// 把 Requests 表的全部数据备份到一个 XML 文件
public static async Task <NormalResult> BackupRequestsDatabaseAsync(
string strOutputFilename,
Delegate_displayText func_displayText,
CancellationToken token)
{
int count = 0;
using (var releaser = await _databaseLimit.EnterAsync())
{
XmlWriterSettings settings = new XmlWriterSettings();
settings.Async = true;
settings.Indent = true;
using (XmlWriter writer = XmlWriter.Create(strOutputFilename,
settings))
{
//writer.Formatting = System.Xml.Formatting.Indented;
//writer.Indentation = 4;
await writer.WriteStartDocumentAsync();
await writer.WriteStartElementAsync(null, "collection", null);
using (var context = new RequestContext())
using (var connection = context.Database.GetDbConnection())
{
await connection.OpenAsync();
using (var command = connection.CreateCommand())
{
command.CommandText = "SELECT * FROM [Requests]";
using (var reader = await command.ExecuteReaderAsync() /*as SqlDataReader*/)
{
while (await reader.ReadAsync())
{
if (token.IsCancellationRequested)
{
return new NormalResult
{
Value = -1,
ErrorInfo = "用户中断",
ErrorCode = "abort"
}
}
;
await writer.WriteStartElementAsync(null, "record", null);
// TODO: 记载全部字段名和类型，记载一次
for (int i = 0; i < reader.FieldCount; i++)
{
string name = reader.GetName(i);
Type type = reader.GetFieldType(i);
var value = reader[i].ToString();
if (string.IsNullOrEmpty(value) == false)
{
await writer.WriteStartElementAsync(null, "field", null);
await writer.WriteAttributeStringAsync(null, "name", null, name);
await writer.WriteStringAsync(value);
await writer.WriteEndElementAsync();
}
}
await writer.WriteEndElementAsync();
count++;
func_displayText?.Invoke($"已导出记录 {count}");
}
}
}
}
await writer.WriteEndElementAsync();
await writer.WriteEndDocumentAsync();
}
}
return(new NormalResult {
Value = count
});
}
// 从 XML 文件恢复全部数据到 Requests 表。
// 注意要处理好 XML 文件中字段比当前表定义的字段多或者少的情况，和字段改名的情况
public static async Task <NormalResult> RestoreRequestsDatabaseAsync(
string strInputFileName,
Delegate_displayText func_displayText,
CancellationToken token)
{
int count = 0;
using (var releaser = await _databaseLimit.EnterAsync())
{
XmlReaderSettings settings = new XmlReaderSettings();
settings.Async = true;
using (XmlReader reader = XmlReader.Create(strInputFileName, settings))
{
// 定位到 collection 元素
while (true)
{
bool bRet = await reader.ReadAsync();
if (bRet == false)
{
return(new NormalResult
{
Value = -1,
ErrorInfo = "文件 " + strInputFileName + " 没有根元素"
});
}
if (reader.NodeType == XmlNodeType.Element)
{
break;
}
}
using (var context = new RequestContext())
using (var connection = context.Database.GetDbConnection())
{
context.Database.EnsureDeleted();
context.Database.EnsureCreated();
await connection.OpenAsync();
using (var command = connection.CreateCommand())
{
while (await reader.ReadAsync())
{
if (token.IsCancellationRequested)
{
return new NormalResult
{
Value = -1,
ErrorInfo = "用户中断",
ErrorCode = "abort"
}
}
;
if (reader.NodeType == XmlNodeType.Element)
{
string record_xml = await reader.ReadOuterXmlAsync();
XmlDocument dom = new XmlDocument();
dom.LoadXml(record_xml);
List <string> fields = new List <string>();
List <string> values = new List <string>();
command.Parameters.Clear();
var field_nodes = dom.DocumentElement.SelectNodes("field");
foreach (XmlElement field_node in field_nodes)
{
string name = field_node.GetAttribute("name");
string value = field_node.InnerText;
//if (name == "ID")
// value = "0";
fields.Add(name);
command.Parameters.Add(new Microsoft.Data.Sqlite.SqliteParameter(name, value));
values.Add($"@{name}");
}
//StringBuilder command = new StringBuilder();
//command.Append("INSERT INTO [Requests] ");
command.CommandText = $"INSERT INTO [Requests] ({StringUtil.MakePathList(fields)}) VALUES ({StringUtil.MakePathList(values)})";
await command.ExecuteNonQueryAsync();
count++;
func_displayText?.Invoke($"已导入记录 {count}");
}
}
}
}
}
}
return(new NormalResult {
Value = count
});
}
