Version 11.4
All of my Sqlite table fields are set to NOT NULL.
I have tried the following in the table creation command ..
t.column(miny, defaultValue: nil)
but the fields are still all defined 'NOT NULL'
How do I set a field to accept a NULL value?
Doh! - found the answer looking through the testing scripts in github - then noticed the comment in the docs.
Need to make the types optional using a '?' - as with the last 4 Double fields in this example ..
let title = Expression<String>("title")
let descr = Expression<String>("descr")
let miny = Expression<Double?>("miny")
let minx = Expression<Double?>("minx")
let maxy = Expression<Double?>("maxy")
let maxx = Expression<Double?>("maxx")
Have you tried the following syntax:
t.column(miny)
From the SQLite documentation:
The default value of each column is NULL
So you should not have to specify anything extra in a column definition in order for it to be nullable, because the default value is already null.
Related
I have seen some questions related to this Exception here but none made me understand the root cause of the problem. So here we have one more...
var testquery =
((from le in context.LoanEMIs.Include("LoanPmnt")
join lp in context.LoanPmnts on le.Id equals lp.LoanEMIId
where lp.PmntDtTm < date && lp.IsPaid == false
&& le.IsActive == true && lp.Amount > 0
select new ObjGetAllPendingPmntDetails
{
Id = lp.Id,
Table = "LoanEMI",
loanEMIId = lp.LoanEMIId,
Name = le.AcHead,
Ref = SqlFunctions.StringConvert((double)le.FreqId),
PmntDtTm = lp.PmntDtTm,
Amount = lp.Amount,
IsDiscard = lp.IsDiscarded,
DiscardRemarks = lp.DiscardRemarks
}).DefaultIfEmpty(ObjNull));
List<ObjGetAllPendingPmntDetails> test = testquery.ToList();
This query gives the following Exception Message -
Unable to create a constant value of type CashVitae.ObjGetAllPendingPmntDetails. Only primitive types or enumeration types are supported in this context.
I got this Exception after I added the SQL function statement to convert le.FreqId which is a byte to a string as ToString() is not recognized in the LINQ Expression Store.
ObjGetAllPendingPmntDetails is a partial class in my model which is added as it is used too many times in the code to bind data to tables.
It has both IDs as long, 'Amount' as decimal, PmntDtTm as Datetime,IsDiscard as bool and remaining all are string including 'Ref'.
I get no results as currently no data satisfies the condition. While trying to handle null, I added DefaultIfEmpty(ObjNull) and ObjNull has all properties initialized as follows.
ObjGetAllPendingPmntDetails ObjNull = new ObjGetAllPendingPmntDetails()
{ Id = 0, Table = "-", loanEMIId = 0, Name = "-", Ref = "-",
PmntDtTm = Convert.ToDateTime("01-01-1900"),
Amount = 0, IsDiscard = false, DiscardRemarks = "" };
I need this query to work fine as it has Union() called on it with 5 other queries. All returning the same ObjGetAllPendingPmntDetails columns. But there is some problem as this query has no data satisfying the conditions and the Exception Shared Above.
Any suggestions are appreciated as I am unable to understand the root cause of the problem.
#AndrewCoonce is right, the .DefaultIfEmpty(ObjNull) is the culprit here. Entity Framework turns DefaultIfEmpty into something like...
CASE WHEN ([Project1].[C1] IS NULL) THEN #param ELSE [Project1].[Value] END AS [C1]
...but there's no way to coerce an instance of ObjGetAllPendingPmntDetails into something that can take the place of #param, so you get an exception.
If you move the DefaultIfEmpty call to after the ToList it should work correctly (although you'll need to call ToList again after that if you really want a concrete list instance).
please guide, i am able to work with Dynamic Group by , but when selecting non agrigated fields , i get the following error
No property or field 'name' exists in type 'IGrouping`2'
var result311 = (IQueryable)gle1.temptable.Where(a => a.IsAllowed == false && a.Code == "r01");
var result = result311.GroupBy("new (name, FirstAmountOriginal, SecondAccounting)", "it")
.Select("new (it.name,Sum(FirstAmountOriginal) as FirstAmountOriginalx, Sum(SecondAccounting) as SecondAccountingx)");
Please guide
Firstly, you should not group by the fields you want to aggregate and secondly, the grouping creates a grouping Key consisting of the fields you group by (in this case one), so you must address this key afterwards:
var result = result311.GroupBy("new(name)", "it")
.Select(#"new (it.Key.name,
Sum(FirstAmountOriginal) as FirstAmountOriginalx,
Sum(SecondAccounting) as SecondAccountingx)");
When setting a Lookup value in CRM everything works fine if you don't want to change anything, or if you want to set it to a new value. However, when you want to UNSET the current value, the way to do so is unclear.
For example,
house.new_associatepastorid = new HLCImport.CrmSdk.Lookup();
house.new_associatepastorid.type = EntityName.contact.ToString();
house.new_associatepastorid.value = Guid.Empty;
Does not work.
Setting the IsNull and IsNullSpecified properties is absolutely fine. For simpler code, all of the standard types has a static member named Null. So in this case you could have used Lookup.Null.
I found the answer in the SDK. You have to set the isnull value = true, as well as set the isnullspecified = true. You also need to not set the type or the value fields. So the code would be:
house.new_associatepastorid = new HLCImport.CrmSdk.Lookup();
house.new_associatepastorid.IsNullSpecified = true;
house.new_associatepastorid.IsNull = true;
I want to query a datatable (dt) and load a 2nd dt with the resultant collection of datarows. Fine - we have the CopyToDataTable() extn mthd for exactly that purpose. However it is constrained to enumerate only over DataRows, which means that I cannot return anything else e.g. a collection of anonymous types. So - how can I modify the values in the datarows?
Eg I have a dt with 3 columns: MyPK, VARCHAR01, VARCHAR02.
Foreach row, if VARCHAR01 or VARCHAR02 has the value "" (i.e. String.Empty) I want to replace that with NULL (which the underlying type allows).
I would do this as follows:
var MyCleanedDatarows =
from o in ds.Tables["dt"].AsEnumerable()
select new {
MyPK = o.Field<string>("MyPK"),
VARCHAR01 = (o.Field<string?>("VARCHAR01") == "" ? NULL : o.Field<string?>("VARCHAR01") ),
VARCHAR02 = (o.Field<string?>("VARCHAR02") == "" ? NULL : o.Field<string?>("VARCHAR02") )
};
...but then I cant use CopyToDataTable() to get back to a dt. I'm thinking I need to modify the datarows before invoking select operator, but I dont know how to achieve that. Any help/thoughts would be v.greatfully recieved.
Thanks in advance,
Tamim.
Take a look at this approach, in MSDN documentation.
http://msdn.microsoft.com/en-us/library/bb669096.aspx
I have the following LINQ query:
DataClassesDataContext dc = new DataClassesDataContext();
var query = from contact in dc.Contacts
select new
{
ContactId = contact.ContactId,
LastName = contact.LastName,
FirstName = contact.FirstName,
Addresses = contact.Addresses,
Phones = contact.Phones,
DOB = contact.BirthDate,
LastNote = contact.Notes.Max(n => n.Created), //this line causes the error
Status = contact.ContactStatus.ContactStatusName,
EmailAddress = contact.Emails
};
The line where I get the maximum created date for the notes collection causes the following exception to be thrown:
Exception: The null value cannot be assigned to a
member with type System.DateTime which
is a non-nullable value type.
How do I write the query to allow null values into the LastNote field? The DOB field is defined as DateTime? and has not problem handling nulls.
Think I figured it out.
If I cast the maximum note value to a nullable DateTime it seems to eliminate the exception. The following change worked for me:
LastNote = (Nullable<DateTime>)contact.Notes.Max(n => n.Created)
As others have pointed out, it can also be written using the shorthand notation for a nullable DateTime as follows:
LastNote = (DateTime?) contact.Notes.Max(n => n.Created)
Rewrite that line as:
LastNote = (DateTime?) contact.Notes.Max(n => n.Created),
LastNote = contact.Notes.Max(n => (DateTime?)n.Created)
Couldn't find this on the net so i hope this helps others.
In VB is something like:
LastNote = CType(contact.Notes.Max(n => n.Created), Global.System.Nullable(Of Date))
I think...
You could do that, or you could alter your database schema so that the column 'Created' does not allow nulls.
The scenario is arising because one of the rows comes back with a null value for Created.
If the db didn't allow nulls, the scenario would never occur.