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Linq2Entities query to find records given mix-max range

I have those two entities:
public class Ticket
{
public int Id { get; set; }
public int ScheduleId { get; set; }
public int SeatId { get; set; }
[DataType(DataType.Date)]
[Column(TypeName = "Date")]
[DisplayFormat(DataFormatString = "{0:yyyy-MM-dd}", ApplyFormatInEditMode = true)]
public DateTime ForDate { get; set; }
public Seat Seat { get; set; }
public Schedule Schedule { get; set; }
public ICollection<TicketStop> TicketStops { get; set; }
}
public class TicketStop
{
public int Id { get; set; }
public int TicketId { get; set; }
public int LineStopStationId { get; set; }
public Ticket Ticket { get; set; }
public LineStopStation LineStopStation { get; set; }
}
public class LineStopStation
{
public int Id { get; set; }
public int LineId { get; set; }
public int StopId { get; set; }
public int Order { get; set; }
public bool IsLastStop { get; set; }
public Line Line { get; set; }
public Stop Stop { get; set; }
}
The business case is that I am implementing a bus ticket reservation system (for learning purposes mostly) and I want to find overlapping tickets.
The combination of LineId + ScheduleId + ForDate identifies uniquely that that a ticket is for certain bus at a certain date and departure time.
The problem I have is to identify, given starting and end location whether or not two tickets overlap for one or more stops.
The LineStopStation entity holds information about the StopId and the Order in which it is visited during the bus trip. So basically, overlapping tickets will have same Order number at some point (unless it is the last stop, which means that the passenger is leaving the bus).
So what I have is LineId, ScheduleId, StartId and EndId where starId and endId correspond to LineStopStation.StopId so eventually I am able to get the Order out of them like this.
int startStationOrder = _context.LineStopStations
.First(l => l.LineId == lineId && l.StopId == startId).Order;
int endStationOrder = _context.LineStopStations
.First(l => l.LineId == lineId && l.StopId == endId).Order;
So I am pretty convinced that having all this information I should be able to find if in TicketStop table I have ticket which overlaps with the data in question. TicketStop works this way - if someone bought a ticket for 3 stops I will have three records there with the same TicketId and three different LineStopStationId.
I feel that this question got a bigger than needed. So basically I have this:
public List<Seat> GetAvailableSeats(int lineId, int scheduleId, int startId, int endId, DateTime forDate)
{
int startStationOrder = _context.LineStopStations
.First(l => l.LineId == lineId && l.StopId == startId).Order;
int endStationOrder = _context.LineStopStations
.First(l => l.LineId == lineId && l.StopId == endId).Order;
var reservedSeats = _context.TicketStops
.Where(t => t.Ticket.ScheduleId == scheduleId)
.Where(t => t.Ticket.ForDate == forDate)
//basically I don't know how to proceed here.
//In pseudo code it should be something like:
.Where(t => t.Min(Order) >= endStationOrder || t.Max(Order) <= startStationOrder
}
But obs. this is not how LINQ works. So how can I find all tickets where this range overlaps?

Without an in-depth analysis of your model, perhaps something like this could give you an idea?
var reservedSeats = _context.TicketStops
.GroupBy(t => new { t.Ticket.ScheduleId, t.Ticket.ForDate })
.Where(tg => tg.Key == new { ScheduleId = scheduleId, ForDate = forDate })
.Where(tg => tg.Min(t => t.LineStopStation.Order) >= endStationOrder || tg.Max(t => t.LineStopStation.Order) <= startStationOrder);
You could also filter first and do an empty GroupBy:
var reservedSeats = _context.TicketStops
.Where(t => t.Ticket.ScheduleId == scheduleId && t.Ticket.ForDate == forDate)
.GroupBy(t => 1)
.Where(tg => tg.Min(t => t.LineStopStation.Order) >= endStationOrder || tg.Max(t => t.LineStopStation.Order) <= startStationOrder);
To return all the SeatIds, you just need to select them from the group.
var reservedSeats = _context.TicketStops
.Where(t => t.Ticket.ScheduleId == scheduleId && t.Ticket.ForDate == forDate)
.GroupBy(t => 1)
.Where(tg => tg.Min(t => t.LineStopStation.Order) >= endStationOrder || tg.Max(t => t.LineStopStation.Order) <= startStationOrder);
.SelectMany(tg => tg.Select(t => t.Ticket.SeatId));

How to merge object properties of the same class together via LINQ

Say I have a class, I want to select multiple objects of it but create one unified object in the end. This is because of the requirement for the collection properties of the object to be combined.
using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Linq;
using Microsoft.EntityFrameworkCore.Internal;
using Nozomi.Base.Core;
namespace Nozomi.Data.Models.Currency
{
public class Currency : BaseEntityModel
{
public Currency(ICollection<Currency> currencies)
{
if (currencies.Any())
{
var firstCurr = currencies.FirstOrDefault();
if (firstCurr != null)
{
// Doesn't matter...
Id = firstCurr.Id;
CurrencyTypeId = firstCurr.Id;
CurrencyType = firstCurr.CurrencyType;
Abbrv = firstCurr.Abbrv;
Name = firstCurr.Name;
CurrencySourceId = firstCurr.CurrencySourceId;
CurrencySource = firstCurr.CurrencySource;
WalletTypeId = firstCurr.WalletTypeId;
PartialCurrencyPairs = currencies
.SelectMany(c => c.PartialCurrencyPairs)
.DefaultIfEmpty()
.ToList();
}
}
}
[Key]
public long Id { get; set; }
public long CurrencyTypeId { get; set; }
public CurrencyType CurrencyType { get; set; }
public string Abbrv { get; set; } // USD? MYR? IND?
public string Name { get; set; }
public long CurrencySourceId { get; set; }
public Source CurrencySource { get; set; }
// This will have a number if it is a crypto pair to peg to proper entities
public long WalletTypeId { get; set; } = 0;
public ICollection<PartialCurrencyPair> PartialCurrencyPairs { get; set; }
public bool IsValid()
{
return !String.IsNullOrEmpty(Abbrv) && !String.IsNullOrEmpty(Name) && CurrencyTypeId > 0 && CurrencySourceId > 0;
}
}
}
Here's what a PartialCurrencyPair is:
namespace Nozomi.Data.Models.Currency
{
/// <summary>
/// Partial currency pair.
/// </summary>
public class PartialCurrencyPair
{
public long CurrencyId { get; set; }
public long CurrencyPairId { get; set; }
public bool IsMain { get; set; } = false;
public CurrencyPair CurrencyPair { get; set; }
public Currency Currency { get; set; }
}
}
So basically, if you want to make EURUSD, you'll have to take two currencies to form a pair. A CurrencyPair is made up of two PartialCurrencyPairs. The reason why we can have many EUR or many USDs is that they come from different sources.
Here's what a CurrencyPair is:
public class CurrencyPair : BaseEntityModel
{
[Key]
public long Id { get; set; }
public CurrencyPairType CurrencyPairType { get; set; }
/// <summary>
/// Which CPC to rely on by default?
/// </summary>
public string DefaultComponent { get; set; }
public long CurrencySourceId { get; set; }
public Source CurrencySource { get; set; }
// =========== RELATIONS ============ //
public ICollection<CurrencyPairRequest> CurrencyPairRequests { get; set; }
public ICollection<WebsocketRequest> WebsocketRequests { get; set; }
public ICollection<PartialCurrencyPair> PartialCurrencyPairs { get; set; }
public bool IsValid()
{
var firstPair = PartialCurrencyPairs.First();
var lastPair = PartialCurrencyPairs.Last();
return (CurrencyPairType > 0) && (!string.IsNullOrEmpty(APIUrl))
&& (!string.IsNullOrEmpty(DefaultComponent))
&& (CurrencySourceId > 0)
&& (PartialCurrencyPairs.Count == 2)
&& (firstPair.CurrencyId != lastPair.CurrencyId)
&& (!firstPair.IsMain == lastPair.IsMain);
}
}
I have an IQueryable to combine into one single currency.
Code with comments (The comments basically tells you what I'm trying to achieve.
var query = _unitOfWork.GetRepository<Currency>()
.GetQueryable()
// Do not track the query
.AsNoTracking()
// Obtain the currency where the abbreviation equals up
.Where(c => c.Abbrv.Equals(abbreviation, StringComparison.InvariantCultureIgnoreCase)
&& c.DeletedAt == null && c.IsEnabled)
// Something here that will join the PartialCurrencyPair collection together and create one single Currency object.
.SingleOrDefault();
How do I come about it? Thank you so much in forward! Here's the
progress I've made so far and it works, but I'm pretty LINQ has a beautiful way to make this better and optimised:
var combinedCurrency = new Currency(_unitOfWork.GetRepository<Currency>()
.GetQueryable()
// Do not track the query
.AsNoTracking()
// Obtain the currency where the abbreviation equals up
.Where(c => c.Abbrv.Equals(abbreviation, StringComparison.InvariantCultureIgnoreCase)
&& c.DeletedAt == null && c.IsEnabled)
.Include(c => c.PartialCurrencyPairs)
.ThenInclude(pcp => pcp.CurrencyPair)
.ThenInclude(cp => cp.CurrencyPairRequests)
.ThenInclude(cpr => cpr.RequestComponents)
.ThenInclude(rc => rc.RequestComponentDatum)
.ThenInclude(rcd => rcd.RcdHistoricItems)
.ToList());
return new DetailedCurrencyResponse
{
Name = combinedCurrency.Name,
Abbreviation = combinedCurrency.Abbrv,
LastUpdated = combinedCurrency.PartialCurrencyPairs
.Select(pcp => pcp.CurrencyPair)
.SelectMany(cp => cp.CurrencyPairRequests)
.SelectMany(cpr => cpr.RequestComponents)
.OrderByDescending(rc => rc.ModifiedAt)
.FirstOrDefault()?
.ModifiedAt ?? DateTime.MinValue,
WeeklyAvgPrice = combinedCurrency.PartialCurrencyPairs
.Select(pcp => pcp.CurrencyPair)
.Where(cp => cp.CurrencyPairRequests
.Any(cpr => cpr.DeletedAt == null && cpr.IsEnabled))
.SelectMany(cp => cp.CurrencyPairRequests)
.Where(cpr => cpr.RequestComponents
.Any(rc => rc.DeletedAt == null && rc.IsEnabled))
.SelectMany(cpr => cpr.RequestComponents
.Where(rc =>
rc.ComponentType.Equals(ComponentType.Ask) ||
rc.ComponentType.Equals(ComponentType.Bid)))
.Select(rc => rc.RequestComponentDatum)
.SelectMany(rcd => rcd.RcdHistoricItems
.Where(rcdhi => rcdhi.CreatedAt >
DateTime.UtcNow.Subtract(TimeSpan.FromDays(7))))
.Select(rcdhi => decimal.Parse(rcdhi.Value))
.DefaultIfEmpty()
.Average(),
DailyVolume = combinedCurrency.PartialCurrencyPairs
.Select(pcp => pcp.CurrencyPair)
.Where(cp => cp.CurrencyPairRequests
.Any(cpr => cpr.DeletedAt == null && cpr.IsEnabled))
.SelectMany(cp => cp.CurrencyPairRequests)
.Where(cpr => cpr.RequestComponents
.Any(rc => rc.DeletedAt == null && rc.IsEnabled))
.SelectMany(cpr => cpr.RequestComponents
.Where(rc => rc.ComponentType.Equals(ComponentType.VOLUME)
&& rc.DeletedAt == null && rc.IsEnabled))
.Select(rc => rc.RequestComponentDatum)
.SelectMany(rcd => rcd.RcdHistoricItems
.Where(rcdhi => rcdhi.CreatedAt >
DateTime.UtcNow.Subtract(TimeSpan.FromHours(24))))
.Select(rcdhi => decimal.Parse(rcdhi.Value))
.DefaultIfEmpty()
.Sum(),
Historical = combinedCurrency.PartialCurrencyPairs
.Select(pcp => pcp.CurrencyPair)
.SelectMany(cp => cp.CurrencyPairRequests)
.SelectMany(cpr => cpr.RequestComponents)
.Where(rc => componentTypes != null
&& componentTypes.Any()
&& componentTypes.Contains(rc.ComponentType)
&& rc.RequestComponentDatum != null
&& rc.RequestComponentDatum.IsEnabled
&& rc.RequestComponentDatum.DeletedAt == null
&& rc.RequestComponentDatum.RcdHistoricItems
.Any(rcdhi => rcdhi.DeletedAt == null &&
rcdhi.IsEnabled))
.ToDictionary(rc => rc.ComponentType,
rc => rc.RequestComponentDatum
.RcdHistoricItems
.Select(rcdhi => new ComponentHistoricalDatum
{
CreatedAt = rcdhi.CreatedAt,
Value = rcdhi.Value
})
.ToList())
};
Here's the end result I want on that single object: A DetailedCurrencyResponse object.
public class DistinctiveCurrencyResponse
{
public string Name { get; set; }
public string Abbreviation { get; set; }
public DateTime LastUpdated { get; set; }
public decimal WeeklyAvgPrice { get; set; }
public decimal DailyVolume { get; set; }
}
A historical datum is basically a kvp, where the Key (ComponentType) is an enum.
public class DetailedCurrencyResponse : DistinctiveCurrencyResponse
{
public Dictionary<ComponentType, List<ComponentHistoricalDatum>> Historical { get; set; }
}
public class ComponentHistoricalDatum
{
public DateTime CreatedAt { get; set; }
public string Value { get; set; }
}

The query you have outlined will attempt to return you a single Currency object, but given you are looking for any with a given abbreviation, if multiple currency objects share an abbreviation, the SingleOrDefault could error due to multiple returns.
It sounds like you want to define a structure to represent the currency pairs. That structure is not a Currency entity, but a different data representation. These are commonly referred to as ViewModels or DTOs. Once you've defined what you want to return, you can use .Select() to populate that from the Currency and applicable abbreviations.
For instance, if I create a CurrencySummaryDto which will have the currency ID, Abbrevation, and a string containing all of the applicable pairs:
public class CurrencySummaryDto
{
public long CurrencyId { get; set; }
public string Abbreviation { get; set; }
public string Pairs { get; set;}
}
... then the query...
var currencySummary = _unitOfWork.GetRepository<Currency>()
.GetQueryable()
.AsNoTracking()
.Where(c => c.Abbrv.Equals(abbreviation, StringComparison.InvariantCultureIgnoreCase)
&& c.DeletedAt == null && c.IsEnabled)
.Select( c => new {
c.Id,
c.Abbrv,
Pairs = c.PartialCurrencyPairs.Select(pc => pc.PairName).ToList() // Get names of pairs, or select another annonymous type for multiple properties you care about...
}).ToList() // Alternatively, when intending for returning lots of data use Skip/Take for paginating or limiting resulting data.
.Select( c => new CurrencySummaryDto
{
CurrencyId = c.Id,
Abbreviation = c.Abbrv,
Pairs = string.Join(", ", c.Pairs)
}).SingleOrDefault();
This is if you want to do something like combine data from the currency pairs into something like a string. If you're happy to leave them as a collection of simplified data, then the extra anonymous type and .ToList() are not required, just select directly into the Dto structure. This example combines the data into a string where string.Join() is not supported in EF expressions so we have to get our data out into objects to hand over to Linq2Object for the final mapping.
Edit: Ok, you're requirement/example just got a whole lot more complicated with the pair structure, but you should be able to leverage this into the query rather than selecting the entire graph of entities by moving the selection of those values up into the main query... However...
Given the complexity of the data relationships, the approach I would recommend using since this would be assumed to be a read-only result, would be to construct a View in the database to flatten these averages and totals, then bind a simplified entity to this view rather than attempting to manage this with EF Linq. I believe it can be done with linq, but it will be quite onerous to look at, and a view-based summary entity would be a lot cleaner while keeping the execution of this logic to be executed in the database.

Get objects whose property does not exist in enumerable

Multiple answers have led me to the following 2 solutions, but both of them do not seem to be working correctly.
What I have are 2 objects
public class DatabaseAssignment : AuditableEntity
{
public Guid Id { get; set; }
public string User_Id { get; set; }
public Guid Database_Id { get; set; }
}
public class Database : AuditableEntity
{
public Guid Id { get; set; }
public string Name { get; set; }
public string Server { get; set; }
public bool IsActive { get; set; }
public Guid DatabaseClientId { get; set; }
}
Now, the front-end will return all selected Database objects (as IEnumerable) for a given user. I am grabbing all current DatabaseAssignments from the database for the given user and comparing them to the databases by the Database.ID property. My goal is to find the DatabaseAssignments that I can remove from the database. However, my solutions keep returning all DatabaseAssignments to be removed.
if (databases != null)
{
var unitOfWork = new UnitOfWork(_context);
var userDatabaseAssignments = unitOfWork.DatabaseAssignments.GetAll().Where(d => d.User_Id == user.Id);
//var assignmentsToRemove = userDatabaseAssignments.Where(ud => databases.Any(d => d.Id != ud.Database_Id));
var assignmentsToRemove = userDatabaseAssignments.Select(ud => userDatabaseAssignments.FirstOrDefault()).Where(d1 => databases.All(d2 => d2.Id != d1.Database_Id));
var assignmentsToAdd = databases.Select(d => new DatabaseAssignment { User_Id = user.Id, Database_Id = d.Id }).Where(ar => assignmentsToRemove.All(a => a.Database_Id != ar.Database_Id));
if (assignmentsToRemove.Any())
{
unitOfWork.DatabaseAssignments.RemoveRange(assignmentsToRemove);
}
if (assignmentsToAdd.Any())
{
unitOfWork.DatabaseAssignments.AddRange(assignmentsToAdd);
}
unitOfWork.SaveChanges();
}

I think u are looking for an Except extension, have a look at this link
LINQ: Select where object does not contain items from list
Or other way is with contains see below Fiddler link :
https://dotnetfiddle.net/lKyI2F

Select Filtered with LINQ and EF

I have a class like this, which is derived from a database with EF (my database contains all records from this class):
public class Products
{
public string color { get; set; }
public string size { get; set; }
public string comment { get; set; }
public string owner { get; set; }
public string buyer { get; set; }
public Nullable<DateTime> After { get; set; }
public Nullable<DateTime> Before { get; set; }
}
Now, on my web form users can specify each property in free text boxes and I want to search in the database entity, based on these properties. The user can decide to fill all properties, or may be just two of them. How do I create the .select in EF?
Any help welcome!
BR,
Ronald

Products.GetAllProducts().Where(x=>(string.IsNullOrEmpty(txtColor.Text) || x.color ==txtColor.Text) &&
(string.IsNullOrEmpty(txtSize) || x.size == txtSize.Text) &&
--- Same as other fields
).AsEnumerable();

Db.Products
.Where(p=>string.IsNullOrEmty(colorTexBox.Text) || p.color==colorTexBox.Text)
.Where(p=>check other property...)
.
.
.AsEnumerable()

Use .Contains method:
private bool IsMatch(string value, string searchCriteria)
{
if(searchCriteria == null || value == null) return true;
return value.ToUpper().Contains(searchCriteria.ToUpper());
}
public Products FindProducts(string color, string size, string comment, string owner, string buyer, datetime? after, datetime? before)
{
using(MyDbContext cont = new MyDbContext())
{
return cont.Products.Where((p) =>
{
return IsMatch(p. color, color) && IsMatch(p.size, size) &&
IsMatch(p.comment, comment) && IsMatch(p.owner, owner) &&
IsMatch(p.buter, buyer); // add your logic for dates here
});
}
}

Entity Framework Virtual ICollection How to Query

First of all, I am new to Entity Framework etc and trying to figure some things out. I have a model like this:
public class EventInstance {
[Column("EVENT_INSTANCE_ID")]
public int EventInstanceID { get; set; }
[Column("CUSTOMER_ID")]
public int CustomerID { get; set; }
[Column("EVENT_ID")]
public int EventID { get; set; }
[Column("START_DATE_TIME")]
public System.DateTime StartDateTime { get; set; }
public virtual Event Event { get; set; }
}
I need to access a property in a table called EventTimeEventInstances but this table is not included in the model. I have two questions.
If I add:
public virtual ICollection<EventTimeEventInstance> EventTimeInstances { get; set; }
Will that effect other areas of our application?
Secondly, how do I access the property from the ICollection in a query like this:
public IQueryable<EventInstance> GetInstances(int scheduleID) {
// only returning instances that are 3 months back
DateTime dateRange = DateTime.Now.AddDays(-180);
return EventDBContext.EventInstances.Where
(x => x.CustomerID == MultiTenantID && x.StartDateTime >= dateRange)
.OrderBy(x => x.StartDateTime).AsQueryable();
}
I need to be able to add EventTimeInstances.EventTimeID == scheudleID to this query. How can I do this?

You can use it like that in your query:
public IQueryable<EventInstance> GetInstances(int scheduleID)
{
// only returning instances that are 3 months back
DateTime dateRange = DateTime.Now.AddDays(-180);
return EventDBContext.EventInstances.Where(x =>
x.CustomerID == MultiTenantID &&
x.StartDateTime >= dateRange &&
x.EventTimeInstances.Any(a => a.EventTimeID == scheudleID) ).OrderBy(x => x.StartDateTime).AsQueryable();
}