i have written the following code
var resumeedit=(from t in db.Resumes where t.User.UserID==theUserID && t.ResumeID==theResumeID select t).Select(t=> new EditResumes
{
Iswizard=t.isWizard,
Resumeid=t.ResumeID.ToString()
}).First();
EditResumes ed = (EditResumes)resumeedit;
and it is giving error LINQ to Entities does not recognize the method 'System.String ToString()' method, and this method cannot be translated into a store expression.
this line
Resumeid=t.ResumeID.ToString()
what happens when you make it
Resumeid=t.ResumeID
?
or simple do:
select new { t.ResumeID, t.isWizard }
Like the message says, L2E doesn't do .ToString(). So use .AsEnumerable() to bring it into L2O:
var resumeedit= (from t in db.Resumes
where t.User.UserID==theUserID && t.ResumeID==theResumeID
select t)
.AsEnumerable()
.Select(t=> new EditResumes
{
Iswizard=t.isWizard,
Resumeid=t.ResumeID.ToString()
}).First();
This cast should be unnecessary:
EditResumes ed = (EditResumes)resumeedit;
Related
I completely understand that this is because LINQ query requires the whole expression to be translated to a server , and therefore I cant call an outside method in it. but as I have looked at other answers there is not relative solution to this. the only approach that I thought about is to loop through all the items in the model and than passing them to the query one by one but even though this approach would not help so I am seeking help in here for anyone to help me to figure out how to call a method or a way of calling a method appendstr that initializes a.PostedDate before checking its actual equivalent value in the giving LINQ Query.
[HttpGet]
public ActionResult SearchResult(int? page, string searchTitle = null, string searchLocation = null, string last24 = "")
{
ViewBag.searchTitle = searchTitle;
ViewBag.searchLocation = searchLocation;
ViewBag.page = page;
ViewBag.last24 = last24;
setUpApi(searchTitle, searchLocation);
var result = new List<AllJobModel>().AsQueryable();
if (!string.IsNullOrEmpty(ViewBag.searchTitle) || !string.IsNullOrEmpty(ViewBag.searchTitle) || !string.IsNullOrEmpty(ViewBag.last24))
{
setUpApi(searchTitle, searchLocation);
DateTime now = DateTime.Now;
result = db.AllJobModel.Where(a => a.JobTitle.Contains(searchTitle) && a.locationName.Contains(searchLocation) &&
appendstr(a.PostedDate).Equals(now.AddHours(-24).ToString("MM-dd-yyyy")));
}
else
{
result = from app in db.AllJobModel select app;
}
return View(result.ToList().ToPagedList(page ?? 1, 5));
}
The second method that gets called in the LINQ Query
public string appendstr(string str)
{
var x = str.Split(' ');
return 01 + "-" + x[1] + "-" + x[2];
}
I think you already understand that the .NET code you write in the Where clause is actually an expression that is parsed and converted to SQL. So if you have a funky string manipulation method, you can't use it directly.
The brute force option, as you seem to already understand, it to materialize the query first and then run the C# code over the results. You can do this with ToList() or AsEnumerable().
result = db.AllJobModel
.Where
(
a => a.JobTitle.Contains(searchTitle)
&& a.LocationName.Contains(searchLocation)
)
.AsEnumerable()
.Where
(
a => appendstr(a.PostedDate).Equals(now.AddHours(-24).ToString("MM-dd-yyyy")))
);
However in your specific case you can try a trick. You are attempting a date comparison, which SQL is perfectly capable of doing... you just need to convert that funky PostedDate to a SQL DateTime so that you can compare it directly. The gimmick for that is to use SqlFunctions.DateAdd to add null interval (e.g. 0 days). This implicitly converts the string to DateTime, where you can now query on the SQL side:
var targetDate = DateTime.Now.AddHours(-24);
result = db.AllJobModel
.Where
(
a => a.JobTitle.Contains(searchTitle)
&& a.LocationName.Contains(searchLocation)
&& SqlFunctions.DateAdd("DAY", 0, a.PostedDate) == targetDate
);
Credit goes to this post for the workaround.
var query = from c in context.Albums
where c.AlbumID in albumIds
select c.Albumname;
Here albumIds is IENUM<> of some custom type(in my case its an Entity)
When I do the above query I get an error
Operator == cannot be applied to type int and IEnumerable
This error is acceptable but how do I overcome this
Turn it around slightly - you want to check whether your enumerable of album ids contains the id of an album you have just iterated to in your linq. So something like this ...
albumIds = {1,2,13,25,277,567};
var query = context.Albums.Where(x=> albumIds.Contains(x.ID));
(Sorry, writing example code without a tool in front of me so forgive any obvious mistakes. Hopefully you can get the idea from this though).
var albumIds= new string[] { "900", "801", "802", "803","906" };
var lstData = context.tbl.Where(
x => (x.TimeCreated >= yesterday && x.TimeCreated < today) &&
albumIds.Contains(x.TransactionSetId)
).Select(x => x.X12_Interchange).ToList();
hi guys i am stuck converting below sql to LINQ query.
all i want is to have maximum number from list of (FA-00001 ,FA-00059)
SELECT MAX(CAST(SUBSTRING(ReferenceId, PATINDEX('%-%', ReferenceId) + 1, LEN(ReferenceId) - PATINDEX('%-%', ReferenceId)) AS int)) AS MaxReferenceId FROM [ClientRC].[dbo].[EHO_Action]
is this possible to convert to LINQ? thanks
An alternative approach using anonymous projection:
var y = (from record in
(from record in db.ClientRC
select new
{
Group = "x",
ReferenceNumber = Convert.ToInt32(record.ReferenceId.Split('-')[1])
})
group record by new { record.Group } into g
select new
{
MaxReferenceId = g.Max(p => p.ReferenceNumber)
});
http://msdn.microsoft.com/en-us/library/bb386972.aspx
var myvar = (from v in db.object where v!=null select v.id).Max();
MSDN has lots of examples for stuff like this.
Or, you can execute queries directly against a datacontext if you're using entity framework. Just make sure if you're doing anything with parameters you're parameterizing the query and not taking user input directly into it.
http://msdn.microsoft.com/en-us/library/ee358769.aspx
Try this..
var list = DBContext.EHO_Action
.Where(x => x.YourListColumn != null)
.Select(x => x.YourListColumn).ToList(); // Take the list (FA-00001 ,FA-00059) from db to a list
var maxNo = list.Max(x => Convert.ToInt32(x.Split('-')[1]));
Please change the context and column names according to your Linq context.
If you want to use sql you can do it this way..
var list = DBContext.ExecuteQuery<string>("select yourreqrdcolumn from [ClientRC].[dbo].[EHO_Action]");
I have a label to show BookName. I get it from table which name tblBooks. I don't know how to show Book Name into the label.
var query = from b in dc.tblBooks.Where(b=>b.BookID == 'B01') select b;
Can you help me know.
Your query as written will return a collection of books—IQueryable<Book>. If you're sure there will only be one result in this query, you can call SingleOrDefault, which will execute the query immediately and give you the actual book.
var Book = dc.tblBooks.Where(b => b.BookID == 'B01').SingleOrDefault();
if (Book != null)
myLabel.Text = Book.BookName;
Or you can simply say:
var Book = dc.tblBooks.SingleOrDefault(b => b.BookID == 'B01');
Which does the same thing.
If you're 110% sure there will always be a result, and you don't want to check for null, then you can use Single, which will do the same thing, except throw an exception if no results are found, where SingleOrDefault simple returns null.
var Book = dc.tblBooks.Single(b=>b.BookID == 'B01');
myLabel.Text = Book.BookName;
Try:
label.Text = query.FirstOrDefault().BookName;
Ok now for the juicy stuff. All attempts failed to save my string so far.
Here is the code for saving it in sqllite in firefox extension:
var file = Components.classes["#mozilla.org/file/directory_service;1"]
.getService(Components.interfaces.nsIProperties)
.get("ProfD", Components.interfaces.nsIFile);
file.append("my_db_file_name.sqlite");
var storageService = Components.classes["#mozilla.org/storage/service;1"]
.getService(Components.interfaces.mozIStorageService);
var mDBConn = storageService.openDatabase(file);
mDBConn.execute("CREATE TABLE IF NOT EXISTS log_det (id INTEGER PRIMARY KEY AUTOINCREMENT, acc STRING)");
mDBConn.execute("INSERT INTO log_det (acc) VALUES(" + window['gluistr']+ ")");
mDBConn.drop();
And the code for retrieving the value:
var file = Components.classes["#mozilla.org/file/directory_service;1"]
.getService(Components.interfaces.nsIProperties)
.get("ProfD", Components.interfaces.nsIFile);
file.append("my_db_file_name.sqlite");
var storageService = Components.classes["#mozilla.org/storage/service;1"]
.getService(Components.interfaces.mozIStorageService);
var mDBConn = storageService.openDatabase(file);
var res = mDBConn.execute("SELECT * FROM log_det");
mDBConn.drop();
Is not working. Anybody knows why? Is "execute" ok or do I need "createStatement" or "executeSimpleSQL". I am confused.
Use executeSimpleSQL.
openDatabase returns a mozIStorageConnection instance, which does not have any method named execute. You can use executeSimpleSQL any time you want to execute a SQL statement without bound parameters (which is what you're doing).
You were probably thinking of mozIStorageStatement's execute method. executeSimpleSQL is not sufficient when bound parameters are necessary. Instead, you need to create a statement, bind any parameters, and then execute it:
var statement = mDBConn.createStatement(
"SELECT * FROM log_det WHERE column_name = :parameter");
statement.bindStringParameter(0, "value");
statement.execute();
statement.reset();
Also note that mozIStorageConnection does not have any method named drop. Maybe you meant to write mDBConn.close()?
All of this is covered here:
https://developer.mozilla.org/en/storage