/// <summary>
/// 追加列名
/// </summary>
/// <param name="ag">表别名</param>
/// <param name="node">列名表达式</param>
/// <returns>返回解析到的表别名</returns>
public string AppendMember(AliasGenerator ag, Expression node)
{
Expression expression = node;
LambdaExpression lambdaExpression = expression as LambdaExpression;
if (lambdaExpression != null)
{
expression = lambdaExpression.Body;
}
if (expression.CanEvaluate())
{
ConstantExpression c = expression.Evaluate();
string value = _constor.GetSqlValue(c.Value, _context);
_innerBuilder.Append(value);
return(value);
}
else
{
MemberExpression m = expression.ReduceUnary() as MemberExpression;
string alias = ag == null ? null : ag.GetTableAlias(m);
this.AppendMember(alias, m.Member, m.Expression != null ? m.Expression.Type : null);
return(alias);
}
}
/// <summary>
/// 访问表达式节点
/// </summary>
/// <param name="wheres">筛选表达式</param>
public override Expression Visit(List <DbExpression> wheres)
{
if (wheres != null && wheres.Count > 0)
{
_builder.AppendNewLine();
_builder.Append("WHERE ");
for (int index = 0; index < wheres.Count; index++)
{
DbExpression d = wheres[index];
var node = d.Expressions[0];
if (node.NodeType == ExpressionType.Lambda)
{
node = ((LambdaExpression)node).Body;
}
node = BooleanUnaryToBinary(node);
if (!(node is ConstantExpression))
{
base.Visit(node);
}
else
{
// 字符符动态SQL，解析参数
DbRawSql rawSql = (node as ConstantExpression).Value as DbRawSql;
object[] args = null;
if (rawSql.Parameters != null)
{
args = rawSql.Parameters.Select(x => _constor.GetSqlValue(x, _context)).ToArray();
}
string sql = rawSql.CommandText;
if (args != null && args.Length > 0)
{
sql = string.Format(sql, args);
}
_builder.Append(sql);
}
if (index < wheres.Count - 1)
{
_builder.Append(" AND ");
}
}
}
return(null);
}