public SQL_XML_IO_statuses DeleteLearningItem(LearningItem learningitem)
{
if (learningitem == null) return SQL_XML_IO_statuses.OtherError;
RefTree.Clear();
DBConnect dbconnect = new DBConnect();
dbconnect.Open();
//logging = true;
//FindAllReferences_("LearningItems",learningitem.id);
if(ViewModelLocator.Instance.AppSetting.CurrentLearningItem.id == learningitem.id)
{
ViewModelLocator.Instance.AppSetting.CurrentLearningItem = null;
}
EFDbContext.SaveChgs();
// Rules
schema.ClearRules();
schema.GetTableByName(AppSetting.TableName).DontProcessing = true;
schema.GetTableByName(Dictionary.TableName).DontProcessing = true;
schema.GetTableByName(Language.TableName).DontProcessing = true;
schema.GetTableByName(WordOfDictionary.TableName).DontProcessing = true;
// optimization for speed
DBConnect.Query query = new DBConnect.Query();
query.sql = SQLqueries.Delete_Update_Subtitle_Items_Words;
query.AddParameter("id", learningitem.id);
dbconnect.ExecuteSQL(query);
query.sql = SQLqueries.Delete_Subtitile_Items_Words;
query.AddParameter("id", learningitem.id);
dbconnect.ExecuteSQL(query);
query.sql = SQLqueries.Delete_Subtitle_Items;
query.AddParameter("id", learningitem.id);
dbconnect.ExecuteSQL(query);
PathList.Clear();
DeleteTable(dbconnect,"LearningItems",learningitem.id,true);
dbconnect.Close();
((IObjectContextAdapter)ViewModelLocator.Instance.DataBase).ObjectContext.Detach(learningitem);
EFDbContext.SaveChgs();
return SQL_XML_IO_statuses.Ok;
}
public void DeleteTable(DBConnect dbconnect,string table_name,Guid id,bool remove,string path = "",int parent_key_number =0)
{
string sql;
if (path == "") path = table_name;
if (!PathList.Contains(path)) PathList.Add(path);
if (RefTreeContains(table_name, id)) return;
AddToRefList(table_name, id,path);
Dictionary<string,Ref> ForwardRefList = new Dictionary<string,Ref>();
// find forward references
var foreign_keys = schema.ForeignKey.Where((x) => x.Table_str == table_name && x.number != parent_key_number);
if(foreign_keys.Count() > 0)
{
foreach (ForeignKey key in foreign_keys) {
if (key.field.DontProcessing) continue;
if (key.PrimaryTable.DontProcessing) continue;
DBConnect.Query query = new DBConnect.Query();
query.sql = "SELECT [" + key.field_str + "] as id FROM [" + key.Table_str + "] where id=@id";
query.AddParameter("id", id);
Guid? res = dbconnect.GetGuid("SELECT [" + key.field_str + "] as id FROM [" + key.Table_str + "] where id='"+id.ToString()+"'");
if (res == null) continue;
Guid id_ = (Guid)res;
// is it a forward reference
if (!RefTreeContains(key.PrimaryTable_str, id_)){
ForwardRefList.Add(key.field_str,new Ref {tablename = key.PrimaryTable_str,guid = id_,number = key.number});
}
}
}
// Clearing the reference fields
if(ForwardRefList.Count > 0 && remove)
{
sql = "UPDATE ["+table_name+"] SET"+Environment.NewLine;
bool FirstElement = true;
foreach(var elm in ForwardRefList)
{
sql += (FirstElement ? "" : ",") + "[" + elm.Key + "]=null"+Environment.NewLine;
FirstElement = false;
}
sql += "WHERE id='"+id+"'";
dbconnect.ExecuteSQL(sql);
}
// delete objects by forward references
foreach(var elm in ForwardRefList)
{
DeleteTable(dbconnect,elm.Value.tablename, elm.Value.guid,remove,path + "->" +elm.Value.tablename,elm.Value.number);
}
// delete objects by backward references
foreign_keys = schema.ForeignKey.Where((x) => x.PrimaryTable_str == table_name && x.number != parent_key_number);
if(foreign_keys.Count() > 0)
{
foreach (ForeignKey key in foreign_keys) {
if (key.Table.DontProcessing) continue;
List<Guid> id_list = dbconnect.GetGuidList("SELECT id FROM [" + key.Table_str + "] where [" + key.field_str + "]='"+id.ToString()+"'");
string ids = "";
foreach (Guid id_ in id_list)
{
ids += (ids.Count() == 0 ? "":",")+id_;
if (!RefTreeContains(key.Table_str, id_))
{
DeleteTable(dbconnect,key.Table_str, id_,remove, path + "->" + key.Table_str, key.number);
}
}
}
}
if (remove)
{
dbconnect.ExecuteSQL("DELETE FROM ["+table_name+"] WHERE id='"+id.ToString()+"'");
}
}