MySQL /实体框架-生成模型时发生错误“ RelationshipDetails中列“ FkColumn为DBNull”的值”

Question

I am trying to use MySql 5.1 with Entity Framework 6.0 and the DbContext generator 5.0, with .Net Framework 4.0, Visual Studio 2010 and C#. I have downloaded the most recent packages from NuGet. I am able to add tables from the database to the model with no problems up to a point (which I have had difficulties pinning down). After that point, trying to add new tables or even generating the existing model gives the error shown below:

Unable to generate the model because of the following exception: 'The value for column 'FkColumn' in table 'RelationshipDetails' is DBNull.
Unable to cast object of type 'System.DBNull' to type 'System.String'.

I have tried turning on debug in the .tt file, but the exception occurs before the .tt file is loaded and being parsed. I have also tried deleting tables, but the error continues to occur when I try and upload new tables from the database, or try to save the existing file. Oddly enough, the tt template does get called, and generats the classes. But it will not load any new tables from the database. When you run the debugger on the template, you get the following message:

Error   2   An Exception was thrown while running the transformation code. The process cannot continue.  The following Exception was thrown:
System.Runtime.Remoting.RemotingException: Object '/9747a151_8703_4922_90da_93472afe62d2/fjgxduxp4yb2qwls+ipl7t98_89.rem' has been disconnected or does not exist at the server.
   at Microsoft.VisualStudio.TextTemplating.TransformationRunner.get_Errors()
   at Microsoft.VisualStudio.TextTemplating.Engine.CompileAndRunCode(String generatorCode, ITextTemplatingEngineHost host, TemplateProcessingSession session)       C:\Development\CCBPlus\CCB Server\Model\CCBPlus.tt  0   0   

Does any one have any suggestions on how to proceed on this? I am at a standstill and have deleted and recreated my model 3 times now, without getting any closer to figuring out what is causing this.

Thanks, Neil

A little bit more research seems to indicate that once an entity named Contact is defined, adding any further entities that link to that entity causes the error. I can add other entities that are not linked to the Contact, without problems. The Contact entity is defined as follows:

     <EntityType Name="Contact">
      <Key>
        <PropertyRef Name="ContactId" />
      </Key>
      <Property Type="Int32" Name="ContactId" Nullable="false" annotation:StoreGeneratedPattern="Identity" />
      <Property Type="Byte" Name="ContactType" Nullable="false" />
      <Property Type="String" Name="DisplayName" Nullable="false" MaxLength="80" FixedLength="false" Unicode="false" />
      <Property Type="String" Name="SearchName" Nullable="false" MaxLength="80" FixedLength="false" Unicode="false" />
      <Property Type="String" Name="Prefix" MaxLength="15" FixedLength="false" Unicode="false" />
      <Property Type="String" Name="LastName" MaxLength="50" FixedLength="false" Unicode="false" />
      <Property Type="String" Name="Initials" MaxLength="10" FixedLength="false" Unicode="false" />
      <Property Type="String" Name="FirstName" MaxLength="40" FixedLength="false" Unicode="false" />
      <Property Type="String" Name="Suffix" MaxLength="10" FixedLength="false" Unicode="false" />
      <Property Type="String" Name="OrganizationName" MaxLength="50" FixedLength="false" Unicode="false" />
      <Property Type="String" Name="InCareOf" MaxLength="80" FixedLength="false" Unicode="false" />
      <Property Type="DateTime" Name="Birthdate" />
      <Property Type="DateTime" Name="Deceased" />
      <Property Type="String" Name="SocialSecurityNumber" MaxLength="20" FixedLength="false" Unicode="false" />
      <Property Type="SByte" Name="Gender" />
      <Property Type="String" Name="CulturePreference" MaxLength="10" FixedLength="false" Unicode="false" />
      <Property Type="DateTime" Name="LastMeeting" />
      <Property Type="String" Name="Hobbies" MaxLength="100" FixedLength="false" Unicode="false" />
      <Property Type="String" Name="Notes" MaxLength="1073741823" FixedLength="false" Unicode="false" />
      <Property Type="Boolean" Name="Inactive" Nullable="false" />
      <Property Type="DateTime" Name="Created" Nullable="false" />
      <Property Type="DateTime" Name="LastModified" Nullable="false" />
      <NavigationProperty Name="AccountHolders" Relationship="CCB.EntityModel.fk_AccountHolder_Contact" FromRole="Contact" ToRole="AccountHolder" />
      <NavigationProperty Name="Branches" Relationship="CCB.EntityModel.fk_Branch_ContactInfo" FromRole="Contact" ToRole="Branch" />
      <NavigationProperty Name="Company" Relationship="CCB.EntityModel.fk_Company_ContactInfo" FromRole="Contact" ToRole="Company" />
      <NavigationProperty Name="ContactCategories" Relationship="CCB.EntityModel.fk_ContactCategory_Contact" FromRole="Contact" ToRole="ContactCategory" />
      <NavigationProperty Name="ContactCommunications" Relationship="CCB.EntityModel.fk_ContactCommunication_Contact" FromRole="Contact" ToRole="ContactCommunication" />
      <NavigationProperty Name="Agents" Relationship="CCB.EntityModel.fk_Agent_ContactInfo" FromRole="Contact" ToRole="Agent" />
    </EntityType>
    <Association Name="fk_AccountHolder_Contact">
      <End Type="CCB.EntityModel.Contact" Role="Contact" Multiplicity="1" />
      <End Type="CCB.EntityModel.AccountHolder" Role="AccountHolder" Multiplicity="*" />
      <ReferentialConstraint>
        <Principal Role="Contact">
          <PropertyRef Name="ContactId" />
        </Principal>
        <Dependent Role="AccountHolder">
          <PropertyRef Name="ContactId" />
        </Dependent>
      </ReferentialConstraint>
    </Association>
    <Association Name="fk_Branch_ContactInfo">
      <End Type="CCB.EntityModel.Contact" Role="Contact" Multiplicity="1" />
      <End Type="CCB.EntityModel.Branch" Role="Branch" Multiplicity="*" />
    </Association>
    <Association Name="fk_Company_ContactInfo">
      <End Type="CCB.EntityModel.Contact" Role="Contact" Multiplicity="1" />
      <End Type="CCB.EntityModel.Company" Role="Company" Multiplicity="0..1" />
      <ReferentialConstraint>
        <Principal Role="Contact">
          <PropertyRef Name="ContactId" />
        </Principal>
        <Dependent Role="Company">
          <PropertyRef Name="CompanyContactId" />
        </Dependent>
      </ReferentialConstraint>
    </Association>
    <Association Name="fk_ContactCategory_Contact">
      <End Type="CCB.EntityModel.Contact" Role="Contact" Multiplicity="1" />
      <End Type="CCB.EntityModel.ContactCategory" Role="ContactCategory" Multiplicity="*" />
      <ReferentialConstraint>
        <Principal Role="Contact">
          <PropertyRef Name="ContactId" />
        </Principal>
        <Dependent Role="ContactCategory">
          <PropertyRef Name="ContactId" />
        </Dependent>
      </ReferentialConstraint>
    </Association>
    <Association Name="fk_ContactCommunication_Contact">
      <End Type="CCB.EntityModel.Contact" Role="Contact" Multiplicity="1" />
      <End Type="CCB.EntityModel.ContactCommunication" Role="ContactCommunication" Multiplicity="*" />
    </Association>

The MySQL table definition is:

CREATE TABLE `Contacts` (
   `ContactId` int(11) NOT NULL,
   `ContactType` bit(3) NOT NULL COMMENT 'Contact Type: 0=Individual, 1=Corporate, 2=Family, 3=Branch, 4=Department, 5=Group, 6=Fund/GIC/Bank company',
   `DisplayName` varchar(80) NOT NULL,
   `SearchName` varchar(80) NOT NULL,
   `Prefix` varchar(15) DEFAULT NULL,
   `LastName` varchar(50) DEFAULT NULL,
   `Initials` varchar(10) DEFAULT NULL,
   `FirstName` varchar(40) DEFAULT NULL,
   `Suffix` varchar(10) DEFAULT NULL,
   `OrganizationName` varchar(50) DEFAULT NULL,
   `InCareOf` varchar(80) DEFAULT NULL COMMENT 'If mail is to be sent with the line "In care of [X]"',
   `Birthdate` datetime DEFAULT NULL,
   `Deceased` datetime DEFAULT NULL,
   `SocialSecurityNumber` varchar(20) DEFAULT NULL,
   `Gender` bit(1) DEFAULT b'0' COMMENT '0=Male,1=Female',
   `CulturePreference` varchar(10) DEFAULT 'EN-CA' COMMENT 'Global Culture variable, e.g. EN-CA or FR-CA or other.',
   `LastMeeting` datetime DEFAULT NULL,
   `Hobbies` varchar(100) DEFAULT NULL,
   `Inactive` tinyint(1) NOT NULL DEFAULT '0',
   `Created` datetime NOT NULL,
   `LastModified` datetime NOT NULL,
   PRIMARY KEY (`ContactId`)
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8 COMMENT='Stores contact and optionally personal information';

Answer 1

I finally deleted the database and recreated it from the MySQL Workbench model and the problem went away. Clearly, something in MySQL was corrupted from the repeated uploads from the Model. However, recreating from the model created a different problem, described here . The fun never stops when you work with OpenSource!