Is there any way to use DataContext to execute some explicit SQL and return the auto-increment primary key value of the inserted row without using ExecuteMethodCall? All I want to do is insert some data into a table and get back the newly created primary key but without using LINQ (I use explicit SQL in my queries, just using LINQ to model the data).
Cheers
EDIT: Basically, I want to do this:
public int CreateSomething(Something somethingToCreate)
{
string query = "MyFunkyQuery";
this.ExecuteCommand(query);
// return back the ID of the inserted value here!
}
SOLUTION
This one took a while. You have to pass a reference for the OUTPUT parameter in your sproc in your parameter list of the calling function like so:
[Parameter(Name = "InsertedContractID", DbType = "Int")] ref System.Nullable<int> insertedContractID
Then you have to do
insertedContractID = ((System.Nullable<int>)(result.GetParameterValue(16)));
once you've called it. Then you can use this outside of it:
public int? CreateContract(Contract contractToCreate)
{
System.Nullable<int> insertedContractID = null; ref insertedContractID);
return insertedContractID;
}
Take heavy note of GetParameterValue(16). It's indexed to whichever parameter it is in your parameter list (this isn't the full code, by the way).
You can use something like this:
int newID = myDataContext.ExecuteQuery<int>(
"INSERT INTO MyTable (Col1, Col2) VALUES ({0}, {1});
SELECT Convert(Int, ##IDENTITY)",
val1, val2).First();
The key is in converting ##IDENTITY in type int, like Ben sugested.
If you insist on using raw sql queries, then why not just use sprocs for your inserts? You could get the identity returned through an output parameters.
I'm not the greatest at SQL, but I broke out LinqPad and came up with this. It's a big hack in my opinion, but it works ... kinda.
DataContext.ExecuteQuery<T>() returns an IEnumerable<T> where T is a mapped linq entity. The extra select I added will only populate the YourPrimaryKey property.
public int CreateSomething(Something somethingToCreate)
{
// sub out your versions of YourLinqEntity & YourPrimaryKey
string query = "MyFunkyQuery" + "select Convert(Int, SCOPE_IDENTITY()) as [YourPrimaryKey]";
var result = this.ExecuteQuery<YourLinqEntity>(query);
return result.First().YourPrimaryKey;
}
You'll need to modify your insert statement to include a SELECT ##Identity (SQL Server) or similar at the end.
Related
So am using AspNetCore 1.0 with EFCore 1.0, both latest releases as far as I am aware.
Executing a query to delete an object using the FromSql method on a DbSet throws an exception. Both the code and exception are below.
public void DeleteColumn(int p_ColumnID)
{
int temp = p_ColumnID;
string query = "DELETE FROM Columns WHERE ID = {0}";
var columnsList = m_context.Columns.FromSql(query, p_ColumnID).ToList();
foreach (Columns c in columnsList)
{
m_context.Columns.Remove(c);
}
m_context.SaveChanges();
}
After executing the FromSql call, I get the following exception
An exception of type 'System.NotSupportedException' occurred in Remotion.Linq.dll but was not handled in user code
Additional information: Could not parse expression 'value(Microsoft.EntityFrameworkCore.Query.Internal.EntityQueryable`1[ASPNET5_Scrum_Tool.Models.Columns]).FromSql("DELETE FROM Columns WHERE ID = {0}", __p_0)': This overload of the method 'Microsoft.EntityFrameworkCore.RelationalQueryableExtensions.FromSql' is currently not supported.
I have no clue how to fix this error and from Googling I have come across no similar problems.
I am also wondering, if the query/code was successful it would return an 'IQueryable object. Would that solely contain the results of the query, in this case the specific Column object to delete?
FromSql is intended to allow you to compose a custom SQL SELECT statement that will return entities. Using it with a DELETE statement is not appropriate here, since your goal is to load the records you want to delete and then delete them using the default Entity Framework mechanism. A Delete statement generally does not return the records deleted (though there are ways to accomplish that). Even if they did, the records will already be deleted and so you won't want to iterate over them and do a Remove on them.
The most straightforward way to do what you want might be to use the RemoveRange method in combination with a Where query.
public void DeleteColumn(int p_ColumnID)
{
m_context.Columns.RemoveRange(m_context.Columns.Where(x => x.ID == p_ColumnID))
m_context.SaveChanges();
}
Alternately, if you want to load your entities and iterate manually through them to
public void DeleteColumn(int p_ColumnID)
{
columnList = m_context.Columns.Where(x => x.ID == p_ColumnID);
foreach (Columns c in columnsList)
{
m_context.Columns.Remove(c);
}
m_context.SaveChanges();
}
If you really want to issue the Delete statement manually, as suggested by Mike Brind, use an ExecuteSqlCommand method similar to:
public void DeleteColumn(int p_ColumnID)
{
string sqlStatement = "DELETE FROM Columns WHERE ID = {0}";
m_context.Database.ExecuteSqlCommand(sqlStatement, p_ColumnID);
}
I had the same exception in a case where I did not use delete statement. Turns out I was using the In-Memory Database. Since it is not a real database you can't use FromSQL.
I have the following (simplified) Entity SQL query:
SELECT VALUE a
FROM Customers AS a
WHERE a.Status NOT IN { 2, 3 }
The Status property is an enumeration type, call it CustomerStatus. The enumeration is defined in the EDMX file.
As it is, this query doesn't work, throwing an exception to the effect that CustomerStatus is incompatible with Int32 (its underlying type is int). However, I couldn't find a way to define a list of CustomerStatus values for the IN {} clause, no matter what namespace I prefixed to the enumeration name. For example,
SELECT VALUE a
FROM Customers AS a
WHERE a.Status NOT IN { MyModelEntities.CustomerStatus.Reject, MyModelEntities.CustomerStatus.Accept }
did not work, throwing an exception saying it could not find MyModelEntities.CustomerStatus in the container, or some such.
Eventually I resorted to casting the Status to int, such as
SELECT VALUE a
FROM Customers AS a
WHERE CAST(a.Status AS System.Int32) NOT IN { 2, 3 }
but I was hoping for a more elegant solution.
Oooh, you are writing Entity SQL directly. I see... Any reason you aren't using DbSet instead of writing Entity SQL by hand? Could always do
var statuses = new [] { Status.A, Status.B };
var query = context.SomeTable.Where(a => !statuses.Contains(a.Status)).ToList();
With the code below I am having an issue where not all the columns are return data in the data.results array. For example if col4 is null in the database for row 1 then data.results[0] does not contain an element for col4, but row 2 has a value then data.results[1] will contain the value for col4. I would like each return item in the array to contain all items with the database value or null. If null can't be returned then an empty string would do.
var query = new breeze.EntityQuery()
.from('mytable')
.where('col1', 'substringof', '2')
.select('col1,col2,col3,col4')
.orderBy('col1')
.take(200);
return _manager
.executeQuery(query)
.then(function (data) {
return data.results;
})
.fail(queryFailed);
}
By default breeze does not serialize null values in its JSON results. This was a deliberate choice to reduce the breeze payload over the wire. And.. this is not typically an issue with queries that return "entities". i.e. data for which breeze metadata exists. Because the properties are already defined on such entities.
But if you are returning an anonymous result as you are, then this can be a problem. You can obviously work around it because you know the properties that you are requesting and can update them after the query if they are not in the result.
But you can also change breeze's default configuration to accommodate this via the "BreezeConfig" class.
BreezeConfig enables customization of components supporting Breeze-related operations in the Web API. BreezeConfig defines default behaviors; you can substitute your own behaviors by deriving from it and overriding its virtual methods. Breeze.NET will discover your subclass among the assemblies referenced by your project and use it instead of BreezeConfig.
To use BreezeConfig to configure the Json.Net serializer with specific settings. You can replace those settings by writing a subclass of BreezeConfig that overrides the 'CreateJsonSerializerSettings' method as shown in this example:
public class CustomBreezeConfig : Breeze.WebApi.BreezeConfig {
protected override JsonSerializerSettings CreateJsonSerializerSettings() {
var baseSettings = base.CreateJsonSerializerSettings();
baseSettings.NullValueHandling = NullValueHandling.Include;
return baseSettings;
}
Hope this helps.
With a plain connection to SQL Server, you can specify what columns to return in a simple SELECT statement.
With EF:
Dim who = context.Doctors.Find(3) ' Primary key is an integer
The above returns all data that entity has... BUT... I would only like to do what you can with SQL and get only what I need.
Doing this:
Dim who= (From d In contect.Doctors
Where d.Regeneration = 3
Select New Doctor With {.Actor = d.Actor}).Single
Gives me this error:
The entity or complex type XXXXX cannot be constructed in a LINQ to Entities query.
So... How do I return only selected data from only one entity?
Basically, I'm not sure why, but Linq can't create the complex type. It would work if you were creating a anonymous type like (sorry c# code)
var who = (from x in contect.Doctors
where x.Regeneration == 3
select new { Actor = x.Actor }).Single();
you can then go
var doctor = new Doctor() {
Actor = who.Actor
};
but it can't build it as a strongly typed or complex type like you're trying to do with
var who = (from x in contect.Doctors
where x.Regeneration == 3
select new Doctor { Actor = x.Actor }).Single();
also you may want to be careful with the use of single, if there is no doctor with the regeneration number or there are more than one it will throw a exception, singleordefault is safer but it will throw a exception if there is more than one match. First or Firstordefault are much better options First will throw a exception only if none exist and Firstordefault can handle pretty much anything
The best way to do this is by setting the wanted properties in ViewModel "or DTO if you're dealing with upper levels"
Then as your example the ViewModel will be:
public class DoctorViewModel{
public string Actor {get;set;}
// You can add as many properties as you want
}
then the query will be:
var who = (From d In contect.Doctors
Where d.Regeneration = 3
Select New DoctorViewModel {Actor = d.Actor}).Single();
Sorry i wrote the code with C# but i think the idea is clear :)
You can just simply do this:
Dim who= (From d In contect.Doctors
Where d.Regeneration = 3
Select d.Actor).Single
Try this
Dim who = contect.Doctors.SingleOrDefault(Function(d) d.Regeneration = 3).Actor
Could you please check my code? Why can't I get any values back when I use Linq to Sql?
BHS_TimeSheet is my database table in which have some records.
Model.TimeSheet is a class I create in the model.
Private db As DataFactoryDataContext
Public Sub New()
db = New DataFactoryDataContext
End Sub
Public Sub New(ByVal repository As DataFactoryDataContext)
db = repository
End Sub
Public Function GetTimeSheetByProject(ByVal wbs1 As String, ByVal wbs2 As String, ByVal wbs3 As String) _
As List(Of Model.TimeSheet) Implements ITimeSheetRepository.GetTimeSheetByProject
Return (From ts In db.BHS_TimeSheets _
Where ts.WBS1.Equals(wbs1) And ts.WBS2.Equals(wbs2) And ts.WBS3.Equals(wbs3) _
Select New Model.TimeSheet(ts.TSBatchNo, ts.Employee, ts.TransDate, ts.WBS1, ts.WBS2, ts.WBS3, ts.LaborCode, _
ts.RegHrs, ts.OvtHrs, ts.SpecialOvtHrs, ts.TransComment, ts.Status, ts.AuthorizedBy, _
ts.RejectReason, ts.ModDate)).ToList
End Function
Your Linq-to-SQL statement
(From ts In db.BHS_TimeSheets
Where ts.WBS1.Equals(wbs1)
And ts.WBS2.Equals(wbs2)
And ts.WBS3.Equals(wbs3) _
basically corresponds to this SQL query:
SELECT * FROM dbo.BHS_TimeSheets
WHERE WBS1 = (value for wbs1)
AND WBS2 = (value for wbs2)
AND WBS3 = (value for wbs3)
Does that SQL query return any values, if you call it with in SQL Server Management Studio using the same parameters for wbs1, wbs2, wbs3 as you do in your Linq-to-SQL code??
Update: okay, so the SQL query does return results - next step: approach the Linq-to-SQL stuff step by step. First, try this - do you get any results??
Dim basicQueryResults = (From ts In db.BHS_TimeSheets
Where ts.WBS1.Equals(wbs1)
And ts.WBS2.Equals(wbs2)
And ts.WBS3.Equals(wbs3)
).ToList();
Does your resulting list of items have a .Count > 0 or not??
If not: there must be something wrong with your Linq-to-SQL model then. Have you changed your database and not updated the DBML file?? Can you drop the DBML file and do it again - does it work now? Or do you still have the same results??