.net实体类更新的方法(没有办法的办法)

采用此方法时，强烈建议，更新前，先将model层的代码拷贝出来，或是上传到版本控制工具上。

整体思路：

1.model层的代码备份

2.删除以前的edmx文件，新增新的edmx(只含有想添加的表)

3.拷贝出生成的文件(edmx对应的xml和实体类.cs)

4.删除刚生成的edmx，恢复成原始状态

5.以xml打开原始状态的edmx文件，将新生成的edmx相应节点放进原始edmx文件中

6.将拷贝出的实体类.cs放到model层中

7.找到继承DbContext的类，声明生成的对应的实体类

1.自行选择model层的备份方式

2.删除.edmx文件-->右击model文件夹-->添加-->新建项-->搜索ado-->输入名称-->添加-->来自数据库EF设计器-->下一步-->是

选中想更新的表或视图，单击完成

 

3.拷贝出生成的文件

右击.edmx文件--->选择打开方式--->选择xml文本编辑器--->确定

将生成的edmx文件以xml形式读取，全都拷贝到记事本中

<?xml version="1.0" encoding="utf-8"?>
<edmx:Edmx Version="3.0" xmlns:edmx="http://schemas.microsoft.com/ado/2009/11/edmx">
  <!-- EF Runtime content -->
  <edmx:Runtime>
    <!-- SSDL content -->
    <edmx:StorageModels>
      <Schema Namespace="OnlineEDUModel.Store" Provider="System.Data.SqlClient" ProviderManifestToken="2008" Alias="Self" xmlns:store="http://schemas.microsoft.com/ado/2007/12/edm/EntityStoreSchemaGenerator" xmlns:customannotation="http://schemas.microsoft.com/ado/2013/11/edm/customannotation" xmlns="http://schemas.microsoft.com/ado/2009/11/edm/ssdl">
        <!--生成过程中发现错误:
警告 6002: 表/视图“OnlineEDU.dbo.view_area”未定义主键。已推断出该键，并将定义创建为只读的表/视图。-->
        <EntityType Name="view_area">
          <Key>
            <PropertyRef Name="UserId" />
            <PropertyRef Name="RoleId" />
            <PropertyRef Name="username" />
            <PropertyRef Name="Credit" />
          </Key>
          <Property Name="col" Type="bigint" />
          <Property Name="UserId" Type="nvarchar" MaxLength="128" Nullable="false" />
          <Property Name="RoleId" Type="nvarchar" MaxLength="128" Nullable="false" />
          <Property Name="username" Type="nvarchar" MaxLength="32" Nullable="false" />
          <Property Name="school" Type="nvarchar" MaxLength="32" />
          <Property Name="firsttime" Type="datetime" />
          <Property Name="Credit" Type="bigint" Nullable="false" />
          <Property Name="Province" Type="nvarchar" MaxLength="50" />
          <Property Name="City" Type="nvarchar" MaxLength="50" />
          <Property Name="Area" Type="nvarchar" MaxLength="50" />
        </EntityType>
        <!--生成过程中发现错误:
警告 6002: 表/视图“OnlineEDU.dbo.view_teacher”未定义主键。已推断出该键，并将定义创建为只读的表/视图。-->
        <EntityType Name="view_teacher">
          <Key>
            <PropertyRef Name="UserId" />
            <PropertyRef Name="RoleId" />
            <PropertyRef Name="username" />
            <PropertyRef Name="Credit" />
          </Key>
          <Property Name="col" Type="bigint" />
          <Property Name="UserId" Type="nvarchar" MaxLength="128" Nullable="false" />
          <Property Name="RoleId" Type="nvarchar" MaxLength="128" Nullable="false" />
          <Property Name="username" Type="nvarchar" MaxLength="32" Nullable="false" />
          <Property Name="school" Type="nvarchar" MaxLength="32" />
          <Property Name="firsttime" Type="datetime" />
          <Property Name="Province" Type="nvarchar" MaxLength="50" />
          <Property Name="City" Type="nvarchar" MaxLength="50" />
          <Property Name="Area" Type="nvarchar" MaxLength="50" />
          <Property Name="Credit" Type="bigint" Nullable="false" />
        </EntityType>
        <EntityContainer Name="OnlineEDUModelStoreContainer">
          <EntitySet Name="view_area" EntityType="Self.view_area" store:Type="Views" store:Schema="dbo">
            <DefiningQuery>SELECT 
    [view_area].[col] AS [col], 
    [view_area].[UserId] AS [UserId], 
    [view_area].[RoleId] AS [RoleId], 
    [view_area].[username] AS [username], 
    [view_area].[school] AS [school], 
    [view_area].[firsttime] AS [firsttime], 
    [view_area].[Credit] AS [Credit], 
    [view_area].[Province] AS [Province], 
    [view_area].[City] AS [City], 
    [view_area].[Area] AS [Area]
    FROM [dbo].[view_area] AS [view_area]</DefiningQuery>
          </EntitySet>
          <EntitySet Name="view_teacher" EntityType="Self.view_teacher" store:Type="Views" store:Schema="dbo">
            <DefiningQuery>SELECT 
    [view_teacher].[col] AS [col], 
    [view_teacher].[UserId] AS [UserId], 
    [view_teacher].[RoleId] AS [RoleId], 
    [view_teacher].[username] AS [username], 
    [view_teacher].[school] AS [school], 
    [view_teacher].[firsttime] AS [firsttime], 
    [view_teacher].[Province] AS [Province], 
    [view_teacher].[City] AS [City], 
    [view_teacher].[Area] AS [Area], 
    [view_teacher].[Credit] AS [Credit]
    FROM [dbo].[view_teacher] AS [view_teacher]</DefiningQuery>
          </EntitySet>
        </EntityContainer>
      </Schema>
    </edmx:StorageModels>
    <!-- CSDL content -->
    <edmx:ConceptualModels>
      <Schema Namespace="OnlineEDUModel" Alias="Self" annotation:UseStrongSpatialTypes="false" xmlns:annotation="http://schemas.microsoft.com/ado/2009/02/edm/annotation" xmlns:customannotation="http://schemas.microsoft.com/ado/2013/11/edm/customannotation" xmlns="http://schemas.microsoft.com/ado/2009/11/edm">
        <EntityType Name="view_area">
          <Key>
            <PropertyRef Name="UserId" />
            <PropertyRef Name="RoleId" />
            <PropertyRef Name="username" />
            <PropertyRef Name="Credit" />
          </Key>
          <Property Name="col" Type="Int64" />
          <Property Name="UserId" Type="String" MaxLength="128" FixedLength="false" Unicode="true" Nullable="false" />
          <Property Name="RoleId" Type="String" MaxLength="128" FixedLength="false" Unicode="true" Nullable="false" />
          <Property Name="username" Type="String" MaxLength="32" FixedLength="false" Unicode="true" Nullable="false" />
          <Property Name="school" Type="String" MaxLength="32" FixedLength="false" Unicode="true" />
          <Property Name="firsttime" Type="DateTime" Precision="3" />
          <Property Name="Credit" Type="Int64" Nullable="false" />
          <Property Name="Province" Type="String" MaxLength="50" FixedLength="false" Unicode="true" />
          <Property Name="City" Type="String" MaxLength="50" FixedLength="false" Unicode="true" />
          <Property Name="Area" Type="String" MaxLength="50" FixedLength="false" Unicode="true" />
        </EntityType>
        <EntityType Name="view_teacher">
          <Key>
            <PropertyRef Name="UserId" />
            <PropertyRef Name="RoleId" />
            <PropertyRef Name="username" />
            <PropertyRef Name="Credit" />
          </Key>
          <Property Name="col" Type="Int64" />
          <Property Name="UserId" Type="String" MaxLength="128" FixedLength="false" Unicode="true" Nullable="false" />
          <Property Name="RoleId" Type="String" MaxLength="128" FixedLength="false" Unicode="true" Nullable="false" />
          <Property Name="username" Type="String" MaxLength="32" FixedLength="false" Unicode="true" Nullable="false" />
          <Property Name="school" Type="String" MaxLength="32" FixedLength="false" Unicode="true" />
          <Property Name="firsttime" Type="DateTime" Precision="3" />
          <Property Name="Province" Type="String" MaxLength="50" FixedLength="false" Unicode="true" />
          <Property Name="City" Type="String" MaxLength="50" FixedLength="false" Unicode="true" />
          <Property Name="Area" Type="String" MaxLength="50" FixedLength="false" Unicode="true" />
          <Property Name="Credit" Type="Int64" Nullable="false" />
        </EntityType>
        <EntityContainer Name="OnlineEDUEntities1" annotation:LazyLoadingEnabled="true">
          <EntitySet Name="view_area" EntityType="Self.view_area" />
          <EntitySet Name="view_teacher" EntityType="Self.view_teacher" />
        </EntityContainer>
      </Schema>
    </edmx:ConceptualModels>
    <!-- C-S mapping content -->
    <edmx:Mappings>
      <Mapping Space="C-S" xmlns="http://schemas.microsoft.com/ado/2009/11/mapping/cs">
        <EntityContainerMapping StorageEntityContainer="OnlineEDUModelStoreContainer" CdmEntityContainer="OnlineEDUEntities1">
          <EntitySetMapping Name="view_area">
            <EntityTypeMapping TypeName="OnlineEDUModel.view_area">
              <MappingFragment StoreEntitySet="view_area">
                <ScalarProperty Name="col" ColumnName="col" />
                <ScalarProperty Name="UserId" ColumnName="UserId" />
                <ScalarProperty Name="RoleId" ColumnName="RoleId" />
                <ScalarProperty Name="username" ColumnName="username" />
                <ScalarProperty Name="school" ColumnName="school" />
                <ScalarProperty Name="firsttime" ColumnName="firsttime" />
                <ScalarProperty Name="Credit" ColumnName="Credit" />
                <ScalarProperty Name="Province" ColumnName="Province" />
                <ScalarProperty Name="City" ColumnName="City" />
                <ScalarProperty Name="Area" ColumnName="Area" />
              </MappingFragment>
            </EntityTypeMapping>
          </EntitySetMapping>
          <EntitySetMapping Name="view_teacher">
            <EntityTypeMapping TypeName="OnlineEDUModel.view_teacher">
              <MappingFragment StoreEntitySet="view_teacher">
                <ScalarProperty Name="col" ColumnName="col" />
                <ScalarProperty Name="UserId" ColumnName="UserId" />
                <ScalarProperty Name="RoleId" ColumnName="RoleId" />
                <ScalarProperty Name="username" ColumnName="username" />
                <ScalarProperty Name="school" ColumnName="school" />
                <ScalarProperty Name="firsttime" ColumnName="firsttime" />
                <ScalarProperty Name="Province" ColumnName="Province" />
                <ScalarProperty Name="City" ColumnName="City" />
                <ScalarProperty Name="Area" ColumnName="Area" />
                <ScalarProperty Name="Credit" ColumnName="Credit" />
              </MappingFragment>
            </EntityTypeMapping>
          </EntitySetMapping>
        </EntityContainerMapping>
      </Mapping>
    </edmx:Mappings>
  </edmx:Runtime>
  <!-- EF Designer content (DO NOT EDIT MANUALLY BELOW HERE) -->
  <Designer xmlns="http://schemas.microsoft.com/ado/2009/11/edmx">
    <Connection>
      <DesignerInfoPropertySet>
        <DesignerProperty Name="MetadataArtifactProcessing" Value="EmbedInOutputAssembly" />
      </DesignerInfoPropertySet>
    </Connection>
    <Options>
      <DesignerInfoPropertySet>
        <DesignerProperty Name="ValidateOnBuild" Value="true" />
        <DesignerProperty Name="EnablePluralization" Value="false" />
        <DesignerProperty Name="IncludeForeignKeysInModel" Value="true" />
        <DesignerProperty Name="UseLegacyProvider" Value="false" />
        <DesignerProperty Name="CodeGenerationStrategy" Value="无" />
      </DesignerInfoPropertySet>
    </Options>
    <!-- Diagram content (shape and connector positions) -->
    <Diagrams></Diagrams>
  </Designer>
</edmx:Edmx>

将生成的这两个实体类拷贝出来

 

4.删除生成的edmx文件，将之前备份的代码更新下来

 

5.以xml的形式编辑以前的edmx文件，把刚才生成的xml节点放到相应的位置上。

6.将生成的实体类.cs（view_area.cs,view_teacher.cs）拷贝到model中

7.找到继承DbContext的类，添加下述代码