问题
I have a fairly large data model that I want to expose using Web API OData using the OData V4 protocol.
The underlying data is stored in a SQL Server 2012 database. That database has many DateTime columns in it.
As I was wiring it up I got an error that System.DateTime is not supported.
So here is my question, what can I do to get my DateTime columns to be seen in the OData feed?
NOTE: I am not able to go back and change all my columns to DateTimeOffset columns.
I tried changing the type of the column in the Entity Framework edmx, but it gave me this error:
Member Mapping specified is not valid. The type 'Edm.DateTimeOffset[Nullable=False,DefaultValue=,Precision=]' of member 'MyPropertyHere' in type 'MyProject.MyEntity' is not compatible with 'SqlServer.datetime[Nullable=False,DefaultValue=,Precision=3]' of member 'MyColumnName' in type 'MyDataModel.Store.MyEntity'.
(Bascially syas that DateTime is not compatable with DateTimeOffset.)
Did the Web API OData team really just leave out everyone who needs to use the SQL Server type of DateTime?
Update: I have found workarounds for this, but they require updating the EF Model for them to work. I would rather not have to update several hundred properties individually if I can avoid it.
Update: This issue has made me realize that there are deep flaws in how Microsoft is managing its OData products. There are many issues, but this one is the most glaring. There are huge missing features in the Web API OData. Transactions and ordering of inserts being two of them. These two items (that are in the OData spec and were in WCF Data Services before Microsoft killed it) are critical to any real system.
But rather than put time into those critical spots where they are missing functionality that is in the OData Specification, they decide to spend their time on removing functionality that was very helpful to many developers. It epitomizes bad management to prioritize the removal of working features over adding in badly needed features.
I tried discussing these with the Web API OData representative, and in the end, I got a issue/ticket opened that was then closed a few days later. That was the end of what they were willing to do.
As I said, there are many more issues (not related to DateTime, so I will not list them here) with the management of Web API OData. I have been a very strong supporter of OData, but the glaring issues with Web API OData's management have forced me and my team/company to abandon it.
Fortunately, normal Web API can be setup to use OData syntax. It is more work to setup your controllers, but it works just fine in the end. And it supports DateTime. (And seems to have management that can at least stay away from making insanely bad decisions.)
回答1:
So far, DateTime is not the part of the OASIS OData V4 standard and Web API doesn't support the DateTime type while it do support the DateTimeOffset type.
However, OData Team are working on supporting the DataTime type now. I'd expect you can use the DateTime type in the next Web API release. If you can't wait for the next release, I wrote an example based on the blog . Hope it can help you. Thanks.
Model
public class Customer
{
private DateTimeWrapper dtw;
public int Id { get; set; }
public string Name { get; set; }
public DateTime Birthday
{
get { return dtw; }
set { dtw = value; }
}
[NotMapped]
public DateTimeOffset BirthdayOffset
{
get { return dtw; }
set { dtw = value; }
}
}
public class DateTimeWrapper
{
public static implicit operator DateTimeOffset(DateTimeWrapper p)
{
return DateTime.SpecifyKind(p._dt, DateTimeKind.Utc);
}
public static implicit operator DateTimeWrapper(DateTimeOffset dto)
{
return new DateTimeWrapper(dto.DateTime);
}
public static implicit operator DateTime(DateTimeWrapper dtr)
{
return dtr._dt;
}
public static implicit operator DateTimeWrapper(DateTime dt)
{
return new DateTimeWrapper(dt);
}
protected DateTimeWrapper(DateTime dt)
{
_dt = dt;
}
private readonly DateTime _dt;
}
DB Context
public DbSet<Customer> Customers { get; set; }
EdmModel
ODataConventionModelBuilder builder = new ODataConventionModelBuilder();
builder.EntitySet<Customer>("Customers");
var cu = builder.StructuralTypes.First(t => t.ClrType == typeof(Customer));
cu.AddProperty(typeof(Customer).GetProperty("BirthdayOffset"));
var customer = builder.EntityType<Customer>();
customer.Ignore(t => t.Birthday);
var model = builder.GetEdmModel();
config.MapODataServiceRoute("odata", "odata", model);
Controller
Add the OData Controller as normal.
Test
Payload
回答2:
Finally Web API OData v4 now supports DateTime type in release 5.5 . Get latest nuget package and don't forget setting this:
config.SetTimeZoneInfo(TimeZoneInfo.Utc);
otherwise the timezone of the dateTime property would be considered as local timezone.
More info: ASP.NET Web API for OData V4 Docs DateTime support
回答3:
An alternate solution is to patch the project so that DateTime is allowed again - that's what I did, you can get the code here if you want it:
https://aspnetwebstack.codeplex.com/SourceControl/network/forks/johncrim/datetimefixes
I also pushed a NuGet package to make it easy to use, you can obtain the package using the info here:
http://www.nuget.org/packages/Patches.System.Web.OData/5.3.0-datetimefixes
... I don't know if it's ok for me to post a NuGet package containing a patched Microsoft library, I hope it's easier to ask forgiveness than permission.
Note that the work item to officially restore the ability to use DateTime in OData 4 is tracked here: https://aspnetwebstack.codeplex.com/workitem/2072 Please vote for the issue if you'd like to see it; though it looks like it's scheduled for 5.4-beta, so it should be coming one of these days.
回答4:
This workarounds and the one from http://damienbod.wordpress.com/2014/06/16/web-api-and-odata-v4-crud-and-actions-part-3/, neither work. They work one way only, meaning that quering odata datetimeoffset with the filter command fails because it is not part of the model.
You can no longer filter or sort by these fields or get this error
/Aas/Activities?$top=11&$orderby=CreatedAt
Gives this error:
"code":"","message":"An error has occurred.","innererror":{
"message":"The 'ObjectContent`1' type failed to serialize the response body for content type 'application/json; odata.metadata=minimal'.","type":"System.InvalidOperationException","stacktrace":"","internalexception":{
"message":"The specified type member 'CreatedAt' is not supported in LINQ to Entities. Only initializers, entity members, and entity navigation properties are supported.","type":"System.NotSupportedException","stacktrace":"
But this works as it is addressed indirectly:
/Aas/AppUsers%28102%29/AppUserActivities?$expand=Case&$filter=%28Reminder%20ne%20null%20and%20IsComplete%20eq%20null%29&$top=15&$orderby=Reminder&$count=true
Reminder and Iscomplete are date and datetiem from activity through AppUserActivities.
This is wierd that that works. Does anyone have a solution?
I connect to MySQL. There is not a datetimeoffset.
And everyone wonders why no one wants to develop for Microsoft technologies.
回答5:
Unfortunatly, https://aspnetwebstack.codeplex.com/SourceControl/network/forks/johncrim/datetimefixes fork, given by crimbo doesn`t realy support DateTime.
There is the new fork https://aspnetwebstack.codeplex.com/SourceControl/network/forks/kj/odata53datetime?branch=odata-v5.3-rtm based on OData v5.3 RTM, where DateTime properties in entities and complex types are supported in server answers, client POST/PUT/PATCH requests, $orderby and $filters clauses, function parameters and returns. We start to use it in production code and will support this fork, until DateTime support will return in future official releases.
回答6:
Since i use a library for odata with angular, i investigated it there:
https://github.com/devnixs/ODataAngularResources/blob/master/src/odatavalue.js
There you can see ( javascript)
var generateDate = function(date,isOdataV4){
if(!isOdataV4){
return "datetime'" + date.getFullYear() + "-" + ("0" + (date.getMonth() + 1)).slice(-2) + "-" + ("0" + date.getDate()).slice(-2) + "T" + ("0" + date.getHours()).slice(-2) + ":" + ("0" + date.getMinutes()).slice(-2)+':'+("0" + date.getSeconds()).slice(-2) + "'";
}else{
return date.getFullYear() + "-" + ("0" + (date.getMonth() + 1)).slice(-2) + "-" + ("0" + date.getDate()).slice(-2) + "T" + ("0" + date.getHours()).slice(-2) + ":" + ("0" + date.getMinutes()).slice(-2)+':'+("0" + date.getSeconds()).slice(-2) + "Z";
}
};
And the test expects ( cfr. here )
$httpBackend.expectGET("/user(1)?$filter=date eq 2015-07-28T10:23:00Z")
So this should be your "formatting"
2015-07-28T10:23:00Z
回答7:
public class Customer
{
private DateTimeWrapper dtw;
public int Id { get; set; }
public string Name { get; set; }
public DateTime Birthday
{
get { return dtw; }
set { dtw = value; }
}
[NotMapped]
public DateTimeOffset BirthdayOffset
{
get { return dtw; }
set { dtw = value; }
}
}
var customer = builder.EntityType<Customer>();
customer.Ignore(t => t.Birthday);
customer.Property(t => t.BirthdayOffset).Name = "Birthday";
回答8:
Looks like a mapping DateTimeOffset <-> DateTime will be included in Microsoft ASP.NET Web API 2.2 for OData v4.0 5.4.0:
https://github.com/OData/WebApi/commit/2717aec772fa2f69a2011e841ffdd385823ae822
回答9:
Install System.Web.OData 5.3.0-datetimefixes from https://www.nuget.org/packages/Patches.System.Web.OData/
回答10:
Having spent a frustrating day trying to do this very thing, I have just stumbled across the only way I could get it to work. We wanted to be able to filter by date ranges using OData and Web API 2.2, which isn't an uncommon use case. Our data is in SQL Server and is stored as DateTime and we're using EF in the API.
Versions:
- Microsoft.AspNet.WebApi.OData 5.7.0
- Microsoft.AspNet.Odata 5.9.0
- Microsoft.OData.Core 6.15.0
- Microsoft.OData.Edm 6.15.0
- Microsoft.Data.OData 5.7.0
Entity Snippet:
[Table("MyTable")]
public class CatalogueEntry
{
[Key]
public Guid ContentId { get; set; }
[StringLength(15)]
public string ProductName { get; set; }
public int EditionNumber { get; set; }
public string Purpose { get; set; }
public DateTime EditionDate { get; set; }
}
WebApiConfig
public static class WebApiConfig
{
public static void Register(HttpConfiguration config)
{
config.Routes.MapODataServiceRoute("ProductCatalogue", "odata", GetImplicitEdm());
// Web API routes
config.MapHttpAttributeRoutes();
config.Filters.Add(new UnhandledExceptionFilter());
var includeVersionHeaders = ConfigurationManager.AppSettings["IncludeVersionHeaders"];
if (includeVersionHeaders != null && bool.Parse(includeVersionHeaders))
{
config.Filters.Add(new BuildVersionHeadersFilter());
}
config.SetTimeZoneInfo(TimeZoneInfo.Utc);
}
private static IEdmModel GetImplicitEdm()
{
ODataModelBuilder builder = new ODataConventionModelBuilder();
builder.EntitySet<CatalogueEntry>("ProductCatalogue");
return builder.GetEdmModel();
}
}
Controller Snippet:
public class ProductCatalogueController : EntitySetController<CatalogueEntry, string>
{
[EnableQuery]
public override IQueryable<CatalogueEntry> Get()
{
return _productCatalogueManager.GetCatalogue().AsQueryable();
}
protected override CatalogueEntry GetEntityByKey(string key)
{
return _productCatalogueManager.GetCatalogue().FirstOrDefault(c => c.ContentId.ToString() == key);
}
}
Here's the magic bit - see the bottom of this MSDN page under the heading 'Referencing Different Data Types in Filter Expressions' and you will find a note saying:
DateTime values must be delimited by single quotation marks and preceded by the word datetime, such as datetime'2010-01-25T02:13:40.1374695Z'.
http://localhost/Product-Catalogue/odata/ProductCatalogue?$filter=EditionDate lt datetime'2014-05-15T00:00:00.00Z'
So far we have this working in Postman and we're now building the client which should hopefully work with this requirement to stick 'datetime' in front of the actual value. I'm looking at using Simple.OData.Client in an MVC controller but we may even decide to call straight to the API from client side JavaScript depending on how much refactoring we have to do. I'd also like to get Swagger UI working using Swashbuckle.OData but this is also proving to be tricky. Once I've done as much as I have time to, I'll post an update with useful info for those who follow as I found it very frustrating that it was so hard to find out how to do something that is ostensibly a simple requirement.
回答11:
Both the following work with ODATA 4
this is the Latest update I see with .Net 4.7 and Microsoft.Aspnet.ODATA 5.3.1
$filter=DateofTravel lt cast(2018-05-15T00:00:00.00Z,Edm.DateTimeOffset)
this also works , it needs to be in this yyyy-mm-ddThh:mm:ss.ssZ
$filter=DateofTravel lt 2018-02-02T00:00:00.00Z
来源：https://stackoverflow.com/questions/25189557/how-to-get-web-api-odata-v4-to-use-datetime