I am new to cloud-ant, In my current assignment i want to search all distinct records based on fields x:
I have documents which have domain as attribute. I want all unique domains which are present in my db.Below is the example,
documentNo1-{"domain":"gmail.com"}
documentNo2-{"domain":"ymail.com"}
documentNo3-{"domain":"gmail.com"}
expected result is API should return only unique domain name, like below
[gmail.com,ymail.com]
I am not getting operators in cloud-ant which can achieve this, only solution i have is to retrieve it and create our own unique domain list.
Looking for any good approach/solution for above scenario.
You can use Cloudant Search to create a faceted index.
See https://console.bluemix.net/docs/services/Cloudant/api/search.html#faceting
This would allow you to essentially group documents by domain, creating the unique list you need.
There is a good video tutorial showing this technique:
https://www.youtube.com/watch?v=9er3XI150VM
Related
I know how to check if an array contains a given string (as explained for example here). My requirement however is different: I have a document with an array updatedByHistoryArray written at server side that contains the history of the ids of all users who updated such a document, for example [id1, id2, ..., idn].
I would like to allow a delete operation for this document only if the latter has been updated exclusively by the user who wants to delete it.
So, for example, if a user with id24 wants to delete a document, the updatedByHistoryArray of this document has to be [id24, id24, ..., id24].
Is it possible to implement this requirement in the security rules of Firestore?
It sounds possible. Try using hasOnly() to see if the list field contains only a single user ID.
resource.data.updatedByHistoryArray.hasOnly([request.auth.uid])
I have few questions about collection group:
Is there way to execute request for collection group in Firestore simulator?
Can I add additional parameter for collection group rules for example the following rule is used for collection group
match /{prefix=**}/access/{email} {
allow read: if isSignedIn();
}
before access collection i have one more collection with user id, is is possible to add it as parameter to do some validations?
No, there currently is no way to simulate a collection group query in the Firestore console. (Actually there is no querying at all except individual document gets.)
There is no way, using security rules, to know any of the other path elements that come before access in the case you're showing. The prefix wildcard actually will not even contain any data at the time of execution.
The chat app schema that I have is something like below.
1. conversations {participants[user_1, user_2], convsersation_id}
2. messages {sender: user_1, sonversation_id, timestamps}
I want to map this relationship using existing _id:ObjectId which is already indexed.
But if I want to get all conversation of user_1 I have to first search in which conversation that user is involed and get that conversation's _id and again search for the messages in messages using that conversation _id.
So my questions are -
Does length of indexed field (here _id) matters while searching?
Should I create another shorter indexed fields?.
Also if there is any better alternative schema please suggest.
I would suggest you to maintain the data as sub documents instead of array. The advantage you have is you can build another index (only) on conversation_id field, which you want to query to know the user's involvement
When you maintain it as array, you cannot index the converstaion_id field separately, instead you will have to build a multi key index, which indexes all the elements of the array (sender and timestamps fields) which you are never going to use for querying and it also increases the index size
Answering you questions:
Does length of indexed field (here _id) matters while searching? - Not really
Should I create another shorter indexed fields? - Create sub-document and index converstaion_id
Also if there is any better alternative schema please suggest. - Maintain the array fields as sub-documents
QUERYING MONGODB: RETREIVE SHOPS BY NAME AND BY LOCATION WITH ONE SINGLE QUERY
Hi folks!
I'm building a "search shops" application using MEAN Stack.
I store shops documents in MongoDB "location" collection like this:
{
_id: .....
name: ...//shop name
location : //...GEOJson
}
UI provides to the users one single input for shops searching. Basically, I would perform one single query to retrieve in the same results array:
All shops near the user (eventually limit to x)
All shops named "like" the input value
On logical side, I think this is a "$or like" query
Based on this answer
Using full text search with geospatial index on Mongodb
probably assign two special indexes (2dsphere and full text) to the collection is not the right manner to achieve this, anyway I think this is a different case just because I really don't want to apply sequential filter to results, "simply" want to retreive data with 2 distinct criteria.
If I should set indexes on my collection, of course the approach is to perform two distinct queries with two distinct mehtods ($near for locations and $text for name), and then merge the results with some server side logic to remove duplicate documents and sort them in some useful way for user experience, but I'm still wondering if exists a method to achieve this result with one single query.
So, the question is: is it possible or this kind of approach is out of MongoDB purpose?
Hope this is clear and hope that someone can teach something today!
Thanks
I searched everywhere for this but I can't find anything on that matter. If you don't predefine fields in MongoDB, couldn't a user with Insert permission then Insert a document with every kind of field he wants? Via Collection.insert? If I am thinking correctly here, is there a way to restrict this?
You can restrict inserting any kind of fields in these two ways:
Use collection.allow/deny(http://docs.meteor.com/#/full/allow) - the insert callback has a doc parameter, which contains the exact document that user wants to insert - you can check the content of it and deny the insertion if you spot fields that are not allowed.
Use SimpleSchema (https://github.com/aldeed/meteor-simple-schema) and Collection2 (https://github.com/aldeed/meteor-collection2) packages to define the schema and attach it to your collection - it will prevent the insertion if a document has additional/missing fields (or fields of not expected type).
This is my personal preference. Because fieldNames param in
Collections.update(userId, doc, fieldNames) only gives top-level fields in doc. So if you are having nested fields it is very hard to track.
So I don't use collection allow/deny rules. Without allow deny rules Collections.insert/Collections.update does nothing on client. Instead I am using Meteor methods to update/delete documents to collections, so I can decide which exact fields should update/insert.