如何使用元数据加载委托创建 MetadataWorkspace? [英] How can I create a MetadataWorkspace using metadata loading delegates?
问题描述
我遵循了这个示例 在运行时更改架构名称 - 实体框架,我可以从 MetaDataWorkspace 创建一个新的 EntityConnection,然后我用它来构造具有不同架构的 DbContext,但是我收到编译器警告,说 RegisterItemCollection 方法已过时,并且使用接受元数据加载的构造函数构造 MetadataWorkspace代表."
I followed this example Changing schema name on runtime - Entity Framework where I can create a new EntityConnection from a MetaDataWorkspace that I then use to construct a DbContext with a different schema, but I get compiler warnings saying that RegisterItemCollection method is obsolete and to "Construct MetadataWorkspace using constructor that accepts metadata loading delegates."
我该怎么做?这是有效的代码,但为 RegsiterItemCollection 调用提供了 3 个警告.我很惊讶它的工作原理,因为警告说已过时而不仅仅是已弃用.
How do I do that? Here is the code that is working but gives the 3 warnings for the RegsiterItemCollection calls. I'm surprised it works since warning says obsolete not just deprecated.
public static EntityConnection CreateEntityConnection(string schema, string connString, string model)
{
XmlReader[] conceptualReader = new XmlReader[]
{
XmlReader.Create(
Assembly
.GetExecutingAssembly()
.GetManifestResourceStream(model + ".csdl")
)
};
XmlReader[] mappingReader = new XmlReader[]
{
XmlReader.Create(
Assembly
.GetExecutingAssembly()
.GetManifestResourceStream(model + ".msl")
)
};
var storageReader = XmlReader.Create(
Assembly
.GetExecutingAssembly()
.GetManifestResourceStream(model + ".ssdl")
);
//XNamespace storageNS = "http://schemas.microsoft.com/ado/2009/02/edm/ssdl"; // this would not work!!!
XNamespace storageNS = "http://schemas.microsoft.com/ado/2009/11/edm/ssdl";
var storageXml = XElement.Load(storageReader);
foreach (var entitySet in storageXml.Descendants(storageNS + "EntitySet"))
{
var schemaAttribute = entitySet.Attributes("Schema").FirstOrDefault();
if (schemaAttribute != null)
{
schemaAttribute.SetValue(schema);
}
}
storageXml.CreateReader();
StoreItemCollection storageCollection =
new StoreItemCollection(
new XmlReader[] { storageXml.CreateReader() }
);
EdmItemCollection conceptualCollection = new EdmItemCollection(conceptualReader);
StorageMappingItemCollection mappingCollection =
new StorageMappingItemCollection(
conceptualCollection, storageCollection, mappingReader
);
//var workspace2 = new MetadataWorkspace(conceptualCollection, storageCollection, mappingCollection);
var workspace = new MetadataWorkspace();
workspace.RegisterItemCollection(conceptualCollection);
workspace.RegisterItemCollection(storageCollection);
workspace.RegisterItemCollection(mappingCollection);
var connectionData = new EntityConnectionStringBuilder(connString);
var connection = DbProviderFactories
.GetFactory(connectionData.Provider)
.CreateConnection();
connection.ConnectionString = connectionData.ProviderConnectionString;
return new EntityConnection(workspace, connection);
}
推荐答案
我能够摆脱 3 条警告消息.基本上它希望您在 MetadataWorkspace 的构造函数中注册集合.
I was able to get rid of the 3 warning messages. Basically it wants you to register the collections in the constructor of the MetadataWorkspace.
MetadataWorkspace 有 3 种不同的重载,我选择使用需要为工作区元数据提供路径(字符串数组)的重载.为此,我将读者保存到临时文件并重新加载它们.
There are 3 different overloads for MetadataWorkspace, I chose to use the one which requires to to supply a path (array of strings) to the workspace metadata. To do this I saved readers to temp files and reloaded them.
这对我有用,没有任何警告.
This is working for me without any warnings.
public static EntityConnection CreateEntityConnection(string schema, string connString, string model) {
var conceptualReader = XmlReader.Create(Assembly.GetExecutingAssembly().GetManifestResourceStream(model + ".csdl"));
var mappingReader = XmlReader.Create(Assembly.GetExecutingAssembly().GetManifestResourceStream(model + ".msl"));
var storageReader = XmlReader.Create(Assembly.GetExecutingAssembly().GetManifestResourceStream(model + ".ssdl"));
XNamespace storageNS = "http://schemas.microsoft.com/ado/2009/11/edm/ssdl";
var storageXml = XElement.Load(storageReader);
var conceptualXml = XElement.Load(conceptualReader);
var mappingXml = XElement.Load(mappingReader);
foreach (var entitySet in storageXml.Descendants(storageNS + "EntitySet")) {
var schemaAttribute = entitySet.Attributes("Schema").FirstOrDefault();
if (schemaAttribute != null) {
schemaAttribute.SetValue(schema);
}
}
storageXml.Save("temp.ssdl");
conceptualXml.Save("temp.csdl");
mappingXml.Save("temp.msl");
MetadataWorkspace workspace = new MetadataWorkspace(new List<String>(){
@"temp.csdl",
@"temp.ssdl",
@"temp.msl"
}
, new List<Assembly>());
var connectionData = new EntityConnectionStringBuilder(connString);
var connection = DbProviderFactories.GetFactory(connectionData.Provider).CreateConnection();
connection.ConnectionString = connectionData.ProviderConnectionString;
return new EntityConnection(workspace, connection);
}
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