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Dynamic where clause (OR) in Linq to Entities
(2 answers)
Closed 5 years ago.
I am working in ASP.NET MVC, I have a scenario where user can select multiple options to get list of doctors, this is how my action looks like.
public JsonResult DoctorsList(int? specialization , int? city, int? area, int? insurance_company, string doctor_name )
Any of these arguments can have some value and any number of them can be null also all of can be null in that I will return all the records.
Now I know a long and complicated way where I can make different combinations of these arguments and check which one is null and which one is not and then write my query based on that.
But is there any other shorter more efficient way?
Right now I am using OR conditions to get records like this
var doctors = db.Doctors.Where(e =>
e.specialization == specialization ||
e.Clinics.FirstOrDefault(cs => cs.doctor_id == e.doctor_id).Area.city_id == city ||
e.Clinics.FirstOrDefault(cs => cs.doctor_id == e.doctor_id).area_id == area ||
e.Clinics.FirstOrDefault(cs => cs.doctor_id == e.doctor_id).ClinicInsuranceCompanies
.Select(sin=>sin.company_id).ToList().Contains(insurance_company) ||
e.first_name == doctor_name ||
e.last_name == doctor_name
)
.Select(s => new
{
doctor_name = s.first_name + " " + s.last_name
}).ToList();
But I want it to work in combinations, For Example Selecting Doctors with specialization_id = 1 and city_id=2 , of other combinations like this. But OR condition will be true if only one condition matches
For your scenario i think this approach might work rather than going around if else conditions. And i think && should be used to filter out exactly but you could use || operator if thats what you want,
var doctors = db.Doctors.Where(e =>
(specialization != null && e.specialization == specialization) &&
(city != null && e.Clinics.FirstOrDefault(cs => cs.doctor_id == e.doctor_id).Area.city_id == city) &&
(area != null && e.Clinics.FirstOrDefault(cs => cs.doctor_id == e.doctor_id).area_id == area) &&
(insurance_company != null && e.Clinics.FirstOrDefault(cs => cs.doctor_id == e.doctor_id).ClinicInsuranceCompanies
.Select(sin => sin.company_id).ToList().Contains(insurance_company)) &&
(doctor_name != "" && e.first_name == doctor_name || e.last_name == doctor_name)
)
.Select(s => new
{
doctor_name = s.first_name + " " + s.last_name
}).ToList();
This is what I was looking for #imanshu15 answer gave me a hint.
var doctors = db.Doctors.Where(e =>
(specialization != null && e.specialization == specialization) || (specialization == null)
).Where(e =>
(city != null && e.Clinics.FirstOrDefault(cs => cs.doctor_id == e.doctor_id).Area.city_id == city) || (city == null)
).Where(e =>
(area != null && e.Clinics.FirstOrDefault(cs => cs.doctor_id == e.doctor_id).area_id == area) || (area == null)
).Where(e =>
(insurance_company != null && e.Clinics.FirstOrDefault(cs => cs.doctor_id == e.doctor_id).ClinicInsuranceCompanies
.Select(sin => sin.company_id).ToList().Contains(insurance_company)) || (insurance_company == null)
).Where(e =>
(doctor_name != null && e.first_name == doctor_name) || (doctor_name == null)
)
Related
I have a query that select all Photos if its public, and only if friends if visibility is private in this code.
_communityDbContext
.Photos
.Where(x => (
x.Privacy == 1 ||
(x.Privacy == 2 &&
_communityDbContext.Friendships.FirstOrDefault(d => x.CreatedBy.Id == user1 && d.FriendUser.Id == user2) !=
null)
)
);
But I trying to extract this piece of code to reuse in another queries
_communityDbContext.Friendships.FirstOrDefault(d => x.CreatedBy.Id == user1 && d.FriendUser.Id == user2) != null
Is possible to call an function and make the code like that:
_communityDbContext
.Photos
.Where(x => (
x.Privacy == 1 ||
(x.Privacy == 2 &&
hasFriendship(x.CreatedBy.Id, user))
)
);
I fond a solution, the method invocation must be done to an expression, not to a function call. So I can extract that part of code by doing
public Expression<Func<Photo, bool>> Visible()
{
return x => (
x.Privacy == 1 ||
(x.Privacy == 2 &&
_communityDbContext.Friendships.FirstOrDefault(d => x.CreatedBy.Id == 3 && d.FriendUser.Id == 3) !=
null)
);
}
And calling this by
.where(Visible())
I have created two views that return exactly the same columns from the same tables. The only difference between the two views is they filter on different parameters. I have added these into my .dbml file
(Picture of views in dbml) This has then auto generated two classes for these two views.
In my code depending on the value of the property Filter one of the two views is queried, either current or previous. I need these views to be returned as the same type. So that IOrderedQueryable<> items has one return type.
Currently they are returning as either clientOrdersQueryCurrent or clientOrdersQueryPrevious. If I set IOrderedQueryable<> items to either one of these and attempt to cast the other type then this causes a runtime error.
IOrderedQueryable<> items;
bool filterQuery = false;
if (!string.IsNullOrEmpty(OrderNumber) || DateFrom != null || Dateto != null || !string.IsNullOrEmpty(TrackingNumber) || UserId != null)
{
filterQuery = true;
}
if (Filter == "Current")
{
if (filterQuery)
{
items = dataContext.clientOrdersQueryCurrents.Where(o => o.client_id == currentClientIdProvider.GetCurrentClientId()
&& (string.IsNullOrEmpty(OrderNumber) || o.OrderNumber.Contains(OrderNumber))
&& (DateFrom == null || o.OrderPlaced >= DateFrom)
&& (Dateto == null || o.OrderPlaced <= Dateto)
&& (string.IsNullOrEmpty(TrackingNumber) || o.TrackingReference.Contains(TrackingNumber))
&& (UserId == null || o.UserId == UserId)).OrderByDescending(o => o.OrderPlaced);
}
else
{
items = dataContext.clientOrdersQueryCurrents.Where(o => o.client_id == currentClientIdProvider.GetCurrentClientId()).OrderByDescending(o => o.OrderPlaced);
}
}
else if (Filter == "Previous")
{
if (filterQuery)
{
items = dataContext.clientOrdersQueryPrevious.Where(o => o.client_id == currentClientIdProvider.GetCurrentClientId()
&& (string.IsNullOrEmpty(OrderNumber) || o.OrderNumber.Contains(OrderNumber))
&& (DateFrom == null || o.OrderPlaced >= DateFrom)
&& (Dateto == null || o.OrderPlaced <= Dateto)
&& (string.IsNullOrEmpty(TrackingNumber) || o.TrackingReference.Contains(TrackingNumber))
&& (UserId == null || o.UserId == UserId)).OrderByDescending(o => o.OrderPlaced);
}
else
{
items = dataContext.clientOrdersQueryPrevious.Where(o => o.client_id == currentClientIdProvider.GetCurrentClientId()).OrderByDescending(o => o.OrderPlaced);
}
}
else
{
//Default call - current orders
items = dataContext.clientOrdersQueryCurrents.Where(o => o.client_id == currentClientIdProvider.GetCurrentClientId()).OrderByDescending(o => o.OrderPlaced);
}
The only thing I can currently think of to resolve this is to create a class and have the query map the result to the class after it returns.
What is the best way to do this?
The ORM I am currently using is NHibernate.
Better to map to some common class
IOrderedQueryable<CommonItem> items;
items = dataContext.clientOrdersQueryCurrents.Select(e => new CommonItem{...});
...
items = dataContext.clientOrdersQueryPrevious.Select(e => new CommonItem{...});
It can be AutoMapper's ProjectTo method
items = dataContext.clientOrdersQueryPrevious.ProjectTo<CommonItem>();
I'm struggling with data searching algorithm, which has to retrieve some data from the database using multiple fields. Each textbox provides a given parameter, stored in the database, accessed by Entity Framework. It's working when I enter data to all fields but if I leave any field empty it doesn't retrieve any record.
My question is - How to handle empty fields. If I leave any field without data, it should just not consider this parameter during selecting from the database and select data basing on non-null parameters.
This is what I've created so far:
[HttpPost]
public ViewResult Search(string brand, string model, int? manufactDateMin,
int? manufactDateMax, int? priceMin, int? priceMax, int? engineCapMin,
int? engineCapMax, string engineType, int page = 1)
{
IEnumerable<Car> foundItems = repository.Cars
.Where(c => brand == null || c.Brand == brand)
.Where(c => model == null || c.Model == model)
.Where(c => manufactDateMin == null || manufactDateMax == null || (c.ManufactDate.Year >= manufactDateMin) && (c.ManufactDate.Year < manufactDateMax))
.Where(c => priceMin == null || priceMax == null || (c.Price >= priceMin) && (c.Price < priceMax))
.Where(c => engineCapMin == null || engineCapMax == null || (c.EngineCapacity >= engineCapMin) && (c.EngineCapacity < engineCapMax))
.Where(c => engineType == null || c.EngineType == engineType)
.OrderBy(c => c.Id)
.Skip(PageSize * (page - 1))
.Take(PageSize);
CarListViewModel VMmodel = new CarListViewModel
{
Cars = foundItems,
PagingInfo = new PagingInfo
{
CurrentPage = page,
ItemsPerPage = PageSize,
TotalItems = foundItems.Count(),
},
CarType = null
};
return View("List", VMmodel);
}
Dont use a new where statement for each comparison. combine them into one. separate them into a new line for readability. Also, your parameters are defined as strings but your comparing it to null. You will have to pass a null for this to work. If you are passing the contents of a textbox or something then the string will be "" and not a null.
.Where(c => brand == "" || c.Brand == brand) &&
(model == "" || c.Model == model) &&
((manufactDateMin == null || manufactDateMax == null || (c.ManufactDate.Year >= manufactDateMin) && (c.ManufactDate.Year < manufactDateMax)) &&
(priceMin == null || priceMax == null || (c.Price >= priceMin) && (c.Price < priceMax))) &&
(engineCapMin == null || engineCapMax == null || (c.EngineCapacity >= engineCapMin) && (c.EngineCapacity < engineCapMax))) &&
(engineType == "" || c.EngineType == engineType))
I think you should do it separately like this
IQueryable<Car> query = repository.Cars;
if (!string.IsNullOrEmpty(brand))
{
query = query.Where(x => x.Brand == brand);
}
if (!string.IsNullOrEmpty(model ))
{
query = query.Where(x => x.Model == model );
}
and after all of them you put the take and skyp, it is faster and more readable
hi guys i was using Dynamic SQL for search queries where i used to attach WHERE & AND clause piece by piece and form a statement, i recently came to below alternate for this, and life was amazing
cool alternates of Dynamic WHERE-Clause
Select * From tblEmployees
where EmployeeName = Coalesce(#EmployeeName, EmployeeName) AND
Department = Coalesce(#Department, Department ) AND
Designation = Coalesce(#Designation, Designation) AND
JoiningDate >= Coalesce(#StartDate, JoiningDate) AND
JoiningDate <= Coalesce(#EndDate, JoiningDate) AND
Salary >= Coalesce(#Salary, Salary)
now the issue is since i implemented entity framework i need to achieve same with Linq queries. i have nullable Byte type and nullable boolean which i am currently unable to handle
just like Coalesce my stupid attempt was
&& (s.Floors == deal.Floors.HasValue ? null : s.Floors)
below code not matching any results
[HttpPost]
public ActionResult Results(Deal deal, bool exactMatch)
{
List<Deal> deals;
if (exactMatch)
{
deals = dataBase.Deals.Where(s =>
(s.OwnerName.Contains(deal.OwnerName) || s.OwnerName == null)
&& (s.Rooms == deal.Rooms || s.Rooms == null)
&& (s.BathRooms == deal.BathRooms || s.BathRooms == null)
&& (s.Floors == deal.Floors || s.Floors == null)
&& (s.Builtin == deal.Builtin || s.Builtin == null)
&& (s.Kitchens == deal.Kitchens || s.Kitchens == null)
&& (s.DoubleUnit == deal.DoubleUnit || s.DoubleUnit == null)
&& (s.Corner == deal.Corner || s.Corner == null)
&& (s.Remarks.Contains(deal.Remarks) || s.Remarks == null)
).ToList();
}
else
{
deals = dataBase.Deals.Where(s =>
(s.OwnerName.Contains(deal.OwnerName) || s.OwnerName == null)
|| (s.Rooms == deal.Rooms || s.Rooms == null)
|| (s.BathRooms == deal.BathRooms || s.BathRooms == null)
|| (s.Floors == deal.Floors || s.Floors == null)
|| (s.Builtin == deal.Builtin || s.Builtin == null)
|| (s.Kitchens == deal.Kitchens || s.Kitchens == null)
|| (s.DoubleUnit == deal.DoubleUnit || s.DoubleUnit == null)
|| (s.Corner == deal.Corner || s.Corner == null)
|| (s.Remarks.Contains(deal.Remarks) || s.Remarks == null)
).ToList();
}
return View(deals);
}
table has values like
id Bathroom Floors
1 1 2
2 1 4
3 2 6
4 3 1
i need results which has id 1 & 2
for instance in front end user want to only fill bathroom field with "1" and leave floor field empty
Not really the same. In your query your coalesce is on the parameter then taking the record value as the default if it is null. In your c# lambda you are checking if the parameter is the same as the table value and then checking if the table value is null but that omits the possibility of having a null value in the parameter.
Example
Sql
Department = Coalesce(#Department, Department )
would be
(s.Department == deal.Department || deal.Department == null)
not this which is what you have now
(s.Department == deal.Department || s.Department == null)
Edit
If you wanted to duplicate the COALESCE expression you have now you could write it this way although I am not sure if it would decrease efficiency / performance.
(s.Department == (deal.Department ?? s.Department))
You are testing whether the field in the table equals the 'deal' property or the field is null rather than doing this:
s.Remarks.Contains(deal.Remarks) || deal.Remarks == null
If you do this, it should be the equivalent query.
You can do this cumulatively too. For example with the exact match case you can do:
deals = dataBase.Deals;
if (deal.OwnerName != null)
deals = deals.Where(s => s.OwnerName.Contains(deal.OwnerName));
if (deal.Rooms != null)
deals = deals.Where(s => s.Rooms == deal.Rooms)
That can make the resulting query more efficient. There's a similar way to do this with the non exact match through using unions. I don't know the syntax off hand.
I am trying to get the result based upon the values of variables temp_DestinationGroupName, temp_CountryName and temp_RateTypeId.
If any of these variables are null or 0, it should not be included in where clause and rest statements should work and bring the result. I am getting zero rows using this query. Kindly suggest me something with these conditions in where clause. i tried following solutions on stackoverflow but still not getting the desired result.
var Rows = _CustomerRatesList.Where(w => (w.Id != rates.Id)
&& (w.DestinationGroupName == temp_DestinationGroupName || temp_DestinationGroupName!= null)
&& (w.CountryName == temp_CountryName || temp_CountryName!=null)
&& (w.RateTypeId == temp_RateTypeId || temp_RateTypeId !=0));
(w.DestinationGroupName == temp_DestinationGroupName || temp_DestinationGroupName!= null)
Your condition here will return true as long as your input variable temp_DestinationGroupName is not null. I don't think that's what you had in mind.
You can split in many Where to make your request more readable :
var Rows = _CustomerRatesList.Where(w => w.Id != rates.Id)
.Where(w => w.DestinationGroupName != temp_DestinationGroupName || temp_DestinationGroupName != null)
.Where(w => w.CountryName != temp_CountryName || temp_CountryName != null)
.Where(w => w.RateTypeId != temp_RateTypeId || temp_RateTypeId !=0);
Notice that you must use != in first conditioon of all Where, so you'll get all data except when it's null. In your logic, may be the conditions will be == :
var Rows = _CustomerRatesList.Where(w => w.Id != rates.Id)
.Where(w => w.DestinationGroupName == temp_DestinationGroupName || temp_DestinationGroupName == null)
.Where(w => w.CountryName == temp_CountryName || temp_CountryName == null)
.Where(w => w.RateTypeId == temp_RateTypeId || temp_RateTypeId ==0);
Each Where result is an IEnumerable, Rows will be a IEnumerable. If you want a List, just add .ToList()
I got the solution to this problem, now i am getting filtered result.
Thank you all for your time :)
var otherRows = _CustomerRatesList.Where(w => w.Id != rates.Id)
.Where(w => w.DestinationGroupName == temp_DestinationGroupName || temp_DestinationGroupName == null)
.Where(w => w.CountryName == temp_CountryName || temp_CountryName == null)
.Where(w => w.RateTypeId == temp_RateTypeId || temp_RateTypeId == 0);