I'm using the mongo-csharp-driver to query my Mongo entities.
I have the following objects which are stored in the Mongo:
public class Table
{
public int Id { get; private set; }
public string Description{ get; private set; }
public List<Player> Players { get; private set; }
public Table()
{
}
}
public class Player
{
public int Id { get; private set; }
public string Username{ get; private set; }
public Player()
{
}
}
When I'm trying to query the "Table" object by id or description, I get the appropriate results, but when I try to query by the list of player, I get null:
// Works ok
var tab1 = mongo.GetCollection<Table>().Where(g => g.Description == "Test");
// Always return null, although should return the same result
var tab2 = mongo.GetCollection<Table>().Where(g => g.Players.Count > 90).FirstOrDefault();
What am I missing here?
Thanks,
Nir.
The issue is that Count property is translated into the $size query operator.
From the linked Advanced Queries page you can see that:
"You cannot use $size to find a range of sizes (for example: arrays
with more than 1 element)."
Related
With the SDK of Azure.Data.Tables I’m trying to write a query that groups the data and fetches the highest value from each group. Is there a way to achieve this?
Currently I’m fetching all the data and executing the following LINQ query:
public class SomeClass
{
public string CompanyName { get; set; }
public long SomeValue { get; set; }
public string ProperyAttribute1 { get; set; }
public string ProperyAttribute2 { get; set; }
public long ProperyAttribute3 { get; set; }
}
List<SomeClass> someList = FetchingDataFromCosmosDbTableStorage(); //fetching all the data
var result = someList.GroupBy(x => x.CompanyName)
.Select(y => y.OrderByDescending(i => i.SomeValue).First())
.ToList();
Instead of filtering all the data in my application I would prefer to write a query to get the same result from CosmosDb Table.
I need to filter a list by the DamageCodeName field in the DamageCode class.
public partial class DamageCategory
{
public string DamageCategoryId { get; set; }
public string CategoryName { get; set; }
}
public partial class DamageGroup
{
public string DamageGroupId { get; set; }
public string DamageCategoryId { get; set; }
public string GroupName { get; set; }
}
public partial class DamageCode
{
public string DamageCodeId { get; set; }
public string DamageGroupId { get; set; }
public string DamageCodeName { get; set; }
}
I pull the records using EF CORE 5 into a list:
private List<DamageCategory> _DamageCodeList { get; set; } = new();
_DamageCodeList = _contextDB.DamageCategories
.Include(i => i.DamageGroups)
.ThenInclude(d => d.DamageCodes).AsSingleQuery().ToListAsync();
Now I need to filter this list by the DamageCode.DamageCodeName property.
private string _SearchText { get; set; } = "Bubble";
private List<DamageCategory> _CategoryList { get; set; } = new();
_CategoryList = _DamageCodeList.Where(g => g.DamageGroups.SelectMany(c => c.DamageCodes
.Where(w => w.DamageCodeName.ToLower().Contains(_SearchText.ToLower()))).Any()).ToList();
The code above only filters for the DamageCategory. It brings back all the records for the DamageGroup and all the records for the DamageCodes.
I need the linq query result to produce a list like the one below (Filtered by "Bubble") and bring back only the DamageCategory, DamageGroup, and DamageCodes filtered by DamageCode.DamageCodeName.Contains("Bubble"):
Here is the SQL that produces the result above that I need:
SELECT
CT.[DamageCategoryID],
CT.[CategoryName],
DG.[DamageGroupID],
DG.[DamageCategoryID],
DG.[GroupName],
DC.[DamageCodeID],
DC.[DamageGroupID],
DC.[DamageCodeName]
FROM
[dbo].[DamageCategory] AS CT
INNER JOIN [dbo].[DamageGroup] AS DG ON CT.[DamageCategoryID] = DG.[DamageCategoryID]
INNER JOIN [dbo].[DamageCode] AS DC ON DG.[DamageGroupID] = DC.[DamageGroupID]
WHERE
DC.[DamageCodeName] LIKE '%Bubble%'
This is where query syntax shines.
from dc in _contextDB.DamageCategories
from dg in dc.DamageGroups
from dc in dg.DamageCodes
where dc.DamageCodeName.Contains("Bubble")
select new
{
dc.DamageCategoryID,
dc.CategoryName,
dg.DamageGroupID,
dg.DamageCategoryID,
dg.GroupName,
dc.DamageCodeID,
dc.DamageGroupID,
dc.DamageCodeName
}
The query shape from ... from is the query syntax equivalent of SelectMany.
You use ToLower in your code. That may not be necessary. The query is translated into SQL and if the database field has a case-insensitive collation you don't need ToLower.
I have two Entity Framework Core entities:
public class JobOrder {
public int Id { get; set; }
public string JobTitle { get; set; }
public string Status { get; set; }
...
public IEnumerable<JobOrderUser> JobOrderUsers { get; set; }
}
public class JobOrderUser {
public int AppUserId { get; set; }
public AppUser User { get; set; }
public int JobOrderId { get; set; }
public JobOrder JobOrder { get; set; }
}
The second one is a join table used for a many-to-many between the JobOrder and User tables but I don't need to drill to the User table for this.
I want to get a collection of JobOrders that have an association with a specific user. In SQL, I would write something like this:
select distinct
a.*
from
JobOrders a
join JobOrderUser b on a.JobOrderID = b.JobOrderId
where
b.AppUserId = someId
How do I do that using LINQ method syntax?
If your entities are set up correctly, and their relationships are intact, you could load the JobOrderUsers while querying for a JobOrder and then filter by a user. Something like
JobOrder.Include(t => t.JobOrderUsers).Where(t => t.JobOrderUsers.Any(x => x.User.Id == SomeId));
You can also use the below query using join and Select the required columns data in a jobOrdersDto class. For that, you have to inject the _jobOrdersRepository and _jobOrderUserRepository repositories to your service where you are calling the required method.
var result = (from jobOrders in _jobOrdersRepository.GetAll()
join jobOrderUser in _jobOrderUserRepository.GetAll() on jobOrders.JobOrderID equals jobOrderUser.JobOrderId
where
(jobOrderUser.AppUserId == someId)
select new jobOrdersDto
{
}
Your Service class:
public class YourService
{
private readonly IRepository<jobOrders> _jobOrdersRepository;
private readonly IRepository<jobOrderUser> _jobOrderUserRepository;
public YourService(
IRepository<jobOrders> jobOrdersRepository, IRepository<jobOrderUser> jobOrderUserRepository)
: base()
{
_jobOrdersRepository = jobOrdersRepository;
_jobOrderUserRepository = jobOrderUserRepository;
}
}
I am trying to find one or more documents in RavenDB based on the values of a child collection.
I have the following classes
public class GoldenDocument
{
public GoldenDocument()
{
LinkedDocuments = new List<LinkedDocument>();
MergeMatchFields = new List<MergeMatchField>();
}
public string Id { get; set; }
public Guid SourceRowId { get; set; }
public List<MergeMatchField> MergeMatchFields { get; set; }
public List<LinkedDocument> LinkedDocuments { get; set; }
}
And the class that is in the collection MergeMatchFields
public class MergeMatchField
{
public string Id { get; set; }
public Guid OriginId { get; set; }
public string Name { get; set; }
public MatchType MatchType { get; set; }
public double MatchPerc { get; set; }
public string Value { get; set; }
}
In a List<MergeFields> mergeFields collection I have values that is not stored in RavenDB yet. Values are compared to values in a RavenDB document for find if it is a possible match by executing the following query:
using (var session = documentStore.OpenSession())
{
var docs = from gd in session.Query<GoldenDocument>()
from mf in gd.MergeMatchFields
from tf in mergeFields
where mf.Name == tf.Name
&& JaroWinklerCalculator.jaroWinkler(mf.Value, tf.Value) > .90d
&& !string.IsNullOrEmpty(mf.Value)
select gd;
}
I understand that ravenDB does not support SelectMany() so how would I go about getting the results from the Document store?
Create an index for this that would output the values you want to query on.
Note that you can't just execute arbitrary code the way you do here: JaroWinklerCalculator.jaroWinkler(mf.Value, tf.Value) > .90d
But you can use fuzzy queries, and they will do the same.
I've got CodeFirst collection defined as defined below.
For any given EmailOwnerId, I want to count the number of EmailDetailAttachments records exist without actually downloading all the images themselves.
I know I can do something like
var emailsToView = (from data in db.EmailDetails.Include("EmailDetailAttachments")
where data.EmailAccount.EmailOwnerId = 999
select data).ToList();
int cnt = 0;
foreach (var email in emailsToView)
{
cnt += email.EmailDetailAttachments.Count();
}
but that means I've already downloaded all the bytes of images from my far away server.
Any suggestion would be appreciated.
public class EmailDetail
{
[Key]
[DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)]
public int Id { get; set; }
public int EmailOwnerId {get;set;}
public virtual ICollection<ImageDetail> EmailDetailAttachments { get; set; }
..
}
public class ImageDetail
{
[Key]
[DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)]
public int Id { get; set; }
[MaxLengthAttribute(256)]
public string FileName { get; set; }
[MaxLengthAttribute(256)]
public string ContentMimeType { get; set; }
public byte[] ImageDataBytes { get; set; }
public DateTime ImageCreation { get; set; }
}
The engine should be able to update this to a COUNT(*) statement.
var emailsToView = (from data in db.EmailDetails // no Include
where data.EmailAccount.EmailOwnerId = 999
select new {
Detail = data,
Count=data.EmailDetailAttachments.Count() }
).ToList();
But you'll have to verify if this produces the right (and more efficient) SQL.