/// <summary>
/// Gets a JOIN QueryPredicate based on a LINQ Expression with two parameters.
/// </summary>
/// <returns>The JOIN QueryPredicate.</returns>
/// <param name="expression">The expression to be translated.</param>
/// <typeparam name="T1">Left entity involved in the JOIN (it must inherit from IEntity class).</typeparam>
/// <typeparam name="T2">Right entity involved in the JOIN (it must inherit from IEntity class).</typeparam>
public void Join <T1, T2>(JoinType joinType, Expression <Func <T1, T2, bool> > expression, EntitySet <T1> entitySet1, EntitySet <T2> entitySet2) where T1 : class, IEntity, new() where T2 : class, IEntity, new()
{
T1 entity1 = new T1();
T2 entity2 = new T2();
string parameter1 = expression.Parameters[0].Name;
string parameter2 = expression.Parameters[1].Name;
if (joinType != JoinType.Inner && Parameters.Contains(parameter2))
{
throw new Exception($"Alias '" + parameter2 + " already used within a " + GetJoinType(JoinTypeDictionary[parameter2]) + "' operator. No further use with RIGHT JOIN or LEFT JOIN is allowed.");
}
SQLPredicate queryPredicate = QueryTranslator.Translate(Evaluator.PartialEval(expression), i);
i += queryPredicate.Parameters.Count;
AddParameter(parameter1, entity1, typeof(EntitySet <T1>), typeof(T1), entitySet1, joinType);
AddParameter(parameter2, entity2, typeof(EntitySet <T2>), typeof(T2), entitySet2, joinType);
if (AddingOrder[parameter1] > AddingOrder[parameter2])
{
QueryDictionary[parameter1].Add(queryPredicate);
}
else
{
QueryDictionary[parameter2].Add(queryPredicate);
}
}
/// <summary>
/// Uses QueryTranslator to translate a LINQ Expression to a SQL query.
/// </summary>
/// <returns>The sql query.</returns>
/// <param name="expression">The LINQ Expression to be translated.</param>
/// <typeparam name="T">The 1st type parameter.</typeparam>
private SQLPredicate Translate(Expression expression, bool ignoreAliases = false)
{
ISQLTranslator sql = SQLTranslatorFactory.GetTranslator(DbType);
SQLPredicate pred = sql.Translate(Evaluator.PartialEval(expression), 0, ignoreAliases);
return(pred);
}
/// <summary>
/// Uses QueryTranslator to translate a LINQ Expression to a SQL query.
/// </summary>
/// <returns>The sql query.</returns>
/// <param name="expression">The LINQ Expression to be translated.</param>
/// <typeparam name="T">The 1st type parameter.</typeparam>
private SQLPredicate Translate(Expression expression)
{
ISQLTranslator sql = SQLTranslatorFactory.GetTranslator(DbType);
SQLPredicate pred = sql.Translate(Evaluator.PartialEval(expression));
return(pred);
}
