Adding a new record to DB, key is always zero - entity-framework

Question

I have an existing App written using Microsoft Visual C++ 2017, ASP.NET, MVC 5.2.7.0, Entity Framework Version=5, DB is SQL Server. When I add a new record to my DB, the key (ParkID) that results is a zero and when I try and save the change. I get an error.
Cannot insert the value NULL into column 'ParkID', table 'N_CWBFM-20170818.dbo.Park'; column does not allow nulls. INSERT fails.
The database N_CWBFM-20170818 was downloaded from the HOST where my app runs.
Confession, this is a hobby, so I may not use the correct terminology and translating other ways of adding data to a DB to the method I am using.
Model
using System;
using System.ComponentModel;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
namespace CWBFM.Models
{
public class Park
{
[Key]
public int ParkID { get; set; }
public bool ParkChangePending { get; set; } // change pending true/false
public int ParkChangeCount { get; set; } // Count the number of changes to this record
public int ParkPrevRec { get; set; } // points backwards to the previous version
public int ParkNextRec { get; set; } // ID of previous record
Omitted
DB Context
using CWBFM.Models;
using System.Data.Entity;
using System.Data.Entity.ModelConfiguration.Conventions;
namespace CWBFM.DAL
{
public class CWBFMContext : DbContext
{
public DbSet<Park> Parks { get; set; }
public DbSet<Photo> Photo { get; set; }
public DbSet<StateFilter> StateFilters { get; set; }
Omitted
Controller
using System;
using System.Data;
using System.Linq;
using System.Web.Mvc;
using CWBFM.Models;
using CWBFM.DAL;
namespace CWBFM.Controllers
{
public class ParkController : BaseController
{
private CWBFMContext db = new CWBFMContext();
Omitted
// POST: /Park/Create
[HttpPost]
[Authorize]
public ActionResult ParkCreate(Park park)
{
setYesNo(); //set the values for the dropdown box (Yes, No, Unknown)
if (ModelState.IsValid)
{
park.ParkChangePending = false;
park.ParkChangeCount = 0;
park.ParkDateCreated = DateTime.Now;
park.ParkDateChange = DateTime.Now;
park.ParkCreatedBy = #User.Identity.Name;
park.ParkChangedBy = #User.Identity.Name;
park.ParkStatus = "N";
db.Parks.Add(park);
int stop = park.ParkID;
db.SaveChanges();
park.ParkRecID = "Park" + park.ParkID.ToString();
db.SaveChanges();
return RedirectToAction("ParkDetails", new { id=park.ParkID });
}
return View(park);
}
Config
<?xml version="1.0" encoding="utf-8"?>
<!--
For more information on how to configure your ASP.NET application, please visit
http://go.microsoft.com/fwlink/?LinkId=152368
-->
<configuration>
<configSections>
<!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 -->
<!-- <section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" /> -->
<section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=5.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" />
</configSections>
<appSettings>
<add key="webpages:Version" value="3.0.0.0" />
<add key="webpages:Enabled" value="false" />
<add key="ClientValidationEnabled" value="true" />
<add key="UnobtrusiveJavaScriptEnabled" value="true" />
</appSettings>
<system.web>
<compilation debug="true" targetFramework="4.6.1" />
<authentication mode="Forms">
<forms loginUrl="~/Account/LogOn" timeout="2880" />
</authentication>
<pages>
<namespaces>
<add namespace="System.Web.Helpers" />
<add namespace="System.Web.Mvc" />
<add namespace="System.Web.Mvc.Ajax" />
<add namespace="System.Web.Mvc.Html" />
<add namespace="System.Web.Routing" />
<add namespace="System.Web.WebPages" />
<add namespace="Telerik.Web.Mvc.UI" />
</namespaces>
</pages>
<httpRuntime targetFramework="4.6.1" maxRequestLength="20971520" />
<!-- This will handle requests up to 20MB -->
<profile inherits="CWBFM.Models.MyUserProfile" defaultProvider="DefaultProvider">
<providers>
<clear />
<add name="DefaultProvider" type="System.Web.Providers.DefaultProfileProvider, System.Web.Providers, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" connectionStringName="DefaultConnection" applicationName="/" />
</providers>
</profile>
<!--<profile defaultProvider="DefaultProfileProvider">
<providers>
<add name="DefaultProfileProvider" type="System.Web.Providers.DefaultProfileProvider, System.Web.Providers, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" connectionStringName="DefaultConnection" applicationName="/" />
</providers>
</profile>-->
<membership defaultProvider="DefaultMembershipProvider">
<providers>
<add name="DefaultMembershipProvider" type="System.Web.Providers.DefaultMembershipProvider, System.Web.Providers, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" connectionStringName="DefaultConnection" enablePasswordRetrieval="false" enablePasswordReset="true" requiresQuestionAndAnswer="false" requiresUniqueEmail="false" maxInvalidPasswordAttempts="5" minRequiredPasswordLength="6" minRequiredNonalphanumericCharacters="0" passwordAttemptWindow="10" applicationName="/" />
</providers>
</membership>
<roleManager enabled="true" defaultProvider="DefaultRoleProvider">
<providers>
<add connectionStringName="DefaultConnection" applicationName="/" name="DefaultRoleProvider" type="System.Web.Providers.DefaultRoleProvider, System.Web.Providers, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" />
</providers>
</roleManager>
<!--
If you are deploying to a cloud environment that has multiple web server instances,
you should change session state mode from "InProc" to "Custom". In addition,
change the connection string named "DefaultConnection" to connect to an instance
of SQL Server (including SQL Azure and SQL Compact) instead of to SQL Server Express.
-->
<sessionState mode="InProc" customProvider="DefaultSessionProvider">
<providers>
<add name="DefaultSessionProvider" type="System.Web.Providers.DefaultSessionStateProvider, System.Web.Providers, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" connectionStringName="DefaultConnection" />
</providers>
</sessionState>
<httpHandlers>
<add verb="GET,HEAD" path="asset.axd" validate="false" type="Telerik.Web.Mvc.WebAssetHttpHandler, Telerik.Web.Mvc" />
</httpHandlers>
<httpModules>
<add name="CompilableFileModule" type="SassAndCoffee.CompilableFileModule" />
</httpModules>
</system.web>
<system.webServer>
<security>
<requestFiltering>
<!-- This will handle requests up to 1024MB (1GB) -->
<requestLimits maxAllowedContentLength="1073741824" />
</requestFiltering>
</security>
<validation validateIntegratedModeConfiguration="false" />
<handlers>
<remove name="asset" />
<add name="asset" preCondition="integratedMode" verb="GET,HEAD" path="asset.axd" type="Telerik.Web.Mvc.WebAssetHttpHandler, Telerik.Web.Mvc" />
<remove name="ExtensionlessUrlHandler-Integrated-4.0" /><remove name="OPTIONSVerbHandler" /><remove name="TRACEVerbHandler" /><add name="ExtensionlessUrlHandler-Integrated-4.0" path="*." verb="*" type="System.Web.Handlers.TransferRequestHandler" preCondition="integratedMode,runtimeVersionv4.0" /></handlers>
<modules>
<remove name="CompilableFileModule" />
<add name="CompilableFileModule" type="SassAndCoffee.CompilableFileModule" />
</modules>
</system.webServer>
<runtime>
<assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
<dependentAssembly>
<assemblyIdentity name="System.Web.Helpers" publicKeyToken="31bf3856ad364e35" />
<bindingRedirect oldVersion="1.0.0.0-3.0.0.0" newVersion="3.0.0.0" />
</dependentAssembly>
<dependentAssembly>
<assemblyIdentity name="System.Web.WebPages" publicKeyToken="31bf3856ad364e35" />
<bindingRedirect oldVersion="0.0.0.0-3.0.0.0" newVersion="3.0.0.0" />
</dependentAssembly>
<dependentAssembly>
<assemblyIdentity name="System.Web.Mvc" publicKeyToken="31bf3856ad364e35" />
<bindingRedirect oldVersion="0.0.0.0-5.2.7.0" newVersion="5.2.7.0" />
</dependentAssembly>
<dependentAssembly>
<assemblyIdentity name="System.Net.Http.Formatting" publicKeyToken="31bf3856ad364e35" culture="neutral" />
<bindingRedirect oldVersion="0.0.0.0-5.2.7.0" newVersion="5.2.7.0" />
</dependentAssembly>
</assemblyBinding>
</runtime>
<entityFramework>
<defaultConnectionFactory type="System.Data.Entity.Infrastructure.LocalDbConnectionFactory, EntityFramework">
<parameters>
<parameter value="v11.0" />
</parameters>
</defaultConnectionFactory>
</entityFramework>
<connectionStrings>
It dies on the save (db.SaveChanges();). A breakpoint at int stop = park.ParkID; shows that the ParkID is zero.
ParkID = 0
I have looked at several proposed solutions, but just can’t find one that works. Any suggestions. Could I have missed an update in my config when I changed to EF 5?

Answer 1

This can occur if the database was set up without an Identity column set on the PK, but EF will automatically expect an identity column on keys named "Id" or with the "Id" suffix on the class name. (I.e. Park.ParkId) If the DB is not actually set up to use an Identity but EF is configured for an Identity column (DatabaseGeneratedOption.Identity) the resulting insert statements will not include the ParkId column, resulting in a #null failure in the database.
I generally recommend being explicit with configuration rather than relying on EF's conventions for behaviour:
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int ParkId { get; set; }
If you expect the new records to be given a PK value automatically by the database then update the database schema to mark these PKs as Identity columns. If your schema is code-first and generating Migrations then there should be a way to apply a migration to update the PKs to identity columns. Otherwise simply make the change within SSMS.
If instead you want to provide PKs from your code, (such as part of data imports from other data sources) then you need to configure EF to not treat the PK as an Identity.
[DatabaseGenerated(DatabaseGeneratedOption.None)]
public int ParkId { get; set; }