Now that NHibernate 5 is out, I was wondering what's the recommended approach to load dates as local dates when they're persisted as datetime2 in a SQL Server 2016 database. Until now, dates were interpreted as local (so, the properties ended up with the correct values), but now, the behavior has changed and I'm unable to use the LocalDateTime.
Unfortunately, my donmain's behavior relies in getting those dates automatically loaded as local dates...
Any pointers on how to solve this?
Thanks,
Luis
Since I didn't found a way to disable this behavior, I've ended up creating a new type that will simply adjust the format of the data (considering always that it was saved in local format):
public class LocalDateTimeTypeNoThrow : LocalDateTimeType {
public LocalDateTimeTypeNoThrow() {
}
public LocalDateTimeTypeNoThrow(DateTimeSqlType sqlType) : base(sqlType) {
}
public override string Name => "LocalDateTimeNoThrow";
public override void Set(DbCommand st, object value, int index, ISessionImplementor session) {
var dateValue = (DateTime) value;
//removed throwing from here
st.Parameters[index].Value = AdjustDateTime(dateValue);
}
}
If there's a better way, please let me know.
Luis
Related
We have a field in our SQL Server database table which is autogenerated by SQL Server, the field is called CreatedTime.
We have mapped the whole database table to our datamodel in Entity Framework, thus also the field CreatedTime.
When we insert a new row in the database, via Entity Framework, we thus do not provide any value for CreatedTime.
This causes the insert to fail with the error:
SqlDateTime overflow. Must be between 1/1/1753 12:00:00 AM and 12/31/9999 11:59:59 PM
So the question is: Is there is a way to to exclude a particular field in the Entity datamodel in the Entity Framework insert statement? So that we will not get the above error?
We would like to keep the field CreatedTime in the Entity model, because we might want to access it later.
If using Fluent API:
using System.ComponentModel.DataAnnotations.Schema;
this.Property(t => t.CreatedTime)
.HasDatabaseGeneratedOption(DatabaseGeneratedOption.Computed);
If using Annotations
[DatabaseGenerated(DatabaseGeneratedOption.Computed)]
public System.DateTime CreatedTime { get; set; }
I found a simple solution to the problem on this thread:
http://social.msdn.microsoft.com/Forums/en-US/adodotnetentityframework/thread/7db14342-b259-4973-ac09-93e183ae48bb
There Fernando Soto writes:
"If you go to the EDM designer click on the field in the table that is auto-generated by the database, right click on it and select Properties and
look at the properties windows click on StoreGeneratedPattern and set its value to Computed, I believe it will give you what you are looking for."
The above solution was super quick and easy and it seems to work.
Also thank you for your contributions guys, but the above solution seems to do the job.
Try to use NotMapped attribute on this property
http://msdn.microsoft.com/en-us/library/system.componentmodel.dataannotations.schema.notmappedattribute.aspx
there are two things you can do:
If you have access to the database, check if the field has a default value. If it doesn't you can set it to GETDATE(), and the field should be set correctly, and you don't have to add/update it through Entity Framework.
If you don't have access to the database, or don't want to make any changes there, you can alter the behavior of the Entity Data Model to automatically set the date. Simply extend your ObjectContext model.
public partial class MyEntities
{
public override int SaveChanges()
{
var entityChangeSet = ChangeTracker.Entries<SomeEntity>();
if (entityChangeSet != null)
{
foreach (DbEntityEntry<SomeEntity> entry in entityChangeSet )
{
switch (entry.State)
{
case EntityState.Modified:
entry.Entity.LastModifiedDate = DateTime.UtcNow;
break;
case EntityState.Added:
entry.Entity.CreatedDate = DateTime.UtcNow;
break;
}
}
}
return base.SaveChanges();
}
}
This way you don't have to add any information for those fields when you add or update an item, the model will do it for you. If you have multiple entities which need this behavior, you can create an interface and make the Entity classes inherit that:
public interface IHaveCreatedDate {
DateTime CreatedDate { get; set; }
}
public partial class MyEntity : IHaveCreatedDate {
//MyEntity already implements this!
}
Then all you need to do is change the call to the ChangeTracker:
var entityChangeSet = ChangeTracker.Entries<IHaveCreatedDate>();
Is CreatedTime nullable?
One possible workaround - if CreatedTime is NOT nullable:
DateTime sqlServerMinDateTime = new DateTime(1753, 1, 1, 12, 0, 1, 0);
if(myEntity.CreatedTime < sqlServerMinDateTime)
{
myEntity.CreatedTime = sqlServerMinDateTime;
}
// do insert here
// ....
One possible workaround - if CreatedTime is nullable:
DateTime sqlServerMinDateTime = new DateTime(1753, 1, 1, 12, 0, 1, 0);
if(myEntity.CreatedTime < sqlServerMinDateTime)
{
myEntity.CreatedTime = null;
}
// do insert here
// ....
I am quite new to ASP .NET core, so please help. I would like to avoid database round trip for ASP .NET core application. I have functionality to dynamically add columns in datagrid. Columns settings (visibility, enable, width, caption) are stored in DB.
So I would like to store List<,PersonColumns> on server only for actual session. But I am not able to do this. I already use JsonConvert methods to serialize and deserialize objects to/from session. This works for List<,Int32> or objects with simple properties, but not for complex object with nested properties.
My object I want to store to session looks like this:
[Serializable]
public class PersonColumns
{
public Int64 PersonId { get; set; }
List<ViewPersonColumns> PersonCols { get; set; }
public PersonColumns(Int64 personId)
{
this.PersonId = personId;
}
public void LoadPersonColumns(dbContext dbContext)
{
LoadPersonColumns(dbContext, null);
}
public void LoadPersonColumns(dbContext dbContext, string code)
{
PersonCols = ViewPersonColumns.GetPersonColumns(dbContext, code, PersonId);
}
public static List<ViewPersonColumns> GetFormViewColumns(SatisDbContext dbContext, string code, Int64 formId, string viewName, Int64 personId)
{
var columns = ViewPersonColumns.GetPersonColumns(dbContext, code, personId);
return columns.Where(p => p.FormId == formId && p.ObjectName == viewName).ToList();
}
}
I would like to ask also if my approach is not bad to save the list of 600 records to session? Is it better to access DB and load columns each time user wants to display the grid?
Any advice appreciated
Thanks
EDIT: I have tested to store in session List<,ViewPersonColumns> and it is correctly saved. When I save object where the List<,ViewPersonColumns> is property, then only built-in types are saved, List property is null.
The object I want to save in session
[Serializable]
public class UserManagement
{
public String PersonUserName { get; set; }
public Int64 PersonId { get; set; }
public List<ViewPersonColumns> PersonColumns { get; set; } //not saved to session??
public UserManagement() { }
public UserManagement(DbContext dbContext, string userName)
{
var person = dbContext.Person.Single(p => p.UserName == userName);
PersonUserName = person.UserName;
PersonId = person.Id;
}
/*public void PrepareUserData(DbContext dbContext)
{
LoadPersonColumns(dbContext);
}*/
public void LoadPersonColumns(DbContext dbContext)
{
LoadPersonColumns(dbContext, null);
}
public void LoadPersonColumns(DbContext dbContext, string code)
{
PersonColumns = ViewPersonColumns.GetPersonColumns(dbContext, code, PersonId);
}
public List<ViewPersonColumns> GetFormViewColumns(Int64 formId, string viewName)
{
if (PersonColumns == null)
return null;
return PersonColumns.Where(p => p.FormId == formId && p.ObjectName == viewName).ToList();
}
}
Save columns to the session
UserManagement userManagement = new UserManagement(_context, user.UserName);
userManagement.LoadPersonColumns(_context);
HttpContext.Session.SetObject("ActualPersonContext", userManagement);
HttpContext.Session.SetObject("ActualPersonColumns", userManagement.PersonColumns);
Load columns from the session
//userManagement build-in types are set. The PersonColumns is null - not correct
UserManagement userManagement = session.GetObject<UserManagement>("ActualPersonContext");
//The cols is filled from session with 600 records - correct
List<ViewPersonColumns> cols = session.GetObject<List<ViewPersonColumns>>("ActualPersonColumns");
Use list for each column is better than use database.
you can't create and store sessions in .net core like .net framework 4.0
Try Like this
Startup.cs
public void ConfigureServices(IServiceCollection services)
{
//services.AddDbContext<GeneralDBContext>(options => options.UseSqlServer(Configuration.GetConnectionString("DefaultConnection")));
services.AddMvc().AddSessionStateTempDataProvider();
services.AddSession();
}
Common/SessionExtensions.cs
sing Microsoft.AspNetCore.Http;
using Newtonsoft.Json;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
namespace IMAPApplication.Common
{
public static class SessionExtensions
{
public static T GetComplexData<T>(this ISession session, string key)
{
var data = session.GetString(key);
if (data == null)
{
return default(T);
}
return JsonConvert.DeserializeObject<T>(data);
}
public static void SetComplexData(this ISession session, string key, object value)
{
session.SetString(key, JsonConvert.SerializeObject(value));
}
}
}
Usage
==> Create Session*
public IActionResult Login([FromBody]LoginViewModel model)
{
LoggedUserVM user = GetUserDataById(model.userId);
//Create Session with complex object
HttpContext.Session.SetComplexData("loggerUser", user);
return Json(new { status = result.Status, message = result.Message });
}
==> Get Session data*
public IActionResult Index()
{
//Get Session data
LoggedUserVM loggedUser = HttpContext.Session.GetComplexData<LoggedUserVM>("loggerUser");
}
Hope this is helpful. Good luck.
This is an evergreen post, and even though Microsoft has recommended serialisation to store the object in session - it is not a correct solution unless your object is readonly, I have a blog explaining all scenario here and i have even pointed out the issues in GitHub of Asp.Net Core in issue id 18159
Synopsis of the problems are here:
A. Serialisation isn't same as object, true it will help in distributed server scenario but it comes with a caveat that Microsoft have failed to highlight - that it will work without any unpredictable failures only when the object is meant to be read and not to be written back.
B. If you were looking for a read-write object in the session, everytime you change the object that is read from the session after deserialisation - it needs to be written back to the session again by calling serialisation - and this alone can lead to multiple complexities as you will need to either keep track of the changes - or keep writing back to session after each change in any property. In one request to the server, you will have scenarios where the object is written back multiple times till the response is sent back.
C. For a read-write object in the session, even on a single server it will fail, as the actions of the user can trigger multiple rapid requests to the server and not more than often system will find itself in a situation where the object is being serialised or deserialised by one thread and being edited and then written back by another, the result is you will end up with overwriting the object state by threads - and even locks won't help you much since the object is not a real object but a temporary object created by deserialisation.
D. There are issues with serialising complex objects - it is not just a performance hit, it may even fail in certain scenario - especially if you have deeply nested objects that sometimes refer back to itself.
The synopsis of the solution is here, full implementation along with code is in the blog link:
First implement this as a Cache object, create one item in IMemoryCache for each unique session.
Keep the cache in sliding expiration mode, so that each time it is read it revives the expiry time - thereby keeping the objects in cache as long as the session is active.
Second point alone is not enough, you will need to implement heartbeat technique - triggering the call to session every T minus 1 min or so from the javascript. (This we anyways used to do even to keep the session alive till the user is working on the browser, so it won't be any different
Additional Recommendations
A. Make an object called SessionManager - so that all your code related to session read / write sits in one place.
B. Do not keep very high value for session time out - If you are implementing heartbeat technique, even 3 mins of session time out will be enough.
I am to using the CacheJdbcPojoStoreFactory
I want to have a VARCHAR field in the database which maps to an Enum in Java.
The way I am trying to achieve this is something like the following. I want the application code to work with the enum, but the persistence to use the string so that it is human readable in the database. I do not want to use int values in the database.
This seems to work fine for creating new objects, but not for reading them out. It seems that it tries to set the field directly, and the setter (setSideAsString) is not called. Of course there is no field called sideAsString. Should this work? Any suggestions?
Here is the code excerpt
In some application code I would do something like
trade.setSide(OrderSide.Buy)
And this will persist fine. I can read "Buy" in the side column as a VARCHAR.
In Trade
private OrderSide side; // OrderSide is an enum with Buy,Sell
public OrderSide getSide() {
return side;
}
public void setSide(OrderSide side) {
this.side = side;
}
public String getSideAsString() {
return this.side.name();
}
public void setSideAsString(String s) {
this.side = OrderSide.valueOf(s);
}
Now when configuring the store, I do this
Collection<JdbcTypeField> vals = new ArrayList<>();
vals.add(new JdbcTypeField(Types.VARCHAR, "side", String.class, "sideAsString"));
After a clean start, If I query Trade using Ignite SQL query, and call trade.getSide() it will be null. Other (directly mapped) columns are fine.
Thanks,
Gordon
BinaryMarshaller deserialize only fields which used in query.
Please try to use OptimizedMarshaller:
IgniteConfiguration cfg = new IgniteConfiguration();
...
cfg.setMarshaller(new OptimizedMarshaller());
Here's the ticket for support enum mapping in CacheJdbcPojoStore.
It's more like theoretical question.
I have one table to hold dictionary items, and the next one for hold Users data.
User table contains a lot reference collumns of type many to one indicated on dictionary item table. It's looks like:
public class User
{
public int Id;
public Dictionary Status;
public Dictionary Type;
public Dictionary OrganizationUnit;
......
}
I want retrieve all dictionary on startup of aplication, and then when i retrieved user and invoke reference property to dictionary the dictionary object should be taken from cache.
I know i can use a 2nd level cache in this scenario, but i'm interested about other solution. Is there any?
It's posible to make my custom type and said that: use my custom cache to retrieved value of dictionary??
Across multiple session the second level cache is the best answer, the only other solutions to populate objects from a cache without using second level cache i can think of would be to use an onLoad interceptor (and simply leave your dictionaries unmapped) or do it manually somewhere in your application.
But why don't you want to use the seocondlevel cache? If your views on caching is very different from the storages there are providers for in hibernate it is possible for you to implement your own provider?
Why not store it in the session? Just pull the record set one time and push it into session and retrieve it each time you want it. I do something similar for other stuff and I believe my method should work for you. In my code I have a session manager that I call directly from any piece of code needs the session values. I choose this method since I can query the results and I can manipulate the storage and retrieval methods. When relying on NHibernate to do the Caching for me, I don't have the granularity of control to cause specific record sets to only be available to specific sessions. I also find that NHibernate is not as efficient as using the session directly. When profiling the CPU and memory usage I find that this method is faster and uses a little less memory. If you want to do it on a site level instead of session, look into HttpContext.Current.Cache.
The following example works perfectly for storing and retrieving record sets:
// Set the session
SessionManager.User = (Some code to pull the user record with relationships. Set the fetch mode to eager for each relationship else you will just have broken references.)
// Get the session
User myUser = SessionManager.User;
public static class SessionManager
{
public static User User
{
get { return GetSession("MySessionUser") as User; }
set { SetSession("MySessionUser", value); }
}
private static object GetSession(string key)
{
// Fix Null reference error
if (System.Web.HttpContext.Current == null || System.Web.HttpContext.Current.Session == null)
{
return null;
}
else
{
return System.Web.HttpContext.Current.Session[key];
}
}
private static void SetSession(string key, object valueIn)
{
// Fix null reference error
if (System.Web.HttpContext.Current.Session[key] == null)
{
System.Web.HttpContext.Current.Session.Add(key, valueIn);
}
else
{
System.Web.HttpContext.Current.Session[key] = valueIn;
}
}
}
I'm new to NHibernate and was assigned to a task where I have to change a value of an entity property and then compare if this new value (cached) is different from the actual value stored on the DB. However, every attempt to retrieve this value from the DB resulted in the cached value. As I said, I'm new to NHibernate, maybe this is something easy to do and obviously could be done with plain ADO.NET, but the client demands that we use NHibernate for every access to the DB. In order to make things clearer, those were my "successful" attempts (ie, no errors):
1
DetachedCriteria criteria = DetachedCriteria.For<User>()
.SetProjection(Projections.Distinct(Projections.Property(UserField.JobLoad)))
.Add(Expression.Eq(UserField.Id, userid));
return GetByDetachedCriteria(criteria)[0].Id; //this is the value I want
2
var JobLoadId = DetachedCriteria.For<User>()
.SetProjection(Projections.Distinct(Projections.Property(UserField.JobLoad)))
.Add(Expression.Eq(UserField.Id, userid));
ICriteria criteria = JobLoadId.GetExecutableCriteria(NHibernateSession);
var ids = criteria.List();
return ((JobLoad)ids[0]).Id;
Hope I made myself clear, sometimes is hard to explain a problem when even you don't quite understand the underlying framework.
Edit: Of course, this is a method body.
Edit 2: I found out that it doesn't work properly for the method call is inside a transaction context. If I remove the transaction, it works fine, but I need it to be in this context.
I do that opening a new stateless session for geting the actual object in the database:
User databaseuser;
using (IStatelessSession session = SessionFactory.OpenStatelessSession())
{
databaseuser = db.get<User>("id");
}
//do your checks
Within a session, NHibernate will return the same object from its Level-1 Cache (aka Identity Map). If you need to see the current value in the database, you can open a new session and load the object in that session.
I would do it like this:
public class MyObject : Entity
{
private readonly string myField;
public string MyProperty
{
get { return myField; }
set
{
if (value != myField)
{
myField = value;
DoWhateverYouNeedToDoWhenItIsChanged();
}
}
}
}
googles nhforge
http://nhibernate.info/doc/howto/various/finding-dirty-properties-in-nhibernate.html
This may be able to help you.