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How to query sub document (list type) in Cosmos Db

I have a collection in Azure CosmosDB, and each document looks like this:
{
"id": "random",
"TeacherName": "Ben",
"Students": [
{
"Name": "John",
"Telephone": ""
},
{
"Name": "Mary",
"Telephone": ""
}
],
}
TeacherName is string, Students is a list of student
I need to do: Given a user name (user1), query and return all the documents, either teacher name is "user1" or there is a student with name "user1".
I tried a few options, but cannot do it.
The closest solution I found so far is to use .SelectMany(), but I found .SelectMany will do a join and will duplicate the return results.
This is my query:
client.CreateDocumentQuery().SelectMany((x) => x.Students.Where(s=>s.Name == "user1" || x.TeacherName == "user1")
If only the above sample document in the collection, and when I searched user name "Ben", 2 records will be returned ((number of result) * (number of students)). I have to remove the duplicate at client side and pagination is kind of broken.
Is it possible to issue a single query to achieve what I need?

client.CreateDocumentQuery().SelectMany((x) => x.Students.Where(s=>s.Name == "user1" || x.TeacherName == "user1")
Actually the SelectMany method in your code is similar to the sql as below:
SELECT c.id from c
join x in c.Students
where c.TeacherName ='Ben' or x.Name = 'Ben'
Output
[
{
"id": "1"
},
{
"id": "1"
}
]
If there's a join, there's going to be duplicate data. As far as I know, automatic removal of duplicate data is not supported (like Distinct Keywords in traditional database) by Azure Cosmos DB yet.
It seems that there is no way to remove the repeat data in the query SQL level.
If you don't want to handle with your query result set in the loop locally, I strongly suggest you using a stored procedure to handle with result data in Azure Cosmos DB to release the pressure on your local server.
Or , you could complete the query directly in the Stored Procedure if your data is not too large.Please refer to the js code as below:
// SAMPLE STORED PROCEDURE
function sample(idsArrayString,courses) {
var collection = getContext().getCollection();
var isAccepted = collection.queryDocuments(
collection.getSelfLink(),
'SELECT * FROM root r',
function (err, feed, options) {
if (err) throw err;
if (!feed || !feed.length) getContext().getResponse().setBody('no docs found');
else {
var returnResult = [];
for(var i = 0;i<feed.length;i++){
var doc = feed[i];
if(doc.TeacherName == 'Ben'){
returnResult.push(feed[i]);
break;
}
var std = doc.Students;
for (var s in std) {
if(s.Name == 'Ben'){
returnResult.push(feed[i]);
break;
}
}
}
getContext().getResponse().setBody(returnResult);
}
});
if (!isAccepted) throw new Error('The query was not accepted by the server.');
}
Update Answer:
I checked the Azure Cosmos DB pricing details. Then it doesn't show that stored procedure is more expensive than a single query. Actually, the cost depends on Rus and RuS depends on the complexity of the query and the amount of concurrency, etc.
You could refer to the RUs document. Also , you could know the RUs charge by the http request header :x-ms-request-charge. Please see this useful trace:
How to caculate the Azure Cosmos DB RU used in server side scripting.
Hope it helps you.

DocumentDB filter an array by an array

I have a document that looks essentially like this:
{
"Name": "John Smith",
"Value": "SomethingIneed",
"Tags: ["Tag1" ,"Tag2", "Tag3"]
}
My goal is to write a query where I find all documents in my database whose Tag property contains all of the tags in a filter.
For example, in the case above, my query might be ["Tag1", "Tag3"]. I want all documents whose tags collection contains Tag1 AND Tag3.
I have done the following:
tried an All Contains type linq query
var tags = new List<string>() {"Test", "TestAccount"};
var req =
Client.CreateDocumentQuery<Contact>(UriFactory.CreateDocumentCollectionUri("db", "collection"))
.Where(x => x.Tags.All(y => tags.Contains(y)))
.ToList();
Created a user defined function (I couldn't get this to work at all)
var tagString = "'Test', 'TestAccount'";
var req =
Client.CreateDocumentQuery<Contact>(UriFactory.CreateDocumentCollectionUri("db", "collection"),
$"Select c.Name, c.Email, c.id from c WHERE udf.containsAll([${tagString}] , c.Tags)").ToList();
with containsAll defined as:
function arrayContainsAnotherArray(needle, haystack){
for(var i = 0; i < needle.length; i++){
if(haystack.indexOf(needle[i]) === -1)
return false;
}
return true;
}
Use System.Linq.Dynamic to create a predicate from a string
var query = new StringBuilder("ItemType = \"MyType\"");
if (search.CollectionValues.Any())
{
foreach (var searchCollectionValue in search.CollectionValues)
{
query.Append($" and Collection.Contains(\"{searchCollectionValue}\")");
}
}
3 actually worked for me, but the query was very expensive (more than 2000 RUs on a collection of 10K documents) and I am getting throttled like crazy. My result set for the first iteration of my application must be able to support 10K results in the result set. How can I best query for a large number of results with an array of filters?
Thanks.

The UDF could be made to work but it would be a full table scan and so not recommended unless combined with other highly-selective criteria.
I believe the most performant (index-using) approach would be to split it into a series of AND statements. You could do this programmatically building up your query string (being careful to fully escape and user-provided data for security reasons). So, the resulting query would look like:
SELECT *
FROM c
WHERE
ARRAY_CONTAINS(c.Tags, "Tag1") AND
ARRAY_CONTAINS(c.Tags, "Tag3")

MongoDB C# driver, query by an array element using regex

I am using MongoDB C# driver version 2.2. My collection contains "Parent" objects. Each parent object has an array of children objects. Each child has name value:
"parent": {
"children":[
{ "name": "Bob", "age": 10},
{ "name": "Alice", "age": 7},
{ "name": "Tobias", "age": 11}
]
}
I need to translate the following code into C# statements / LINQ syntax:
db.getCollection('Parents').find({'parent.children': { $elemMatch: { 'name': { $regex: '.*ob.*', $options: 'im' } }}})
I have found there are methods like
var builder = Builders<BsonDocument>.Filter;
builder.Regex("parent.children.name", new BsonRegularExpression(".*ob.*")); //does not work with array
and
builder.AnyEq("parent.children.name", "ob"); //without regex
But I cannot understand how to combine them. Please advise.
UPDATE:
I am using the following for now, please correct me if you know a reason why it should not work correctly:
builder.AnyEq("parent.children.name", new BsonRegularExpression(".*ob.*"))

I am using the following for now:
builder.AnyEq("parent.children.name", new BsonRegularExpression(".*ob.*"))

Can't test C# on this machine. Let me know if this doesn't work:
var filter = Builders<People>.Filter.ElemMatch(x => x.Parent.Children, x => Regex.IsMatch(x.Name, "regex"));
var res = await collection.Find(filter).ToListAsync();
Here's a trick you might like btw:
// Take your inputted `find` query string:
string bsonQuery = "{'parent.children': { $elemMatch: { 'name': { $regex: '.*ob.*', $options: 'im' } }}}";
// Use it as the filter!
var filter = MongoDB.Bson.Serialization.BsonSerializer.Deserialize<BsonDocument>(bsonQuery);
// Results:
var result = col.FindSync (filter).ToList();

I've tested your current expression (builder.AnyEq("parent.children.name", new BsonRegularExpression(".*ob.*")) on a database at home and I don't believe it behaves in the way you intend.
Although the c# documentation doesn't explicitly state this, mongoDB supports the Regex filter on an array field. I have tested the below expression in C# and have correct results for the Regex despite the field being an array.
builder.Regex(MONGO_FIELD_NAME, new BsonRegularExpression("SOME REGEX"));
In addition, I've tested Regex on the toy example in the [online mongo webshell for query arrays] (https://docs.mongodb.com/manual/tutorial/query-arrays/). Querying for db.inventory.find({tags : {$regex : "^bl"}} will return results with "blank" or "blue" despite the "tag" field being an array.

Mongodb Array Update

I have following mongodb json.I would like to update price of product_id:2 from 4 to 5 in the document with document _id:id1
Can someone guide me how to do that in mongodb or using c#
{
"_id": "id1",
"products": [
{
"product_id": "pr1",
"price":1,
"qty":5
},
{
"product_id": "pr2",
"price":4,
"qty":10
},
{
"product_id": "pr3",
"price":8,
"qty":9
}
]
}

Download the C# mongodb driver from mondodb site.
var collection = DataBase.GetCollection<MyProducts>("products");
var query = Query<MyProduct>.Where(p => (m.productID == "pr2"));
var product = collection.FindOne(query);
product.Price = 5;
collection.Save(product);

Either use the .update function in mongo db or pull the object out using linq something like:
var query = (from c in Collection.AsQueryable<T>() where c.Id == Id select c).First<T>();
adjusting the above variables accordingly.
Then changing whatever that object is then saving it using Collection.Save(obj) this will re write the whole object. Look here: http://docs.mongodb.org/manual/reference/method/db.collection.save/ and http://docs.mongodb.org/manual/tutorial/modify-documents/

How do I order a sql datasource of uniqueidentifiers in Linq by an array of uniqueindentifiers

I have a string list(A) of individualProfileId's (GUID) that can be in any order(used for displaying personal profiles in a specific order based on user input) which is stored as a string due to it being part of the cms functionality.
I also have an asp c# Repeater that uses a LinqDataSource to query against the individual table. This repeater needs to use the ordered list(A) to display the results in the order specified.
Which is what i am having problems with. Does anyone have any ideas?
list(A)
'CD44D9F9-DE88-4BBD-B7A2-41F7A9904DAC',
'7FF2D867-DE88-4549-B5C1-D3C321F8DB9B',
'3FC3DE3F-7ADE-44F1-B17D-23E037130907'
Datasource example
IndividualProfileId Name JobTitle EmailAddress IsEmployee
3FC3DE3F-7ADE-44F1-B17D-23E037130907 Joe Blo Director dsd#ad.com 1
CD44D9F9-DE88-4BBD-B7A2-41F7A9904DAC Maxy Dosh The Boss 1
98AB3AFD-4D4E-4BAF-91CE-A778EB29D959 some one a job 322#wewd.ocm 1
7FF2D867-DE88-4549-B5C1-D3C321F8DB9B Max Walsh CEO 1

There is a very simple (single-line) way of doing this, given that you get the employee results from the database first (so resultSetFromDatabase is just example data, you should have some LINQ query here that gets your results).
var a = new[] { "GUID1", "GUID2", "GUID3"};
var resultSetFromDatabase = new[]
{
new { IndividualProfileId = "GUID3", Name = "Joe Blo" },
new { IndividualProfileId = "GUID1", Name = "Maxy Dosh" },
new { IndividualProfileId = "GUID4", Name = "some one" },
new { IndividualProfileId = "GUID2", Name = "Max Walsh" }
};
var sortedResults = a.Join(res, s => s, e => e.IndividualProfileId, (s, e) => e);
It's impossible to have the datasource get the results directly in the right order, unless you're willing to write some dedicated SQL stored procedure. The problem is that you'd have to tell the database the contents of a. Using LINQ this can only be done via Contains. And that doesn't guarantee any order in the result set.

Turn the list(A), which you stated is a string, into an actual list. For example, you could use listAsString.Split(",") and then remove the 's from each element. I’ll assume the finished list is called list.
Query the database to retrieve the rows that you need, for example:
var data = db.Table.Where(row => list.Contains(row.IndividualProfileId));
From the data returned, create a dictionary keyed by the IndividualProfileId, for example:
var dic = data.ToDictionary(e => e.IndividualProfileId);
Iterate through the list and retrieve the dictionary entry for each item:
var results = list.Select(item => dic[item]).ToList();
Now results will have the records in the same order that the IDs were in list.