I'm trying to write a query to select data from database. I have the following code :
from notes in ctx.Notes
.Where(x => x.UserId== user.UserId
|| x.UserId == user.FamilyId
|| x.UserId == user.CompanyId).DefaultIfEmpty()
The problem with this is that the FamilyId and CompanyId are both nullable types and may not have any value at all which corrupts the whole query. How can I rewrite it so it only looks for FamilyId/CompanyId if they have values?
Create condition query:
var users = ctx.Notes.Where(x => x.UserId == user.UserId);
if (user.FamilyId != null)
{
users = users.Union(ctx.Notes.Where(x => x.UserId == user.FamilyId));
}
if (user.CompanyId != null)
{
users = users.Union(ctx.Notes.Where(x => x.UserId == user.CompanyId ));
}
var result = users.ToArray();
Simple, just add an AND clause to check if it's not null:
from notes in ctx.Notes.Where(x => x.UserId== user.UserId || (user.FamilyId ! =null && x.UserId == user.FamilyId) || (user.CompanyId !=null && x.UserId == user.CompanyId)).DefaultIfEmpty()
Related
In the following GetByExpression, sometimes the r.branchid is null. How do I add a conditional in there so it utilises a different field (r.Invoice.Branch.Id) to check against when r.branchid is null?
var t = receiptRepo
.GetByExpression(r => r.BranchId == branchId)
.Where(r => r.Date == selectedDate && r.BatchId == null)
.ToList();
Use a ternary operation
(r.BranchId != null? r.BranchId:r.Invoice.Branch.Id ) == branchId //or whatever you want to compare
You can try using null-coalescing operator ??:
r => (r.BranchId ?? r.Invoice.BranchId) == branchId
Here if r.BranchId is null we use r.Invoice.BranchId to compare with branchId. Note, that we can chain ?? operators, e.g.
r => (r.BranchId ?? r.Invoice.BranchId ?? r.Bill.BranchId) == branchId
we try BranchId if it's null, we have a look at r.Invoice.BranchId and if it's null we get r.Bill.BranchId etc.
Your Linq query can be
var t = receiptRepo
.GetByExpression(r => (r.BranchId ?? r.Invoice.BranchId) == branchId)
.Where(r => r.Date == selectedDate && r.BatchId == null)
.ToList();
You can do this:
var t = receiptRepo
.GetByExpression(r => (r?.BranchId ?? r.Invoice.BranchId) == branchId)
.Where(r => r.Date == selectedDate && r.BatchId == null)
.ToList();
I created where conditions with linq lambda expression for reporting. My conditions are running very slowly or it is throwing error.
Error Detail: Evoluation timed out.
How can i find correct query?
My codes:
var query = Worker.Members
.Where(u => string.IsNullOrEmpty(model.TcNumber) || u.TcNumber.Contains(model.TcNumber))
.Where(u => string.IsNullOrEmpty(model.FullName) || u.FullName.Contains(model.FullName))
.Where(u => model.BirthYear == null || u.BirthDate.Year >= model.BirthYear)
.Where(u => model.BirthYearLevel == null || u.BirthDate.Year <= model.BirthYearLevel)
.Where(u => model.BirthYearLevel == null || u.BirthDate.Year <= model.BirthYearLevel)
.Where(u => model.GenderId == null || u.GenderId == model.GenderId)
.Where(u => model.DistrictCode == null || u.Contacts.Any(c => c.DistrictCode == model.DistrictCode && c.IsActive))
.Where(u => model.StreetCode == null || u.Contacts.Any(c => c.StreetCode == model.StreetCode && c.IsActive))
.Where(u => model.ExteriorDoor == null || u.Contacts.Any(c => c.ExteriorDoor == model.ExteriorDoor && c.IsActive))
.Where(u => model.InteriorDoor == null || u.Contacts.Any(c => c.InteriorDoor == model.InteriorDoor && c.IsActive))
.Where(u => model.DisabledGroupId == null || u.Disableds.Any(d => d.ReportDisabledGroups.Any(c => c.DisabledGroupId == model.DisabledGroupId)))
.Where(u => model.ContributionTypeId == null || u.Demands.Any(d => d.ContributionTypeId == model.ContributionTypeId && !d.IsDeleted))
.Where(u => model.DemandStatusId == null || u.Demands.Any(d => d.DemandStatusId == model.DemandStatusId && !d.IsDeleted))
.Where(u => model.DemandDateStart == null || u.Demands.Any(d => d.DemandDate >= model.DemandDateStart && !d.IsDeleted))
.Where(u => model.DemandDateEnd == null || u.Demands.Any(d => d.DemandDate <= model.DemandDateEnd && !d.IsDeleted))
.Where(u => u.IsTcCitizen == model.IsForeign)
.Where(u => u.IsDisabled == model.IsDisabled)
.Where(u => u.IsAlive == model.IsAlive);
The correct pattern (assuming Worker.Members is an IQueryable, not an IEnumerable) here is to conditionally add the criteria, like this:
var query = Worker.Members;
if (!string.IsNullOrEmpty(model.TcNumber))
query = query.Where(u => u.TcNumber.Contains(model.TcNumber));
if (!string.IsNullOrEmpty(model.FullName)
query = query.Where(u => u.FullName.Contains(model.FullName));
if (!model.BirthYear == null)
query = query.Where(u => u.BirthDate.Year >= model.BirthYear);
. . .
Did you check this?
Here detailed descriptions are given.
I want to do a query with lambda expression.
My database is a Cosmos DB.
I want to filter for two parameters and one of the two can be null.
For example i want to search for name and lastname and one of both is null.
This is that I am trying:
var result = this._client.CreateDocumentQuery<Person>(
UriFactory.CreateDocumentCollectionUri(_idDatabase, _idCollection), queryOptions)
.Where((f) => f.Name == Name && f.LastName == lastName )
.AsEnumerable()
.ToList();
So this?
var result = this._client.CreateDocumentQuery<Person>(
UriFactory.CreateDocumentCollectionUri(_idDatabase, _idCollection), queryOptions)
.Where((f) => (f.Name == Name || (f.Name == null && f.LastName != null)) && (f.LastName == lastName || (f.LastName == null && f.Name != null))
.AsEnumerable()
.ToList();
try something like this:
var result = this._client.CreateDocumentQuery<Person>(
UriFactory.CreateDocumentCollectionUri(_idDatabase, _idCollection), queryOptions)
.Where(f => f.Name == $"{Name ?? f.Name}") &&
f.LastName == $"{lastName ?? f.LastName}") )
.AsEnumerable()
.ToList();
Maybe you can work with IQueryable:
IQueryable<Person> iPerson = this._client.CreateDocumentQuery<Person>(
UriFactory.CreateDocumentCollectionUri(_idDatabase, _idCollection), queryOptions);
if(Name != null) iPerson = iPerson.Where(f => f.Name == Name);
if(lastName != null) iPerson = iPerson.Where(f => f.LastName == lastName)
return iPerson.AsEnumerable().ToList();
I need check if any record exists on current date. But AddOn is nullable date. If I check below condition is throwing error because I am trying get date from null.
var cusRelationships = SvcClient.Client.Context.CusRelationships.Where(c =>
c.CustomerId == identity.rCustomerId &&
c.AddedOn.Value.Date == DateTime.Now.Date).Select(c => c).ToList();
How compare date for current date?
Just check for null before the using the Value.
var cusRelationships = SvcClient.Client.Context.CusRelationships.Where(c =>
c.CustomerId == identity.rCustomerId &&
c.AddedOn.HasValue &&
c.AddedOn.Value.Date == DateTime.Now.Date).Select(c => c).ToList();
var cusRelationships = SvcClient.Client.Context.CusRelationships
.Where(c =>
c.CustomerId == identity.rCustomerId &&
c.AddedOn.HasValue &&
c.AddedOn.Value.ToShortDateString() == DateTime.Now.ToShortDateString())
.Select(c => c)
.ToList();
I have the below code which works but I do not feel this is the best way to achieve the result. I am looking at optimising my code. Any suggestions of a better option will be appreciated. sub is a subcategory which is nullable.
[AllowAnonymous]
public ActionResult _relatedgrps(string cat, string sub)
{
if (!string.IsNullOrWhiteSpace(sub)){
var pgs = db.Pages
.Where(u=>u.MetaNoSearch==false)
.Where(u => u.PaOk == true && u.Category.Name == cat && u.SubCategory.CatName == sub)
.OrderByDescending(u => u.PaCreatedOn);
return PartialView(pgs.ToList());
}else{
var pgs = db.Pages
.Where(u=>u.MetaNoSearch==false)
.Where(u => u.PaOk == true && u.Category.Name == cat )
.OrderByDescending(u => u.PaCreatedOn);
return PartialView(pgs.ToList());
}}
Linq IEnumerables can be additive and the query will only be executed when enumerated for the first time (like calling .ToList()). So you should be able to do something like this:
var pgs = db.Pages
.Where(u => u.MetaNoSearch == false &&
u.PaOk == true &&
u.Category.Name == cat);
if (!string.IsNullOrWhiteSpace(sub))
{
pgs = pgs.Where(u => u.SubCategory.CatName == sub);
}
return PartialView(pgs.OrderByDescending(u => u.PaCreatedOn).ToList());
Create an object to query it. To improve it, you also could remove it boolean comparations because they are conditions.
var query = db.Pages.Where(u => !u.MetaNoSearch && u.PaOk && u.Category.Name == cat);
if (!string.IsNullOrWhiteSpace(sub))
query = query.Where(u => u.SubCategory.CatName == sub);
query = query.OrderByDescending(u => u.PaCreatedOn);
return PartialView(query.ToList());
#user3021830 - be careful with String.IsNullOrWhitespace, you cannot use that in a database query. You could do String.IsNullOrWhitespace(sub), but not String.IsNullOrWhitespace(u.*).
I'd avoid any conditionals in the query because that will likely result in a case statement in the SQL.
To produce the best SQL I'd do something like this:
var pgs = db.Pages.Where(u => u.MetaNoSearch == false)
.Where(u => u.PaOk == true)
.Where(u => u.Category.Name == cat);
if (!string.IsNullOrWhiteSpace(sub))
{
pgs = pgs.Where(u => u.SubCategory.CatName == sub);
}
var result = pgs.OrderByDescending(u => u.PaCreatedOn).ToList();