I have something like this for every user in mongoDB:
{
"id" : 1234,
"name" : "Mr. Someone",
"userdata" : {
"living" : {
"city" : "Somecity",
"address" : "Main Street 10.",
"zip" : "1023"
},
"interest" : "Cars"
}
I'm trying to find a way to count how many subscribers live in Somecity.
My best guess was the following:
db.users.count({userdata:{living:{city:"Somecity"}}}
But the result was 0.
How can I properly count "rows" by a given value in mongoDB?
I'm using mongoDB's documentation (for example: http://docs.mongodb.org/manual/reference/sql-comparison/) but could not resolve my problem yet.
I'm using mongoDB trough shell.
I think I have found the sollution to my problem:
db.users.count({"userdata.living.city":"Somecity"})
This "dotting" method allowed me to search for only one value in the array, while the method I tried first wanted to find an exact match.
Further reading: http://docs.mongodb.org/manual/reference/operator/query/elemMatch/
Quote:
Since the $elemMatch only specifies a single condition, the $elemMatch
expression is not necessary, and instead you can use the following
query:
db.survey.find( { "results.product": "xyz" } )
Related
There is a need for me to do bulk update of user details.
Let the object details have the following fields,
User First Name
User ID
User Last Name
User Email ID
User Country
An admin can upload the updated data of the users through a csv file. Values with mismatching data needs to be updated. The most probable request format for this bulk update request will be like:(Method 1)
"data" : {
"userArray" : [
{
"id" : 2343565432,
"f_name" : "David",
"email" : "david#testmail.com"
},
{
"id" : 2344354351,
"country" : "United States",
}
.
.
.
]
}
Method 2 : I would send the details in two arrays, one containing the list of similar filed values with respect to their user ids
"data" : {
"userArray" : [
{
"ids" : [23234323432, 4543543543, 45654543543],
"country" : ["United States", "Israel", "Mexico"]
},
{
"ids" : [2323432334543, 567676565],
"email" : ["groove#drivein.com", "zara#foobar.com"]
},
.
.
.
]
}
In method 1, i need to query the database for every user update, which will be more as the no of user edited is more. In contrast, if i use method 2, i query the database only once for each param(i add the array in the query and get those rows whose user id is present in the given array in a single query). And then i can update the each row with their respective details.
But overall in the internet, most of the update api had params in the format specified in method 1 which gives user good readability. But i need to know what will be advantage if i go with method 1 rather than method 2? (I save some query time in method 2 if the no of users count is large which can improve my performance)
I almost always see it being method 1 style.
Woth that said, I don't understand why your DB performance is based on the way the input data is structured. That's just the way information gets into your code.
You can have the client send the data as method 1 and then shim it to method 2 on the backend if that helps you structure the DB queries better
I want generate value using json schema. But json schema not support file type.So i add custom key word inheritType . Now i validate this schema it throw Exception.
So How to slove this problem. and How to add custom keyword in json schema
This My Json Schema
{
"type" : "object" ,
"properties" : {
"file" : {
"type" : "string" ,
"inheritType" : "File"
}
}
}
This is my java code throws Exception
{
"level" : "error",
"schema" : {
"loadingURI" : "#",
"pointer" : "/properties/file/inheritType" ,
"ignored" : ["inheritType"]
}
It sounds like you might want to add the keyword to those allowed, based on this github issue comment.
This is an implementation choice. The primary goal of these messages
is to, in fact, detect spelling mistakes (consider pattenrProperties
for instance).
As the report says, these warnings will be ignored; therefore you need
not worry about these.
Note that you have the option to either:
configure the log level so that those warnings do not appear in the
final log, or update the dictionary of keywords so that this keyword
is recognized.
I can't see how to do this in the javadocs though. Sorry.
I'm developing a chat app. In my app there are 4 nodes called User, Recent, Message, Group. I'm using Objective-C My message object looks like,
{
"createdAt" : 1.486618017521277E9,
"groupId" : "-KcWKeXXQ9tjYsYfCknx",
"objectId" : "-KcWKftK8GiMxxAnarL5",
"senderId" : "828949592937598976",
"senderImage" : "http://hairstyleonpoint.com/wp-content/uploads/2014/10/marcello-alvarez.png",
"senderName" : "John Doee",
"status" : "Seen",
"text" : "Hi all",
"type" : "text",
"updatedAt" : 1.486622011467733E9
}
When I'm updating a User, all message's senderName should be updated accordingly. Is there are way to do this via the code or Do I need to write a rule. I'm a newbie to the firebase. Please suggest me a way to do that. If It's possible to do with the rules, Please guide me on this.
It's not possible to do this via rules, so you have to manually iterate over all your data and update the senderName.
Anyways, I think you would probably be better off with saving {senderID: $someUserID} instead - like you would do in a relational database. The userID is static, so can change the user without having to update all the instances where you use it.
I am running local rediis for my application. I am using ServiceStack.Rediis client with C#.
I am storing items as an object type T with some key.
For example
Key "1234" : {
object {
name : "abcd",
value : "1"
}
}
I am storing something like 10000 objects of same type with key. I would like to apply pagination when i retrieve these objects and only show like 20 per page.
Is this possible? If yes, what should be a good way to resolve this?
Thanks,
Vivek
Use the SCAN command with a count of 20.
I'm trying to understand how ElasticSearch Query DSL works.
It would be a lot of help if anyone could give me an example how to perform a search like the following MySQL query:
SELECT * FROM products
WHERE shop_id = 1
AND MATCH(title, description) AGAINST ('test' IN BOOLEAN MODE)
Assuming that you indexed some documents containing at least the shop_id, title and description fields, something like the following example:
{
"shop_id" : "here goes your shop_id",
"title" : "here goes your title",
"description" : "here goes your description"
}
You can execute a multi match query against multiple fields, and give them a different weight (usually title is more important). You can also combine the query with a term filter on shop_id:
{
"query" : {
"multi_match" : {
"query" : "here goes your query",
"fields" : [ "title^2", "description" ]
},
"filter" : {
"term" : { "shop_id" : "here goes your shop id" }
}
}
You need to submit the query using the search API. Filters are used to reduce the set of documentsthe query is eecute against. Filters are faster since don't involve scoring and cached. In my example I applied a top level filter, which might be or not a good fit for you depending on what else you want to do next. If you want to make a facet, for instance, the filter would be ignored in the facet. Another way to add a filter, which would be taken into account while computing the facets as well, is the filtered query.