情况：我做了一个应用程序更新程序。问题是更新后的应用程序使用的数据库可能不同。
我已经搜索了一个 .dll，它可以制作备份转储并为不同的数据库类型轻松恢复该转储。但遗憾的是没有可用的。
我的第一个想法是为每个 DatabaseType 制作一个用例，并使用 config.txt 文件指定的正确用例。但我的老板不喜欢这种解决方案。因此，我尝试查看是否可以 NHibernate（也用于发送更新文件）来进行数据库备份。可悲的是，虽然这是可能的，但它是不可行的。因为这会产生过多的开销。我还查看了 Rhino.ETL，但遗憾的是没有足够的文档供我使用。
所以我想问一下是否有人知道其他可能有用的方法。还是我辞职是为了违背我老板的意愿并使用每个用例的方法？
我使用 NHibernate 进行备份和恢复。导出和导入中实体的顺序很重要
ExportData(config, config.BuildSessionFactory(), dataFile, config.ClassMappings.Select(m => m.EntityName));
public void ExportData(Configuration config, ISessionFactory factory, string dataFile, IEnumerable<string> entitiesToExport)
{
File.Delete(dataFile);
using (var zip = new ZipFile(dataFile) { CompressionMethod = CompressionMethod.Deflate, CompressionLevel = CompressionLevel.BestCompression })
using (var session = factory.OpenStatelessSession())
using (var tx = session.BeginTransaction())
{
foreach (var name in entitiesToExport)
{
// copy for closure
var entityName = name;
zip.AddEntry(entityName + ".csv", (tablename, outstream) =>
{
using (var writer = new StreamWriter(outstream))
{
// mapping der Klasse
var entityMap = config.GetClassMapping(entityName);
// only properties, no Collections (toMany)
var properties = entityMap.PropertyClosureIterator.Where(prop => prop.ColumnSpan > 0).ToArray();
// write csv(tsv) header
writer.WriteLine(string.Join(SEPERATOR, ToPropertyNames(properties)));
var classMetaData = factory.GetClassMetadata(entityName);
const int pagesize = 10000;
int page = 0;
IList<object> objects;
do
{
objects = session.CreateCriteria(entityName)
.SetFirstResult(page * pagesize)
.SetMaxResults(pagesize)
.AddOrder(Order.Asc(Projections.Id()))
.List<object>();
foreach (var obj in objects)
{
// get property values as string
var values = ToPropertyValues(factory, classMetaData, properties, string.Empty, obj).Select(Serialize);
writer.WriteLine(string.Join(SEPERATOR, values));
}
page++;
} while (objects.Count > 0);
}
});
}
zip.Save(dataFile);
}
}
并导入
public void ImportData(NHCfg.Configuration config, ISessionFactory factory, string dataFile)
{
using (var zip = new ZipFile(dataFile))
using (var session = factory.OpenSession())
using (var tx = session.BeginTransaction())
{
var filesAndMaps = from file in zip.EntryFileNames
join map in config.ClassMappings on Path.GetFileNameWithoutExtension(file) equals map.EntityName
select new { Filename = file, Entitymap = map };
foreach (var fileAndMap in filesAndMaps)
{
using (Stream stream = zip[fileAndMap.Filename].OpenReader())
using (StreamReader reader = new StreamReader(stream))
{
// mapping der Klasse
var classMetadata = factory.GetClassMetadata(fileAndMap.Entitymap.EntityName);
var propertyNames = reader.ReadLine().Split(SEPERATOR[0]).Select(str => str.EndsWith("_Id") ? str.Remove(str.Length - "_Id".Length) : str).ToArray();
// propertyNamen(/pfade) und typen aus dem mapping holen
List<string> names = new List<string>();
List<IType> itypes = new List<IType>();
names.AddRange(classMetadata.PropertyNames);
itypes.AddRange(classMetadata.PropertyTypes);
for (int index = names.Count - 1; index >= 0; index--)
{
var propertyType = itypes[index];
if (propertyType.IsComponentType)
{
var basename = names[index];
var componentType = (ComponentType)propertyType;
names.RemoveAt(index);
names.InsertRange(index, componentType.PropertyNames.Select(name => basename + "." + name));
itypes.RemoveAt(index);
itypes.InsertRange(index, componentType.Subtypes);
index += componentType.Subtypes.Length;
}
else if (propertyType.IsEntityType)
{
itypes[index] = factory.GetClassMetadata(((EntityType)propertyType).GetAssociatedEntityName()).IdentifierType;
}
}
// mit den namen aus der csv abgleichen um den index im array der namen und typen zu bestimmen
int[] indices = new int[propertyNames.Length];
for (int i = 0; i < indices.Length; i++)
{
indices[i] = names.IndexOf(propertyNames[i]);
}
object[] deserialisedValues = new object[itypes.Count];
object[] objectValues = new object[classMetadata.PropertyTypes.Length];
string line;
while ((line = reader.ReadLine()) != null)
{
string[] serialisedValues = line.Split(SEPERATOR[0]);
// Werte deserialisieren
for (int i = 0; i < serialisedValues.Length; i++)
{
// nur deserialisieren wenn es das property überhaupt noch gibt
if (indices[i] >= 0)
deserialisedValues[indices[i]] = Deserialize(serialisedValues[i], itypes[indices[i]].ReturnedClass);
}
int offset = 0;
for (int i = 0; i < objectValues.Length; i++)
{
var propertyType = classMetadata.PropertyTypes[i];
if (propertyType.IsComponentType)
{
objectValues[i] = ToComponentObject(deserialisedValues, ref offset, (ComponentType)propertyType, session);
}
else
{
objectValues[i] = (propertyType.IsEntityType && deserialisedValues[offset] != null) ?
session.Load(((ManyToOneType)propertyType).GetAssociatedEntityName(), deserialisedValues[offset]) :
deserialisedValues[offset];
offset++;
}
}
object entity = classMetadata.Instantiate(null, EntityMode.Poco);
classMetadata.SetPropertyValues(entity, objectValues, EntityMode.Poco);
session.Save(entity);
}
}
}
tx.Commit();
}
}
不存在的功能是供读者练习的
很好的答案 Firo，可以把方法“ToPropertyNames”、“ToPropertyValues”和“ToComponentObject”的代码吗？
我补充说要使用它，需要库DotNetZip