I have a Table User(ID, Name....), Projects(ID, Name, Timestamps, IsFavorite...), Projects_Favoite(UserID, ProjectID)
I try to check for each projekt if there is a row for the current user. If there is a row I want set the "IsFavorite" in my Project true, otherwise false.
I tied:
for(int i = 0; i <= erg.Count();i++)
{
if (erg.ElementAt(i).User11.Any(u => u.Guid == ID) == true)
erg.ElementAt(i).SetFavorite = true;
}
but there is no way to use ElementAt, because it can't translated to SQL.
So I tried:
for(int i = 0; i <= erg.Count();i++)
{
if (erg.Take(i).Last().User11.Any(u => u.Guid == ID) == true)
erg.Take(i).Last().SetFavorite = true;
}
same problem here, so I tried:
foreach (Project project in erg)
{
if (project.User11.Any(u => u.Guid == ID))
project.SetFavorite = true;
}
There is the same problem. Is there a way to realise a ElementAt?
You should be able to do:
foreach (Project project in erg.Where(p => p.User11.Any(u => u.Guid == ID))
.ToList())
project.SetFavorite = true;
}
Assuming that erg is an IQuerable than you cannot use ElementAt as it is not supported (http://msdn.microsoft.com/en-us/library/bb399342.aspx check the section Operators With no translation), you can use it on a list though, but of course you will lose the benefits of the deferred query.
Try to use Skip instead
var whatyouwant = erg.Skip(index).First();
By looking at the stacktrace (can't read german though) looks there's something wrong with the SetFavorite column. Try first to remove this bit first:
project.SetFavorite = true;
then check also that your model columns match with what you got on the db.
Related
In various environment, the user name is case insensitive. We query admin equal to ADMIN. I have searched LiteDB called CompareTo to compare two objects that I can't find a point to make string compared as case insensitive.
The code in QueryEquals.cs
internal override IEnumerable<IndexNode> ExecuteIndex(IndexService indexer, CollectionIndex index)
{
var node = indexer.Find(index, _value, false, Query.Ascending);
if (node == null) yield break;
yield return node;
if (index.Unique == false)
{
// navigate using next[0] do next node - if equals, returns
while (!node.Next[0].IsEmpty && ((node = indexer.GetNode(node.Next[0])).Key.CompareTo(_value) == 0))
{
if (node.IsHeadTail(index)) yield break;
yield return node;
}
}
}
The propositional we can case insensitive
using (var db = new LiteRepository("lite.db"))
{
db.Insert(new User { Name = "John" });
var user = db.Query<User>()
.Where(x => x.Name == "JOHN")
.FirstOrDefault(); // proposal return John
var fail = db.Query<User>()
.Where(x => string.Equals(x.Name, "JOHN", StringComparison.OrdinalIgnoreCase))
.FirstOrDefault(); // throw exception
}
Another consideration, it is a possible to execute lambda expression in LiteDB without conversion by visitor?
In LiteDB v4, you can use expressions to make sure that the index of username is stored as lowercase, then you can perform a "lowercase-compare"
// Create index
entity.EnsureIndex(e => e.Username, "LOWER($.Username)");
...
// Find user
collection.Find(e => e.Username == username.ToLower);
If you dont want to use expressions, I guess that you could make sure the username is lowercase before saving in LiteDB or you can use an index less query (slower) by using collection.Where (not quite sure on that method though).
I have a need to verify that all the rows in a given set exist in the database and the current user has access to all the rows. I'd like to do this in a single query to the database, something like a .All() query but I can't quite come up with the right syntax (maybe it's not possible).
The iterative version of the code would look like:
bool canAccess;
foreach(var taskId in taskIds)
{
canAccess = await DataContext.WorkTasks.AnyAsync(wt => wt.DealerId == dealerId && wt.Id == taskId);
if(!canAccess) break;
}
I was thinking about something like:
var canAccess = await DataContext.WorkTasks.AllAsync(wt => wt.DealerId == dealerId && taskIds.Contains(wt.Id));
But I don't think that's what I want. Can this be done using LINQ?
Something like this:
var dbCount = await DataContext.WorkTasks.Where(wt => wt.DealerId == dealerId && taskIds.Contains(wt.Id)).Count();
Will send all your IDs to the server and count the matching rows.
To combine into a single query:
var q = DataContext.WorkTasks.Take(0); // setup q to right type
foreach (var taskId in taskIds)
q = q.Concat(DataContext.WorkTasks.Where(wt => wt.Id == taskId && wt.DealerId == dealerId));
var canAccess = (taskIds.Count() == q.Count());
I'm trying to select list of Users and for each User JobTitle in correct language depended of strLang selected by user.
Something like that:
IList<User> myData;
myData = Context.Users.Where(u => u.Location == strLocation)
.Include(u => u.JobTitles.Where(e => e.Language == strLang))
.ToList();
But it seems Include doesn't like Where clause
You can't conditionally include only a few entities of a related collection, so you should use projection to get the stuff you need:
IList<User> myData;
var temp = Context.Users.Where(u => u.Location == strLocation)
.Select(u => new
{
User = u;
Locations = u.JobTitles.Where(e => e.Language == strLang));
});
foreach(var t in temp)
{
User user = t.User;
user.Locations = t.Locations;
myData.Add(user);
}
You cannot do it by using the "Include" method since it only take naviation properties.
Disclaimer: I'm the owner of the project EF+ on github.
EF+ Query IncludeFilter allow you to easily filter related entities:
// using Z.EntityFramework.Plus; // Don't forget to include this.
IList<User> myData;
myData = Context.Users.Where(u => u.Location == strLocation)
.IncludeFilter(u => u.JobTitles.Where(e => e.Language == strLang))
.ToList();
You can find the project here
You can find the documentation here
Behind the code, IncludeFilter do exactly like Alexander answer by using a projection.
I am trying to look up record using if I have the key then use Find if not use Where
private ApplicationDbContext db = new ApplicationDbContext();
public bool DeactivatePrice(int priceId = 0, string sponsorUserName = "")
{
var prices = db.BeveragePrices;
// if we have an id then find
if (priceId != 0)
{
prices = prices.Find(priceId);
}
else
{
prices = prices.Where(b => b.UserCreated == sponsorUserName);
}
if (prices != null)
{
// do something
}
return true;
I get the following error for
prices = prices.Find(priceId);
Cannot convert app.Model.BeveragePrices from system.data.entity.dbset
I am copying the pattern from this answer but something must be different.
Seems you forgot to put a predicate inside the Find function call. Also you need to do ToList on the collection. The second option is a lot more efficient. The first one gets the whole collection before selection.
Another note commented by #Alla is that the find returns a single element. So I assume another declaration had been made for 'price' in the first option I state down here.
price = prices.ToList.Find(b => b.PriceId == priceId);
Or
prices = prices.Select(b => b.PriceId == priceId);
I assume the field name is PriceId.
In the following image you can see where i put the breakpoint and then debugged two step. You can also see that both assignments worked great they have the same count and are the same.
However if I do the following. Run the exact same call but only break on the third line directly then this happnes
set.QuestionSet.Questions should have count of 8 BEFORE the assigment, so it seems it's not properly assigned for some reason. I suspect this has something to do with how I fetch my data from DB.
Question and QuestionSet are normal POCOs and here is the code for the entire method.
public IEnumerable<QuestionSet> SearchAndFilterQuestionsAndSets(string searchString, int nrPerPage, int page, out int totalSearchCount)
{
searchString = searchString.ToLower();
List<QuestionSet> finalList = new List<QuestionSet>();
var result = ActiveContext.QuestionSets
.Select(x => new
{
QuestionSet = x,
Questions = x.Questions.Where(
y =>
y.Description.ToLower().Contains(searchString)
).OrderBy(
z => z.Description
)
})
.ToList();
foreach (var set in result)
{
//If our search matched the set itself we load all questions
if (set.QuestionSet.Name.ToLower().Contains(searchString))
{
//we dont bring empty sets
if (set.QuestionSet.Questions.Count() > 0)
{
set.QuestionSet.Questions = set.QuestionSet.Questions.ToList<Question>().OrderBy(x => x.Description).ToList<Question>();
finalList.Add(set.QuestionSet);
}
}
//We had one or more questions matching the search term
else if (set.Questions.Count() > 0)
{
var b = set.Questions.ToList<Question>();
set.QuestionSet.Questions = set.Questions.ToList<Question>();
finalList.Add(set.QuestionSet);
}
}
totalSearchCount = finalList.Count();
return finalList.Skip((page - 1) * nrPerPage).Take(nrPerPage);
}
UPDATE
If I do this instead in the failing else if
var a = new QuestionSet();
a.Id = set.QuestionSet.Id;
a.Name = set.QuestionSet.Name;
a.Questions = set.Questions.ToList<Question>();
finalList.Add(a);
Then it works, so the problem lies within the anonymous object, but why does it work when i step through with debugger and not otherwise?? call me puzzled.
Could be something to do with Late binding of anonymous types