
"parent" : null,
"title" : "Note Title",
"data" : [
{
"date" : "2018-01-05T22:56:03.257Z",
"title" : "Section 1 Title",
"text" : "Section content goes here..."
},
{
"date" : "2018-01-05T22:56:03.257Z",
"title" : "Section 2 Title",
"text" : "Section content goes here..."
}
]
}
For the main notes documents, the data array stores the sections as subdocuments; for user notations, the data array stores their personal notations as subdocuments. My thinking is to use the parent key to distinguish between shared notes and user notations:
parent : null for "top level", shared notes
something like parent : "yG8xrh6KiZXv7e8MD" to point back to the "top level" note or subdocument for user notations. (Hopefully this makes sense).
Two questions. First and foremost - is this a valid design?
If it IS a valid design, how do I then reference a specific subdocument? For example, in the above document, if a user wants to add a notation to Section 2 only? Can I add an _id to the subdocument and then use that value for the parent key in the notation document?
This not the complete solution, but just an example:
I would do it something like this. I'd modify your document a bit, adding notations field in every section:
{
"_id" : ObjectId("someObjectID"),
"owner" : "Q5mpJZnAtFN5EMWT9",
"createdAt" : "2018-01-05T22:56:03.257Z",
"updatedAt" : "2018-01-06T12:07:03.123Z",
"parent" : null,
"title" : "Note Title",
"data" : [
{
"date" : "2018-01-05T22:56:03.257Z",
"title" : "Section 1 Title",
"text" : "Section content goes here...",
"notations": [
{
_id: "some id",
version:1
userId: "fsajksffhj",
date: "2018-01-05T22:56:06",
note: "some note about this sectioon"
},
{
_id: "some id2",
version:1,
userId: "fsajksffhj",
date: "2018-01-05T22:56:06",
note: "some note about this sectioon"
},
{
_id: "some id1",
version:1,
userId: "fsajksffhj",
date: "2018-02-06T00:56:06",
note: "edited the first notation"
}
]
},
{
"date" : "2018-01-05T22:56:03.257Z",
"title" : "Section 2 Title",
"text" : "Section content goes here..."
}
]
}
notations should be private between users
This is harder part. I'd use Meteor Methods to do this. Another way could be to use MongoDB's aggregation functionality with match, unwind, re-match, group and create document again. You are using reactivity if using either of these.
Meteor.methods({
'notes.singleNote: function(noteId, notationsUserId) {
check(noteId, String);
check(notationsUserId);
let note = Notes.findOne(noteId);
// remove other users' notations
note.data = note.data.map(function(data) {
if (data.notations) {
data.notations = data.notations.filter(function(d) {
return d.userId === notationsUserId;
});
}
return data
});
});
return note;
}
});
I should start with: I'm knew to MongoDB, and document-style databases in general.
I have a collection that looks something like this:
{
"_id" : ObjectId("554a5e72b16f31ff0894310e"),
"title" : "ABC",
"admins" : [
"personA",
"personB",
],
"email_address" : "ABC#mysite.com"
}
{
"_id" : ObjectId("554a5e72b16f31ff0894310f"),
"title" : "Junk Site",
"admins" : [
"personA",
"personB"
],
"email_address" : "garbage#mysite.com"
}
{
"_id" : ObjectId("554a5e72b16f31ff08943110"),
"title" : "Company Three Site",
"admins" : [
"personC"
"personD",
],
"email_address" : "company2plus1#mysite.com"
}
What I need to do, is append the admins list from Company One, to Company Three such that Company Three now has four admins (A, B, C, D).
I tried the following, because it seemed pretty straight forward to me - get the data from the origin and append to destination directly:
db.runCommand({
findAndModify : 'sites',
query : {'title' : 'Company Three Site'},
update : { '$addToSet' :
{'admins' :
db.projects.find({'title' : 'ABC'}, {'_id' : 0, 'admins' : 1}
}
}
})
However, this does not work correctly.
I am still trying to figure out ways I could do this directly, but questions...
1) Is this even possible by using single command, or do I need to split this up?
2) Does my train of logical thought make sense, or should I be doing this some other/easier way that is more conventional for MongoDB style databases?
db.projects.find actually returns a cursor, which you definitely don't want to add to your set. Since you know ahead of time that you will be only finding one value, you can get the properties out of the cursor specifically by using .next().admin -- but remember that this will only work with the first value returned from .find. Otherwise, I think you will have to use a loop.
$addToSet will also add the array as a whole, so instead you have to append multiple values using $each
All together:
db.runCommand({
findAndModify: 'sites',
query: {'title': 'Company Three Site'},
update: {
$addToSet: {
"admins": {
$each: db.projects.find(
{"title": "ABC"},
{"_id": 0, "admins": 1}
).next().admins
}
}
}
})
This is not possible with an atomic update. However, a workaround is to query the source collection using the find() method and use the cursor's forEach() method to iterate over the results, get the array and update the destination collection using the $addToSet operator and the $each modifier.
Let's demonstrate this with the above sample documents inserted to a test collection:
db.test.insert([
{
"title" : "ABC",
"admins" : [
"personA",
"personB"
],
"email_address" : "ABC#mysite.com"
},
{
"title" : "Junk Site",
"admins" : [
"personA",
"personB"
],
"email_address" : "garbage#mysite.com"
},
{
"title" : "Company Three Site",
"admins" : [
"personC",
"personD"
],
"email_address" : "company2plus1#mysite.com"
}
])
The following operation will add the admins array elements from company "ABC" to the company "Company Three Site" admin array:
db.test.find({"title" : "ABC"}).forEach(function (doc){
var admins = doc.admins;
db.test.update(
{"title" : "Company Three Site"},
{
"$addToSet": {
"admins": { "$each": admins }
}
},
{ "multi": true }
);
});
Querying the collection for the document with company "Company Three Site" db.collection.find({"title" : "Company Three Site"});
will yield:
/* 0 */
{
"_id" : ObjectId("554a7dc35c5e0118072dd885"),
"title" : "Company Three Site",
"admins" : [
"personC",
"personD",
"personA",
"personB"
],
"email_address" : "company2plus1#mysite.com"
}
I am building a course system. Each course has multiple sections, each section has multiple steps. My datastructure is as follows:
{
"_id" : "Mtz4DMTwMMKWTWbzE",
"slug" : "how-to-be-awesome",
"title" : "How to be awesome",
"description" : "In 4 easy lessons.",
"createdAt" : ISODate("2014-08-25T13:33:24.675Z"),
"sections" : [
{
"title" : "Be cool",
"description" : "Title says it all really",
"steps" : [
{
"title" : "Wear sunglasses",
"description" : "Always works."
},
{
"title" : "Be funny",
"description" : "Make an occasional joke. But no lame ones."
}
]
}
]
}
This worked while adding steps;
Course._collection.update( { _id: course._id, sections: section }, {
"$push": {
"sections.$.steps": step
}
})
But I can't figure out how to update a step. I tried to give the steps an ID and do it like that, but it's not working, apparently because it's two arrays deep, and you can't have two positionals ($) in a query. I tried something like this:
Course._collection.update( { _id: course._id, 'sections.steps._id': step._id }, {
"$set": {
"sections.steps.$.title": "test updated title"
}
})
But this gave the following error:
can't append to array using string field name: steps
Is there a way to do this? Or is my schema design off?
Thanks!
I'm new to mongodb and javascript, and have been reading the manual, but I can't seem to put the pieces together to solve the following problem.. I was wondering if you can kindly help.
I have two collections "places" and "reviews".
One document in "places" collection is as follows:
{
"_id" : "004571a7-afe4-4124-996e-b6ec779db494",
"name" : "wakawaka place",
"address" : {
"address" : "12 ad avenue",
"city" : "New York",
},
"review" : [
{
"id" : "i32347",
"review_list" : [
"r123456",
"r123457"
],
}
]
}
The "review" array can be empty for some documents.
And in the "reviews" collection, every document in the collection represents a review:
{
"_id" : ObjectId("53c913689c8e91a5a9c4047f"),
"user_id" : "useridhere",
"review_id" : "r123456",
"attraction_id" : "i32347",
"content" : "review content here"
}
What I would like to achieve is, for each place that has reviews, get the content of each review from the "review" collection and store them together in another new collection.
I'd be grateful for any suggestions on how to go about this.
Thanks
I have the following items in my collection:
> db.test.find().pretty()
{ "_id" : ObjectId("532c471a90bc7707609a3d4f"), "name" : "Alice" }
{
"_id" : ObjectId("532c472490bc7707609a3d50"),
"name" : "Bob",
"partner_type1" : {
"status" : "rejected"
}
}
{
"_id" : ObjectId("532c473e90bc7707609a3d51"),
"name" : "Carol",
"partner_type2" : {
"status" : "accepted"
}
}
{
"_id" : ObjectId("532c475790bc7707609a3d52"),
"name" : "Dave",
"partner_type1" : {
"status" : "pending"
}
}
There are two partner types: partner_type1 and partner_type2. A user cannot be accepted partner in the both of types. But he can be a rejected partner in partner_type1 but accepted in the another, for example.
How can I build Mongo query that fetches the users that can become partners?
When your user can only be accepted in one partner-type, you should turn it around: Have a field accepted_as:"partner_type1" or accepted_as:"partner_type2". For people who aren't accepted yet, either have no such field or set it to null.
In both cases, your query to get any non-accepted will then be:
{
data.accepted_as: null
}
(null matches both non-existing fields as well as fields explicitly set to null)
For me the logical schema would be this:
"partner : {
"type": 1,
"status" : "rejected"
}
At least that keeps the paths consistent between documents.
So if you want to stay away from using mapReduce type methods to find out "which field" it is on, and otherwise use plain queries and the aggregation pipeline, then don't vary field paths on documents. If you alter the "data" then that is the most consistent form.