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Dynamically Query a Mongo Collection in c#

I'm new to C# mongo,earlier worked on Node and Mongo.
i have a collection called tasks.Below is a sample record.
{
"_id" : ObjectId("6193bfba23855443a127466a"),
"taskIdentifier" : LUUID("00000000-0000-0000-0000-000000000000"),
"title" : "PR Liquidators",
"company" : "iuytreugdfh",
"purpose" : "test purpose",
"column" : "Search",
"assignTo" : "Shiva",
"assignToId" : ObjectId("61933b47a79ac615648a7855"),
"assignToImage" : null,
"notes" : "ggh#William james ",
"done" : 0,
"taskID" : "00029",
"status" : "Pending",
"states" : [
"Alabama - AL",
"Alaska - AK"
],
"active" : true,
"updatedAtUtc" : ISODate("2021-11-18T12:26:37.616Z"),
"updatedBy" : ""
}
in my c# webapi Project i always get a array called filterCriteria from api request of below form:
filterCriteria=[
{key:"purpose",value:"test purpose",type:"eq"},
{key:"active",value:true,type:"eq"}
]
Now I want to query the mongo collection tasks using the given filterCriteria.
tried something using LINQ statements but no use --hardcoding works but dynamically not working.
How can I achieve this???

maybe you are looking for Builders:
public enum FilterType{
eq=1,//equal
gt=2//greater than
}
//************
var builder = Builders<FilterCritertiaModel>.Filter;
var query = builder.Empty;
foreach(var filterCriteriaItem in filterCriteria){
switch (filterCriteriaItem.type) {
case eq:
query &= builder.Eq(filterCriteriaItem.Key, filterCriteriaItem.Value);
case gt:
query &=builder.Gt(filterCriteriaItem.Key, filterCriteriaItem.Value);
//all cases....
}

Find if an element in array has value equal to parent element value

Let's say we have a collection of documents like this one:
{
"_id" : ObjectId("591c54faf1c1f419a830b9cf"),
"fingerprint" : "3121733676",
"screewidth" : "1920",
"carts" : [
{
"cartid" : 391796,
"status" : "New",
"cart_created" : ISODate("2017-05-17T13:50:37.388Z"),
"closed" : false,
"items" : [
{
"brandid" : "PIR",
"cai" : "2259700"
}
],
"updatedon" : ISODate("2017-05-17T13:51:24.252Z")
},
{
"cartid" : 422907,
"status" : "New",
"cart_created" : ISODate("2017-10-23T08:57:06.846Z"),
"closed" : false,
"items" : [
{
"brandid" : "PIR",
"cai" : "IrHlNdGtLfBoTlKsJaRySnM195U"
}
],
"updatedon" : ISODate("2017-10-23T09:46:08.579Z")
}
],
"createdon" : ISODate("2016-11-08T10:29:55.120Z"),
"updatedon" : ISODate("2017-10-23T09:46:29.486Z")
}
How do you extract only the documents where no item in the array $.carts have $.carts.closed set to true and $.carts.updatedon greater than $.updatedon minus 3 days ?
I know how to do find all the documents where no item in the array satisfy the condition $and: [closed: {$eq: true}, {updatedon: {$gt : new ISODate("2017-10-20T20:15:31Z")}}]
But how can you reference the parent element $.updatedon for the comparison?
In plain mongodb shell query language it would aleady be of help.
But I am actually accessing it using c# driver, so my query filter is like this:
FilterDefinition<_visitorData> filter;
filter = Builders<_visitorData>.Filter
.Gte(f => f.updatedon, DateTime.Now.AddDays(-15));
filter = filter & (
Builders<_visitorData>.Filter
.Exists(f => f.carts, false)
| !Builders<_visitorData>.Filter.ElemMatch(f =>
f.carts, c => c.closed && c.updatedon > DateTime.Now.AddDays(-15)
)
);
How can I replace DateTime.Now.AddDays(-15) with a reference to the document root element updatedon?

You can project the difference of carts.updatedon and updatedon and then filter out the results from this aggregation pipeline.
coll.aggregate([{'$unwind':'$carts'},
{'$match':{'closed':{'$ne':true}}},
{'$project':{'carts.cartid':1,'carts.status':1,'carts.cart_created':1,'carts.closed':1,'carts.items':1,'carts.updatedon':1,'updatedon':1,'diff':{'$subtract':['$carts.updatedon','$createdon']}}},
{'$match': {'diff': {'$gte': 1000 * 60 * 60 * 24 * days}}}])
days = 3 will filter out results more than 3 days difference documents.
I have just given the example of how you can use $subtract to find date difference and filter documents based on that.

well I was in a similar situation few days back.
I tackled it by using Jobject of Newtonsoft.Json.
Create a function to return bool which actually process each document take it as input.
Jobject jOb=Jobject.parse(<Your document string>);
JArray jAr=JArray.Parse(jOb["carts"]);
If(jOb["updateon"]=<Your Business Validation>)
{
foreach(var item in jAr)
if(item["closed"]==<Your validation>){ return true}
}
return false;
I hope this helps :)
If you handling with any null values in those properties then please use Tryparse and out variable.

Aggregation with MongoDB C# Driver [duplicate]

Is there a query for calculating how many distinct values a field contains in DB.
f.e I have a field for country and there are 8 types of country values (spain, england, france, etc...)
If someone adds more documents with a new country I would like the query to return 9.
Is there easier way then group and count?

MongoDB has a distinct command which returns an array of distinct values for a field; you can check the length of the array for a count.
There is a shell db.collection.distinct() helper as well:
> db.countries.distinct('country');
[ "Spain", "England", "France", "Australia" ]
> db.countries.distinct('country').length
4
As noted in the MongoDB documentation:
Results must not be larger than the maximum BSON size (16MB). If your results exceed the maximum BSON size, use the aggregation pipeline to retrieve distinct values using the $group operator, as described in Retrieve Distinct Values with the Aggregation Pipeline.

Here is example of using aggregation API. To complicate the case we're grouping by case-insensitive words from array property of the document.
db.articles.aggregate([
{
$match: {
keywords: { $not: {$size: 0} }
}
},
{ $unwind: "$keywords" },
{
$group: {
_id: {$toLower: '$keywords'},
count: { $sum: 1 }
}
},
{
$match: {
count: { $gte: 2 }
}
},
{ $sort : { count : -1} },
{ $limit : 100 }
]);
that give result such as
{ "_id" : "inflammation", "count" : 765 }
{ "_id" : "obesity", "count" : 641 }
{ "_id" : "epidemiology", "count" : 617 }
{ "_id" : "cancer", "count" : 604 }
{ "_id" : "breast cancer", "count" : 596 }
{ "_id" : "apoptosis", "count" : 570 }
{ "_id" : "children", "count" : 487 }
{ "_id" : "depression", "count" : 474 }
{ "_id" : "hiv", "count" : 468 }
{ "_id" : "prognosis", "count" : 428 }

With MongoDb 3.4.4 and newer, you can leverage the use of $arrayToObject operator and a $replaceRoot pipeline to get the counts.
For example, suppose you have a collection of users with different roles and you would like to calculate the distinct counts of the roles. You would need to run the following aggregate pipeline:
db.users.aggregate([
{ "$group": {
"_id": { "$toLower": "$role" },
"count": { "$sum": 1 }
} },
{ "$group": {
"_id": null,
"counts": {
"$push": { "k": "$_id", "v": "$count" }
}
} },
{ "$replaceRoot": {
"newRoot": { "$arrayToObject": "$counts" }
} }
])
Example Output
{
"user" : 67,
"superuser" : 5,
"admin" : 4,
"moderator" : 12
}

I wanted a more concise answer and I came up with the following using the documentation at aggregates and group
db.countries.aggregate([{"$group": {"_id": "$country", "count":{"$sum": 1}}}])

You can leverage on Mongo Shell Extensions. It's a single .js import that you can append to your $HOME/.mongorc.js, or programmatically, if you're coding in Node.js/io.js too.
Sample
For each distinct value of field counts the occurrences in documents optionally filtered by query
> db.users.distinctAndCount('name', {name: /^a/i})
{
"Abagail": 1,
"Abbey": 3,
"Abbie": 1,
...
}
The field parameter could be an array of fields
> db.users.distinctAndCount(['name','job'], {name: /^a/i})
{
"Austin,Educator" : 1,
"Aurelia,Educator" : 1,
"Augustine,Carpenter" : 1,
...
}

To find distinct in field_1 in collection but we want some WHERE condition too than we can do like following :
db.your_collection_name.distinct('field_1', {WHERE condition here and it should return a document})
So, find number distinct names from a collection where age > 25 will be like :
db.your_collection_name.distinct('names', {'age': {"$gt": 25}})
Hope it helps!

I use this query:
var collection = "countries"; var field = "country";
db[collection].distinct(field).forEach(function(value){print(field + ", " + value + ": " + db[collection].count({[field]: value}))})
Output:
countries, England: 3536
countries, France: 238
countries, Australia: 1044
countries, Spain: 16
This query first distinct all the values, and then count for each one of them the number of occurrences.

If you're on MongoDB 3.4+, you can use $count in an aggregation pipeline:
db.users.aggregate([
{ $group: { _id: '$country' } },
{ $count: 'countOfUniqueCountries' }
]);

MongoDB C# List the latest of all entries on a sub document

Is it possible to list all the restaurants and their latest grade, if grades is a an array within a restaurant?
{
"_id" : ObjectId("56bf7957b5e096fd06b755b2"),
"grades" : [
{
"date" : ISODate("2014-11-15T00:00:00.000Z"),
"grade" : "Z",
"score" : 38
},
{
"date" : ISODate("2014-05-02T00:00:00.000Z"),
"grade" : "A",
"score" : 10
},
{
"date" : ISODate("2013-03-02T00:00:00.000Z"),
"grade" : "A",
"score" : 7
},
{
"date" : ISODate("2012-02-10T00:00:00.000Z"),
"grade" : "A",
"score" : 13
}
],
"name" : "Brunos On The Boulevard",
}
I would want to get:
{
"_id" : ObjectId("56bf7957b5e096fd06b755b2"),
"grades" : [
{
"date" : ISODate("2014-11-15T00:00:00.000Z"),
"grade" : "Z",
"score" : 38
}
],
"name" : "Brunos On The Boulevard",
}
Explanation
The answer below uses the unwind operator. There's a really simple explanation of it on this answer, should anyone be confused by it as I was.

An option could be doing an aggregate with two operations, an Unwind which deconstructs your array field from the input documents to output a document for each element, and later a sort operation by date in descending order. This way you can get the result you are expected selecting the first element from the aggregate result:
var result = collection.Aggregate()
.Unwind(e => e["grades"])
.SortByDescending(e=>e["grades.date"])
.FirstOrDefault();

MongoDb 3.0 C# updating subdocument of subdocument

Below is an example of my document. I am trying to update the CostReports part based on the id of the CostReportingPeriods element.
{
"_id" : "240106",
"CostReportingPeriods" : [
{
"FyBgnDt" : ISODate("2000-01-01T05:00:00.000Z"),
"FyEndDt" : ISODate("2000-12-31T05:00:00.000Z"),
"_id" : "240106-20000101-20001231",
"CostReports" : []
},
{
"FyBgnDt" : ISODate("2001-01-01T05:00:00.000Z"),
"FyEndDt" : ISODate("2001-12-31T05:00:00.000Z"),
"_id" : "240106-20010101-20011231",
"CostReports" : []
},
{
"FyBgnDt" : ISODate("2002-01-01T05:00:00.000Z"),
"FyEndDt" : ISODate("2002-12-31T05:00:00.000Z"),
"_id" : "240106-20020101-20021231",
"CostReports" : []
},
{
"FyBgnDt" : ISODate("2003-01-01T05:00:00.000Z"),
"FyEndDt" : ISODate("2003-12-31T05:00:00.000Z"),
"_id" : "240106-20030101-20031231",
"CostReports" : []
}
]
I am using the following code to try and update that element but am getting an error that says cannot use the element (CostReportingPeriods of CostReportingPeriods.CostReports) to traverse the element. If I add CostReportingPeriods.0.CostReports it will add it to the first element of the array, regardless of the filter.
var builder = Builders<MongoModels.Provider>.Filter;
var filter = builder.Eq("_id",costReport.PRVDR_NUM) & builder.Eq("CostReportingPeriods._id", costReport.UNIQUE_ID);
var update = Builders<MongoModels.Provider>.Update.AddToSet("CostReportingPeriods.CostReports", Mapper.Map<CostReport, MongoModels.CostReport>(costReport, opt =>
{
opt.AfterMap((src, dest) => dest.Worksheets = CreateWorksheets(dest.RptRecNum).ToList());
}));
How do I get it to update the element I want it to update based on the id of the subdocument?

After trying a bunch of different things, by channging my update filter from "CostReportingPeriods.CostReports" to "CostReportingPeriods.$.CostReports" it works flawlessly.