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MongoDB.NET Driver query for $lte and $gte throwing error: An object representing an expression must have exactly one field

FilterDefinition<DM.Content> filterDefinition = Builders<DM.Content>.Filter.Empty;
filterDefinition &= Builders<DM.Content>.Filter.Eq(x => x.IsDeleted, false);
if (contentTypeId > 0)
{
if (contentTypeId == 4)// Photo Video recipes
{
filterDefinition &= Builders<DM.Content>.Filter.In(x => x.ContentTypeId, new List<int>() { 1, 2 });// Video Photo recipes Recipes
}
else
{
filterDefinition &= Builders<DM.Content>.Filter.Eq(x => x.ContentTypeId, contentTypeId);
}
}
// rating
if (!string.IsNullOrEmpty(rating))
{
//filterDefinition &= Builders<DM.Content>.Filter.Gte(x => x.ContentAverageRating, rating);
filterDefinition &= new BsonDocument("$expr", new BsonDocument("$gte",
new BsonArray {
new BsonDocument("$toDouble", "$ContentAverageRating"),
Convert.ToDouble(rating)
}));
}
// cookTime
if (!string.IsNullOrEmpty(cookTime))
{
filterDefinition &= new BsonDocument("$expr", new BsonDocument("$lte",
new BsonArray {
new BsonDocument("$toDouble", "$ContentTime"),
Convert.ToDouble(cookTime)
}));
}
SortDefinition<DM.Content> sortDefinition = Builders<DM.Content>.Sort.Descending(x => x.UpdatedDate);
var results = await contentDocument.AggregateByPage(filterDefinition, sortDefinition, pageIndex, pageSize);
return new DM.CustomModels.ContentSearchResult() { ContentItems = results.data.ToList(), TotalPages = results.totalPages };
public static async Task<(int totalPages, IReadOnlyList<TDocument> data)> AggregateByPage<TDocument>(
this IMongoCollection<TDocument> collection,
FilterDefinition<TDocument> filterDefinition,
SortDefinition<TDocument> sortDefinition,
int page,
int pageSize)
{
var countFacet = AggregateFacet.Create("count",
PipelineDefinition<TDocument, AggregateCountResult>.Create(new[]
{
PipelineStageDefinitionBuilder.Count<TDocument>()
}));
var dataFacet = AggregateFacet.Create("data",
PipelineDefinition<TDocument, TDocument>.Create(new[]
{
PipelineStageDefinitionBuilder.Sort(sortDefinition),
PipelineStageDefinitionBuilder.Skip<TDocument>((page - 1) * pageSize),
PipelineStageDefinitionBuilder.Limit<TDocument>(pageSize),
}));
var aggregation = await collection.Aggregate()
.Match(filterDefinition)
.Facet(countFacet, dataFacet)
.ToListAsync();
var count = aggregation.First()
.Facets.First(x => x.Name == "count")
.Output<AggregateCountResult>()?
.FirstOrDefault()?
.Count ?? 0;
var totalPages = (int)Math.Ceiling((double)count / pageSize);
var data = aggregation.First()
.Facets.First(x => x.Name == "data")
.Output<TDocument>();
return (totalPages, data);
}
I am trying to execute the above query to check ContentAverageRating, ContentTime with certain conditions. But throwing an exception:
Command aggregate failed: An object representing an expression must have exactly one field: { $gte: [ { $toDouble: "$ContentAverageRating" }, 3.0 ], $lte: [ { $toDouble: "$ContentTime" }, 15.0 ] }.
Can anyone let me know what is wrong with the above query?

Issue & Concern
From what I suspect, MongoDB .Net driver had placed both $gte and $lte under the same $expr value, which make the whole BsonDocument failed.
Expected generated Bson Document
{
$and: [
{ $expr: { $gte: [/* Match Condition */] } },
{ $expr: { $lte: [/* Match Condition */] } }
]
}
Actual generated Bson Doccument
{
$and: [
{ $expr: { $gte: [/* Match Condition */], $lte: [/* Match Condition */] } }
]
}
Solution
After some trial and error, I suggest that remove the BsonDocument with $expr from both $lte and $gte. Then you create another FilterDefinition, rootFilterDefinitionto place $expr at top level, then append the filterDefinition as below:
filterDefinition &=
new BsonDocument("$gte",
new BsonArray {
new BsonDocument("$toDouble", "$ContentAverageRating"),
Convert.ToDouble(rating)
}
);
filterDefinition &=
new BsonDocument("$lte",
new BsonArray {
new BsonDocument("$toDecimal", "$ContentTime"),
Decimal.Parse(cookTime)
}
);
FilterDefinition<BsonDocument> rootFilterDefinition = new BsonDocument("$expr",
filterDefinition.ToBsonDocument());
var results = await contentDocument.AggregateByPage(rootFilterDefinition , sortDefinition, pageIndex, pageSize);
Equivalent to this MongoDB query
db.collection.aggregate([
{
$match: {
$expr: {
$and: [
{
$gte: [
{
$toDouble: "$ContentAverageRating"
},
3.0
]
},
{
$lte: [
{
$toDouble: "$ContentTime"
},
15.0
]
}
]
}
}
}
])
Sample Mongo Playground

$[<identifier>] operator syntax in C# MongoDB Driver for nested array update in a Document

I need to update point Description field highlighted inside the nested Document using C# Mongo DB driver. I can do this update successfully using following query.
Document Structure
{
"ControllerID": "testcon",
"CCNID": "testccn",
"TableGroup": 1,
"Tables": [
{
"ID": 0,
"TableGroupID": 1,
"Blocks": [
{
"ID": 0,
"TableID": 0,
"TableGroupID": 1,
"ControllerID": "testcon",
"Points": [
{
"BlockID": 0,
"TableGroupID": 1,
"ControllerID": "testcon",
"TableID": 0,
"PointDefinitionID": 23,
"Name": "Test Point",
"Description": "Hgfhdhfhey You" <----------- This field needs to be updated
},
{
"BlockID": 0,
"TableGroupID": 1,
"ControllerID": "testcon",
"TableID": 0,
"PointDefinitionID": 24,
"Name": "Test Point",
"Description": "Hgfhdhfhey You"
}
]
}
]
}
]
}
I can successfully update the point Description using this query.
db.ControllerPointCollection.updateOne({
"_id": "HRDC_testccn_0_34_1"
},
{
$set: {
"Tables.$[t].Blocks.$[b].Points.$[p].Description": "Hey You"
}
},
{
arrayFilters: [
{
"t.ID": 0
},
{
"b.ID": 0
},
{
"p.PointDefinitionID": 23
}
]
})
I tried using this filter and update object for the above operation
var pointFilter = Builders<Point>.Filter.Eq(p => p.PointDefinitionID, point.PointDefinitionID);
var blockFilter = Builders<Block>.Filter.Eq(b => b.ID, point.BlockID) & Builders<Block>.Filter.ElemMatch(b => b.Points, pointFilter);
var tableFilter = Builders<Table>.Filter.Eq(t => t.ID, point.TableID) & Builders<Table>.Filter.ElemMatch(t => t.Blocks, blockFilter);
var filter = Builders<ControllerPointDataDoc>.Filter.Eq(c => c.ID, point.ControllerID) & Builders<ControllerPointDataDoc>.Filter.ElemMatch(c => c.Tables, tableFilter);
var updater = Builders<ControllerPointDataDoc>.Update.Set(c => c.Tables[-1].Blocks[-1].Points[-1].Description, "Hey You");
operationResult.Data = await ControllerPointDataCollection.UpdateOneAsync(filter, updater);
but I am getting the following error.
A write operation resulted in an error.\r\n Too many positional (i.e. '$') elements found in path 'Tables.$.Blocks.$.Points'

MongoDB in C# - what is the right way to perform multiple filtering

I have a MongoDB collection of Persons (person_Id, person_name, person_age)
I want to return an object that contains:
number_of_all_persons
number_of_all_persons with age < 20
number_of_all_persons with age >= 20 && age <= 40
number_of_all_persons with age > 40
What is the right way to do it in Mongo using C#?
Should I run 4 different Filters to achieve result?

You can use Aggregation.
const lowerRange = { $lt: ["$person_age", 20] };
const middleRange = { $and: [{ $gte: ["$person_age", 20]}, { $lte: ["$person_age", 40] }] };
// const upperRange = { $gt: ["$person_age", 40] };
db.range.aggregate([
{
$project: {
ageRange: {
$cond: {
if: lowerRange,
then: "lowerRange",
else: {
$cond: {
if: middleRange,
then: "middleRange",
else: "upperRange"
}
}
}
}
}
},
{
$group: {
_id: "$ageRange",
count: { $sum: 1 }
}
}
]);
Here the total count is not included as you can calculate it from the count of the ranges. If you have more that 3 ranges, a better idea would be to pass an array of $cond statements to the project stage, as nesting multiple if/else statements starts to get harder to maintain. Here is a sample:
$project: {
"ageRange": {
$concat: [
{ $cond: [ { $lt: ["$person_age", 20] }, "0-19", ""] },
{ $cond: [ { $and: [ { $gte: ["$person_age", 20] }, { $lte: ["$person_age", 40] } ] }, "20-40", ""] },
{ $cond: [ { $gt: ["$person_age", 40] }, "41+", ""] }
]
}
}

You have several possible solutions here.
Filter with mongo
Filter with Linq
Looks like you are having an "and" filter here. You can do your filtering as described here: Link to filtering
Or, depending on how large your persons collection is, you could do query for all objects and filter with linq:
var collection.FindAll().Where(x => (x.age < 20) && (x.age >= 20 && x.age <= 40) ...)
The above is not syntax correct but I hope you get the idea behind it.
My approach would be creating a filter builder and and adding it to the find method call.
var highExamScoreFilter = Builders<BsonDocument>.Filter.ElemMatch<BsonValue>(
"scores", new BsonDocument { { "type", "exam" },
{ "score", new BsonDocument { { "$gte", 95 } } }
});
var highExamScores = collection.Find(highExamScoreFilter).ToList();
Hope this helps somehow.

Linq query to filter multi level classes

I have my departments data coming from the database. I want to filter this data based on certain criteria.
[
{
"Id":10,
"Name":"Name 10",
"Teachers":[
{
"TeacherId":100,
"TeacherName":null,
"DepartmentId":100,
"Students":[
{
"StudentId":1001,
"StudentName":null,
"TeacherId":10,
"DepartmentId":100
}
]
},
{
"TeacherId":101,
"TeacherName":null,
"DepartmentId":100,
"Students":[
{
"StudentId":1001,
"StudentName":null,
"TeacherId":10,
"DepartmentId":100
}
]
}
]
},
{
"Id":100,
"Name":"Name 10",
"Teachers":[
{
"TeacherId":0,
"TeacherName":null,
"DepartmentId":100,
"Students":[
{
"StudentId":5000,
"StudentName":null,
"TeacherId":50,
"DepartmentId":100
}
]
}
]
},
{
"Id":50,
"Name":"Name 10",
"Teachers":[
{
"TeacherId":0,
"TeacherName":null,
"DepartmentId":100,
"Students":[
{
"StudentId":2000,
"StudentName":null,
"TeacherId":50,
"DepartmentId":100
}
]
}
]
}
]
Now I have to filter the departments based on some values as shown below
var departmenIds = new List<int>() { 10, 20, 30 };
var teachers = new List<int>() { 100, 200, 300 };
var students = new List<int>() { 1000, 2000, 3000 };
I am looking for a query that will return the data in a following fashion
If all department ids exists in the json it will return entire data. If a department with a particular teacher is in the list then only return that teacher and the department. like wise for the student.
I tried this to test if it atleast work at the second level but I am getting all the teachers
var list = allDeplrtments.Where(d => d.Teachers.Any(t => teachers.Contains(t.TeacherId))).ToList();

var list = allDepartments
.Where(d => departmentIds.Contains(d.Id))
.Select(d => new Department() {
Id = d.Id,
Name = d.Name,
Teachers = (d.Teachers.Any(t => teacherIds.Contains(t.TeacherId))
? d.Teachers.Where(t => teacherIds.Contains(t.TeacherId))
: d.Teachers)
.Select(t => new Teacher() {
TeacherId = t.TeacherId,
TeacherName = t.TeacherName,
DepartmentId = d.Id,
Students = t.Students.Any(s => studentIds.Contains(s.StudentId))
? t.Students.Where(s => studentIds.Contains(s.StudentId))
: t.Students
})
})
Would something like this work for you?

Can't do multiple groups in MongoDB C# Driver

I am trying to show a statistics count, per month, per manufacturer from a MongoDB collection using Linq.I would like to see my data as:
[{
Manufacturer: '',
Statistics: [{
Month: '',
Counts: 0
}]
}]
So I am trying the following linq query:
var result = _statisticsRepository
.All()
.GroupBy(g => g.ManufacturerId)
.Select(s => new
{
Manufacturer = s.Key,
Statistics = s
.GroupBy(a => a.Values["DATA_MONTH"])
.Select(a => new
{
Month = a.Key,
Counts = a.Sum(d => d.Count)
})
});
When I try this code I get this error:
NotSupportedException: The method GroupBy is not supported in the expression tree: {document}.GroupBy(a => a.Values.get_Item("DATA_MONTH")).
Am I doing this the wrong way or is this a limitation I have in the C# driver? Or is there another way to do this?

You could use the aggregation framework instead LINQ to get the data that you need:
var group1 = new BsonDocument
{
{ "_id", new BsonDocument{{"ManufacturerId", "$ManufacturerId"},{"DATA_MONTH", "$DATA_MONTH"} }},
{ "Count", new BsonDocument
{
{
"$sum", $Count }
} }
};
var group2 = new BsonDocument
{
{ "_id", "$_id.ManufacturerId" },
{ "Statistics ", new BsonDocument { { "$addToSet",new BsonDocument{{"Month", "$_id.DATA_MONTH"},{"Count","$Count"} } } }},
};
var result = database.GetCollection<BsonDocument>("Manufacturers").Aggregate()
.Group(group1)
.Group(group2)
.ToList();