Metadata file not found

错误    3    正在编译转换: 未能找到元数据文件“F:Program Files (x86)Microsoft Visual Studio 12.0Common7Tools..IDEMicrosoft.Data.Entity.Design.DatabaseGeneration.dll”    E:Program Files (x86)Microsoft Visual Studio 12.0Common7IDEExtensionsMicrosoftEntity Framework ToolsDBGenSSDLToSQL10.tt    1    1    杂项文件

原错误信息：

纠结了一半天，总算在 stackoverflow 找到了答案，

http://stackoverflow.com/questions/19664833/metadata-file-not-found-data-entity-model#

（没读懂英文的可以看我下面的分析）

问题简单分析，看下创建 EF 生成模型时候产生的 SSDLToSql10.tt（这是用于 Code First 模式下生成的一个模板文件，主要是用来生成一个 DLL SQL SCRIPT [此处没深入了解，如有不妥请指教]）

<# 
//---------------------------------------------------------------------
// <copyright file="SsdlToSql10.tt" company="Microsoft">
//      Copyright (c) Microsoft Corporation.  All rights reserved.
// </copyright>
//---------------------------------------------------------------------
// This T4 template generates T-SQL from an instance of 
// System.Data.Metadata.Edm.StoreItemCollection, an object representation
// of the SSDL. This T-SQL is compatible with SQL 2012, 2008, 2005, CE, and Azure databases.
//---------------------------------------------------------------------
// Note: We will resolve all paths in assembly directives at runtime, taking 
// macros and environment variables into account (e.g. $(ProjectDir), %VS120COMNTOOLS% etc.)
#>
<#@ assembly name="System.Core" #>
<#@ assembly name="%VS120COMNTOOLS%..IDEMicrosoft.Data.Entity.Design.DatabaseGeneration.dll"#>
<#@ assembly name="%VS120COMNTOOLS%..IDEEntityFramework.dll"#>
<#@ assembly name="%VS120COMNTOOLS%..IDEEntityFramework.SqlServer.dll" #>
<#@ assembly name="%VS120COMNTOOLS%..IDEEntityFramework.SqlServerCompact.dll" #>
<#@ import namespace="System.Linq" #>
<#@ import namespace="System.Text" #>
<#@ import namespace="System.Collections.Generic" #>
<#@ import namespace="System.Data.Entity" #>
<#@ import namespace="System.Data.Entity.Core.Metadata.Edm" #>
<#@ import namespace="Microsoft.Data.Entity.Design.DatabaseGeneration" #>
<#@ import namespace="System.Runtime.Remoting.Messaging" #>
<#@ import namespace="System.Text.RegularExpressions" #>
<#@ template language="C#" debug="true" hostspecific="true" #>
<#@ include file="GenerateTSQL.Utility.ttinclude"#>
<#@ output extension = ".sql" #>
<#

// +++++++++++++++++++++++++++++++++++++++++++++++++
// Setup for the template (initializing variables, etc.)
// +++++++++++++++++++++++++++++++++++++++++++++++++

    string databaseName = this.GetInput<string>(EdmParameterBag.ParameterName.DatabaseName.ToString());
    string edmxPath = this.GetInput<string>(EdmParameterBag.ParameterName.EdmxPath.ToString());
    Version targetVersion = this.GetInput<Version>(EdmParameterBag.ParameterName.TargetVersion.ToString());

    DbConfiguration.SetConfiguration(new TemplateDbConfiguration());

    if (false == InitializeAndValidateExistingStore()) 
    {
#>
-- Warning: There were errors validating the existing SSDL. Drop statements
-- will not be generated.
<#
    }
#>
-- --------------------------------------------------
<#
    if (this.IsSQLCE) {
#>
-- Entity Designer DDL Script for SQL Server Compact Edition
<#
    } else {
#>
-- Entity Designer DDL Script for SQL Server 2005, 2008, 2012 and Azure
<#
    }
#>
-- --------------------------------------------------
-- Date Created: <#=DateTime.Now#>
<#
    if (!String.IsNullOrEmpty(edmxPath))
    {
#>
-- Generated from EDMX file: <#=Id(edmxPath)#>
<#
    }
#>
-- --------------------------------------------------

<#  if (!this.IsSQLCE) 
    { 
#>
SET QUOTED_IDENTIFIER OFF;
GO
<#  if (!String.IsNullOrEmpty(databaseName))
    {
#>
USE [<#=Id(databaseName)#>];
GO
<#
    }
    foreach (string unescapedSchemaName in (from es in Store.GetAllEntitySets() select es.GetSchemaName()).Distinct())
    {
#>
IF SCHEMA_ID(N'<#=Lit(unescapedSchemaName)#>') IS NULL EXECUTE(N'CREATE SCHEMA [<#=Id(unescapedSchemaName)#>]');
<#
    }
#>
GO
<#  } #>

-- --------------------------------------------------
-- Dropping existing FOREIGN KEY constraints
<#  if (this.IsSQLCE)
    {
#>
-- NOTE: if the constraint does not exist, an ignorable error will be reported.
<#  } #>
-- --------------------------------------------------

<#
    foreach (AssociationSet associationSet in ExistingStore.GetAllAssociationSets())
    {
        ReferentialConstraint constraint = associationSet.ElementType.ReferentialConstraints.Single();
        string constraintName = Id(WriteFKConstraintName(constraint));
        AssociationSetEnd dependentSetEnd = associationSet.AssociationSetEnds.Where(ase => ase.CorrespondingAssociationEndMember == constraint.ToRole).Single();
        string schemaName = Id(dependentSetEnd.EntitySet.GetSchemaName());
        string dependentTableName = Id(dependentSetEnd.EntitySet.GetTableName());
        
        if (!this.IsSQLCE)
        {
#>
IF OBJECT_ID(N'[<#=Lit(schemaName)#>].[<#=Lit(constraintName)#>]', 'F') IS NOT NULL
<#      } #>
    ALTER TABLE <# if (!IsSQLCE) {#>[<#=schemaName#>].<#}#>[<#=dependentTableName#>] DROP CONSTRAINT [<#=constraintName#>];
GO
<#
    }
#>

-- --------------------------------------------------
-- Dropping existing tables
<#  if (this.IsSQLCE)
    {
#>
-- NOTE: if the table does not exist, an ignorable error will be reported.
<#  } #>
-- --------------------------------------------------

<#
    foreach (EntitySet entitySet in ExistingStore.GetAllEntitySets())
    { 
        string schemaName = Id(entitySet.GetSchemaName());
        string tableName = Id(entitySet.GetTableName());
        
        if (!this.IsSQLCE)
        {
#>
IF OBJECT_ID(N'[<#=Lit(schemaName)#>].[<#=Lit(tableName)#>]', 'U') IS NOT NULL
<#      } #>
    DROP TABLE <# if (!IsSQLCE) {#>[<#=schemaName#>].<#}#>[<#=tableName#>];
GO
<#
    }
#>

-- --------------------------------------------------
-- Creating all tables
-- --------------------------------------------------

<#
    foreach (EntitySet entitySet in Store.GetAllEntitySets())
    {
        string schemaName = Id(entitySet.GetSchemaName());
        string tableName = Id(entitySet.GetTableName());
#>
-- Creating table '<#=tableName#>'
CREATE TABLE <# if (!IsSQLCE) {#>[<#=schemaName#>].<#}#>[<#=tableName#>] (
<#
        for (int p = 0; p < entitySet.ElementType.Properties.Count; p++)
        {
            EdmProperty prop = entitySet.ElementType.Properties[p];
#>
    [<#=Id(prop.Name)#>] <#=prop.ToStoreType()#> <#=WriteIdentity(prop, targetVersion)#> <#=WriteNullable(prop.Nullable)#><#=(p < entitySet.ElementType.Properties.Count - 1) ? "," : ""#>
<#
        }
#>
);
GO

<# 
    } 
#>
-- --------------------------------------------------
-- Creating all PRIMARY KEY constraints
-- --------------------------------------------------

<#
    foreach (EntitySet entitySet in Store.GetAllEntitySets())
    {
        string schemaName = Id(entitySet.GetSchemaName());
        string tableName = Id(entitySet.GetTableName());
#>
-- Creating primary key on <#=WriteColumns(entitySet.ElementType.GetKeyProperties(), ',')#> in table '<#=tableName#>'
ALTER TABLE <# if (!IsSQLCE) {#>[<#=schemaName#>].<#}#>[<#=tableName#>]
ADD CONSTRAINT [PK_<#=tableName#>]
    PRIMARY KEY <# if (!IsSQLCE) {#>CLUSTERED <#}#>(<#=WriteColumns(entitySet.ElementType.GetKeyProperties(), ',')#> <# if (!IsSQLCE) {#>ASC<#}#>);
GO

<#
    }
#>
-- --------------------------------------------------
-- Creating all FOREIGN KEY constraints
-- --------------------------------------------------

<#
    foreach (AssociationSet associationSet in Store.GetAllAssociationSets())
    {
        ReferentialConstraint constraint = associationSet.ElementType.ReferentialConstraints.Single();
        AssociationSetEnd dependentSetEnd = associationSet.AssociationSetEnds.Where(ase => ase.CorrespondingAssociationEndMember == constraint.ToRole).Single();
        AssociationSetEnd principalSetEnd = associationSet.AssociationSetEnds.Where(ase => ase.CorrespondingAssociationEndMember == constraint.FromRole).Single();
        string schemaName = Id(dependentSetEnd.EntitySet.GetSchemaName());
        string dependentTableName = Id(dependentSetEnd.EntitySet.GetTableName());
        string principalTableName = Id(principalSetEnd.EntitySet.GetTableName());
#>
-- Creating foreign key on <#=WriteColumns(constraint.ToProperties, ',')#> in table '<#=dependentTableName#>'
ALTER TABLE <#if (!IsSQLCE) {#>[<#=schemaName#>].<#}#>[<#=dependentTableName#>]
ADD CONSTRAINT [<#=WriteFKConstraintName(constraint)#>]
    FOREIGN KEY (<#=WriteColumns(constraint.ToProperties, ',')#>)
    REFERENCES <# if (!IsSQLCE) {#>[<#=schemaName#>].<#}#>[<#=principalTableName#>]
        (<#=WriteColumns(constraint.FromProperties, ',')#>)
    ON DELETE <#=GetDeleteAction(constraint)#> ON UPDATE NO ACTION;
<#      
        // if the foreign keys are part of the primary key on the dependent end, then we should not add a constraint.
        if (!dependentSetEnd.EntitySet.ElementType.GetKeyProperties().Take(constraint.ToProperties.Count()).OrderBy(r => r.Name).SequenceEqual(constraint.ToProperties.OrderBy(r => r.Name)))
        {
#>

-- Creating non-clustered index for FOREIGN KEY '<#=WriteFKConstraintName(constraint)#>'
CREATE INDEX [IX_<#=WriteFKConstraintName(constraint)#>]
ON <#if (!IsSQLCE) {#>[<#=schemaName#>].<#}#>[<#=dependentTableName#>]
    (<#=WriteColumns(constraint.ToProperties, ',')#>);
<#      
        }
#>
GO

<#
    }
#>
-- --------------------------------------------------
-- Script has ended
-- --------------------------------------------------

这里面就可以看到它引用了这几个程序集

<#@ assembly name="System.Core" #>
<#@ assembly name="%VS120COMNTOOLS%..IDEMicrosoft.Data.Entity.Design.DatabaseGeneration.dll"#>
<#@ assembly name="%VS120COMNTOOLS%..IDEEntityFramework.dll"#>
<#@ assembly name="%VS120COMNTOOLS%..IDEEntityFramework.SqlServer.dll" #>
<#@ assembly name="%VS120COMNTOOLS%..IDEEntityFramework.SqlServerCompact.dll" #>

索性我发现这几个程序集确实没在编译报错的路径中，我直接 copy 粘贴到了指定的目录下甚至还在编译器中引用，编译依旧如此。有点棘手！

最后看了老外的分析，说是 visual studio 安装的环境变量值路径不对，后来才一愣发现真是这个问题

控制面板->系统->高级系统设置->高级->环境变量

最终才明白原来编译的路径依据是根据环境变量来的，真是图样图森破