public ISQLJoin LeftJoin <TJoin, TEntityOther>(Expression <Func <TJoin, TEntityOther, bool> > join)
{
SQLJoin sqlJoin = new SQLJoin(Sql, join, JoinType.LeftJoin);
sqlJoin.Type = typeof(TJoin);
sqlJoin.Mapper = EntityMapper.GetMapper <TJoin>();
Sql.Joins = new List <ISQLJoin>()
{
sqlJoin
};
return(sqlJoin);
}
public TEntity GetSingle <TEntity>(object keyValue)
{
var sql = new SQL();
var p = Expression.Parameter(typeof(TEntity), "p");
var mi = typeof(TEntity).GetMembers().Where(r => r.Name == EntityMapper.GetMapper <TEntity>().GetPrimaryKeys()[0]).FirstOrDefault();
var left = Expression.MakeMemberAccess(p, mi);
var right = Expression.Constant(keyValue);
var equal = Expression.Equal(left, right);
var lambda = Expression.Lambda <Func <TEntity, bool> >(equal, p);
sql = sql.Select <TEntity>().Where <TEntity>(lambda as Expression <Func <TEntity, bool> >).Sql;
return(Connection.QuerySingle <TEntity>(sql));
}
public SQLSelect(SQL sql, Type type)
{
Sql = sql;
Type = type;
Mapper = EntityMapper.GetMapper(type);
}
protected override Expression VisitMember(MemberExpression node)
{
object value = null;
Expression expression = searchMemberExpressionTree(node, node.Expression, out value);
if (expression.NodeType == ExpressionType.Parameter)
{
var param = node.Expression as ParameterExpression;
var mapper = EntityMapper.GetMapper(expression.Type);
string alias = param.Name;
if (_selectorCompilerStr != null)
{
// 编译select语句
if (!string.IsNullOrEmpty(Sql.Selector.Alias))
{
// 被As强制定义了别名
if (!string.IsNullOrEmpty(alias) && alias != Sql.Selector.Alias)
{
throw new Exception($"SQLSelect.ConfirmAlias Error: 别名\"{ Sql.Selector.Alias}\"不可用，因为当前的Select中已经定义了别名\"{alias}\"，请确保Select表达式\"{alias}=>\"中的名称与As(\"{Sql.Selector.Alias}\")中的名称一致");
}
}
else
{
// 没有被As强制定义别名
Sql.Selector.Alias = alias;
}
Sql.AliasCollection.Update(alias, Sql.Selector.Type);
_selectorCompilerStr?.Append($"{Sql.Selector.ComposeSelectKey(mapper.GetColumnName(node.Member.Name))} AS {node.Member.Name},");
}
if (_whereCompilerStr != null)
{
// 编译where语句
if (Sql.AliasCollection.Count == 0)
{
// 没有Alias，不显示
_whereCompilerStr.Append($"{mapper.GetColumnName(node.Member.Name)}");
}
else
{
if (Sql.AliasCollection.ContainsKey(alias))
{
_whereCompilerStr.Append($"{alias}.{mapper.GetColumnName(node.Member.Name)}");
}
else
{
throw new Exception($"SQLCompiler.VisitMember Error: 你正在有意使用别名\"{alias}\"，但在别名集合中没找到。尝试检查在Expression中使用的参数名是否在Select中使用过，或者是否在方法As()中定义过。'");
}
}
}
if (_orderCompilerStr != null)
{
// 编译order语句
if (Sql.AliasCollection.Count == 0)
{
// 没有Alias，不显示
_orderCompilerStr.Append($"{mapper.GetColumnName(node.Member.Name)}{(_compilingOrder.By == OrderBy.DESC ? " DESC" : "")},");
}
else
{
if (Sql.AliasCollection.ContainsKey(alias))
{
_orderCompilerStr.Append($"{alias}.{mapper.GetColumnName(node.Member.Name)}{(_compilingOrder.By == OrderBy.DESC ? " DESC" : "")},");
}
else
{
throw new Exception($"SQLCompiler.VisitMember Error: 你正在有意使用别名\"{alias}\"，但在别名集合中没找到。尝试检查在Expression中使用的参数名是否在Select中使用过，或者是否在方法As()中定义过。'");
}
}
}
if (_currentJoinCompilerStr != null)
{
// 编译Join语句
_currentJoinCompilerStr.Append($"{alias}.{mapper.GetColumnName(node.Member.Name)}");
}
}
else if (expression.NodeType == ExpressionType.Constant)
{
if (Sql.Parameters == null)
{
Sql.Parameters = new List <SQLParameter>();
}
var param = Sql.Parameters.AddParameter(value);
_whereCompilerStr?.Append(param.ParameterName);
_currentJoinCompilerStr?.Append(param.ParameterName);
}
return(node);
}
