Ajouter des éléments à une liste par reflection
Bonjour,
j'essai d'initialiser une instance de classe à l'aide de la reflection.
Pour cela j'ai pris soin de nommer et typer les propriété de la classe du même noms et types que les colonnes de la table.
Cela fonctionne parfaitement pour les types simples. Par contre j'ai du mal à populer les listes.
voici mon code:
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public class Calendar : Root
{
protected string _CalendarName;
// Properties
public string CalendarName { get { return _CalendarName; } }
public List<string> SubCal { get; set; }
public List<DateTime> Holidays { get; set; }
// Constructor
public Calendar(string name)
{
Dictionary<string, Object> keys = new Dictionary<string, Object>();
keys.Add("CalendarName", name);
loadFromDB("subcalendar", keys);
loadFromDB("calendarview", keys);
}
} |
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public class Root
{
private string _connectionString;
public Root()
{
string bdd = ConfigurationManager.AppSettings["BDD"];
_connectionString = ConfigurationManager.ConnectionStrings[bdd].ConnectionString;
}
private string buildClause(KeyValuePair<string, Object> kvp)
{
PropertyInfo prop = this.GetType().GetProperty(kvp.Key);
string clause = "";
string typeName = this.GetType().GetProperty(kvp.Key).PropertyType.Name;
switch (typeName)
{
case "String":
clause = kvp.Key + " = '" + Convert.ToString(kvp.Value) + "'";
break;
case "Boolean":
clause = kvp.Key + " = " + (Convert.ToBoolean(kvp.Value) ? "true" : "false");
break;
case "DateTime":
clause = kvp.Key + " = '" + Convert.ToDateTime(kvp.Value).ToString("yyyy-MM-dd") + "'";
break;
default:
throw new UnknownTypeException("Unknown type : " + typeName);
}
return clause;
}
private object getValue(MySqlDataReader reader, Type type, int col)
{
switch (type.Name)
{
case "String":
return reader.GetString(col);
case "DateTime":
return reader.GetDateTime(col);
case "Boolean":
return reader.GetBoolean(col);
default:
throw new UnknownTypeException("Unknown type : " + type.Name);
}
}
public void loadFromDB(string tableName, Dictionary<string, Object> keys)
{
// Build SQL request from parameters
string sql = "select * from " + tableName;
bool first = true;
foreach (KeyValuePair<string, Object> kvp in keys)
{
sql += (first ? " where " : " and ") + buildClause(kvp);
first = false;
}
// Execute sql request
MySqlConnection myConnection = new MySqlConnection(_connectionString);
MySqlCommand myCommand = myCommand = new MySqlCommand(sql, myConnection);
myConnection.Open();
MySqlDataReader reader = myCommand.ExecuteReader();
// Parse result
if (reader.HasRows)
{
// Here we know there is at least one row
// First get the objects property
PropertyInfo[] props = this.GetType().GetProperties();
// The dictionnary will store the corresponding column number in the reader result
Dictionary<PropertyInfo, int> columns = new Dictionary<PropertyInfo, int>();
// Parse the properties to get the corresponding column number
foreach (PropertyInfo prop in props)
{
try
{
// Store the pair in the dictionnary
columns.Add(prop, reader.GetOrdinal(prop.Name));
}
catch (IndexOutOfRangeException e)
{
// current property does exist as column is this table
// ignore this error
}
}
// For each result row
while (reader.Read())
{
// Parse the properties to fetch them from reader data
foreach (KeyValuePair<PropertyInfo, int> column in columns)
{
// get the property type
Type type = column.Key.PropertyType;
// Check if it is a List
if (type.IsGenericType && type.GetGenericTypeDefinition() == typeof(List<>))
{
// Get the list item type
Type itemType = type.GetGenericArguments()[0];
// Get the list to add the value
var col = column.Key.GetValue(this, null) as IList;
if (col != null) // --> col is always null
col.Add(getValue(reader, itemType, column.Value));
else
throw new InvalidOperationException("Not a list");
}
else
{
// If not just fetch the property or the corresponding field
if (column.Key.CanWrite)
column.Key.SetValue(this, getValue(reader, type, column.Value), null);
else
this.GetType().GetField("_" + column.Key.Name, BindingFlags.NonPublic | BindingFlags.Instance).SetValue(this, getValue(reader, type, column.Value));
}
}
}
}
}
}
} |
et enfin le contenu des tables pour un calendrier
subcalendar:
CalendarName SubCal
000 London
000 New-York
calendarview:
CalendarName Holidays
000 05/11/2013
000 04/07/2013
Malheureusement, dans le la classe Root, je n'arrive pas à récupérer l'instance de List pour y ajouter un élément. J'obtiens toujours un pointeur null.
une idée pour me dépanner ?
