Databases
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POUnable to determine the principal end of OR “Value cannot be null, parameter name 'key'”
 

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    <p>I have tried almost everything from StackOverflow to prevent these errors. I have no idea what am I doing wrong. When I'm starting with some changes to remove one bug, the second appear and vice versa. I don't know if it connects to DB, or can it initialize DB, or cannot. It looks like my DB file is empty - I'm using SQLite and I want to use Code First mechanism of EF.</p> <p>My code</p> <pre><code>using System.Data.Entity; using ControlCenter; namespace ControlCenter { public class IncomingMessaggesContext: DbContext { public DbSet&lt;UnifiedPositionMessage&gt; UnifiedPositionMessages { get; set; } public DbSet&lt;MessageDescription&gt; MessageDescriptions { get; set; } static IncomingMessaggesContext() { Database.SetInitializer&lt;IncomingMessaggesContext&gt;(null); } } } using System.ComponentModel.DataAnnotations; using System.ComponentModel.DataAnnotations.Schema; namespace ControlCenter.CommunicationGateway { using System; using TrackingDevices.Positioning; public class UnifiedPositionMessage { public int Id { get; set; } public uint DeviceID { get; set; } public DateTime ReceiveTime { get; set; } public PositionBase DevicePosition { get; set; } public object UserPayload { get; set; } public int MessageDescriptionId { get; set; } [ForeignKey("Id")] [Required] public virtual MessageDescription MessageDescription { get; set; } } public class MessageDescription { public int Id { get; set; } public bool IsMessageValid { get; set; } public virtual UnifiedPositionMessage UnifiedPositionMessage { get; set; } } } </code></pre> <p>Calling DB</p> <pre><code>using (var db = new IncomingMessaggesContext() ) { var msgDesc = new MessageDescription() {IsMessageValid = true, Id = 0, UnifiedPositionMessage = e.Frame}; db.MessageDescriptions.Add(msgDesc); db.UnifiedPositionMessages.Add(e.Frame); db.SaveChanges(); } </code></pre> <p>And connection settings</p> <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt; &lt;configuration&gt; &lt;configSections&gt; &lt;!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 --&gt; &lt;section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=4.4.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" /&gt; &lt;/configSections&gt; &lt;entityFramework&gt; &lt;connectionStrings&gt; &lt;add name="IncomingMessaggesContext" connectionString="Data Source=c:\temp\Messages.db;" providerName="System.Data.SQLite" /&gt; &lt;/connectionStrings&gt; &lt;defaultConnectionFactory type="System.Data.Entity.Infrastructure.SqlConnectionFactory, EntityFramework" /&gt; &lt;/entityFramework&gt; &lt;system.data&gt; &lt;DbProviderFactories&gt; &lt;add name="SQLite Data Provider" invariant="System.Data.SQLite" description="Data Provider for SQLite" type="System.Data.SQLite.SQLiteFactory, System.Data.SQLite" /&gt; &lt;/DbProviderFactories&gt; &lt;/system.data&gt; &lt;/configuration&gt; </code></pre>
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