/// <summary>
/// 解析非表达式,生成sql条件表达式节点及其附属的sql参数
/// </summary>
/// <param name="parameterExpression">Lambda表达式的参数</param>
/// <param name="bodyExpression">Lambda表达式的主体(或主体的一部分)</param>
/// <param name="parameterNames">记录不允许重复的sql参数名称</param>
/// <returns>sql条件表达式节点及其附属的sql参数</returns>
public override KeyValuePair <INodeBuilder, IDbDataParameter[]> Visit(ParameterExpression parameterExpression, Expression bodyExpression, HashSet <string> parameterNames)
{
//获取一元表达式并检查该表达式是否满足解析条件
UnaryExpression unaryExpression = bodyExpression as UnaryExpression;
if (unaryExpression.Operand == null)
{
throw new Exception(string.Format("Unknow Expression:{0}", unaryExpression.ToString()));
}
switch (unaryExpression.Operand.NodeType)
{
case ExpressionType.Equal:
case ExpressionType.NotEqual:
case ExpressionType.Call:
break;
default:
throw new Exception(string.Format("Unknow Expression:{0}", unaryExpression.ToString()));
}
//获取sql语句模板
WhereVisitor whereVisitor = this._factory.GetVisitor(unaryExpression.Operand.NodeType);
KeyValuePair <INodeBuilder, IDbDataParameter[]> sqlBuilderPair = whereVisitor.Visit(parameterExpression, unaryExpression.Operand, parameterNames);
StringBuilder sqlTemplate = new StringBuilder();
sqlBuilderPair.Key.Build(sqlTemplate);
//替换sql语句模板中的操作符为相反类型的操作符(如LIKE 替换为NOT LIKE)
string baseSqlTemplate = sqlTemplate.ToString();
if (baseSqlTemplate.Contains("LIKE"))
{
sqlTemplate.Replace("LIKE", "NOT LIKE");
}
if (baseSqlTemplate.Contains(" = "))
{
sqlTemplate.Replace(" = ", " <> ");
}
if (baseSqlTemplate.Contains(" != "))
{
sqlTemplate.Replace(" != ", " = ");
}
if (baseSqlTemplate.Contains("IS NULL"))
{
sqlTemplate.Replace("IS NULL", "IS NOT NULL");
}
if (baseSqlTemplate.Contains("IS NOT NULL"))
{
sqlTemplate.Replace("IS NOT NULL", "IS NULL");
}
if (baseSqlTemplate.Contains("IN"))
{
sqlTemplate.Replace("IN", "NOT IN");
}
//获取sql表达式
INodeBuilder nodeBuilder = new NodeBuilder(SqlType.Where, sqlTemplate.ToString());
//返回sql表达式及其附属的sql参数集合
return(new KeyValuePair <INodeBuilder, IDbDataParameter[]>(nodeBuilder, sqlBuilderPair.Value));
}
/// <summary>
/// 解析查询条件表达式,生成sql条件表达式节点及其附属的sql参数
/// </summary>
/// <param name="parameterExpression">Lambda表达式的参数</param>
/// <param name="bodyExpression">Lambda表达式的主体(或主体的一部分)</param>
/// <param name="parameterNames">记录不允许重复的sql参数名称</param>
/// <returns>sql条件表达式节点及其附属的sql参数</returns>
public override KeyValuePair <INodeBuilder, IDbDataParameter[]> Visit(ParameterExpression parameterExpression, Expression bodyExpression, HashSet <string> parameterNames)
{
//获取二叉树表达式
BinaryExpression binaryExpression = bodyExpression as BinaryExpression;
//获取左sql表达式及其附属参数
WhereVisitor leftVisitor = this._factory.GetVisitor(binaryExpression.Left.NodeType);
KeyValuePair <INodeBuilder, IDbDataParameter[]> leftPair = leftVisitor.Visit(parameterExpression, binaryExpression.Left, parameterNames);
//获取右sql表达式及其附属参数
WhereVisitor rightVisitor = this._factory.GetVisitor(binaryExpression.Right.NodeType);
KeyValuePair <INodeBuilder, IDbDataParameter[]> rightPair = rightVisitor.Visit(parameterExpression, binaryExpression.Right, parameterNames);
//获取最终的sql条件表达式节点
INodeBuilder nodeBuilder = new BinaryBuilder()
{
LeftBuilder = leftPair.Key,
NodeType = binaryExpression.NodeType,
RightBuilder = rightPair.Key
};
//获取其附属参数
IDbDataParameter[] sqlParameters = leftPair.Value.Concat(rightPair.Value).ToArray();
//返回最终的sql表达式及其附属参数
return(new KeyValuePair <INodeBuilder, IDbDataParameter[]>(nodeBuilder, sqlParameters));
}