private Expression GetExpression(ParameterExpression param, ConditionItem item)
{
//属性表达式
LambdaExpression exp = GetPropertyLambdaExpression(item, param);
//如果有特殊类型处理，则进行处理，暂时不关注
foreach (var provider in TransformProviders)
{
if (provider.Match(item, exp.Body.Type))
{
return(GetGroupExpression(param, provider.Transform(item, exp.Body.Type), Expression.AndAlso));
}
}
//常量表达式
var constant = ChangeTypeToExpression(item, exp.Body.Type);
//以判断符或方法连接
return(ExpressionDict[item.Method](exp.Body, constant));
}
private static void AddSearchItem(QueryModel model, string key, string val)
{
string field = "", prefix = "", orGroup = "", method = "";
var keywords = key.Split(']', ')', '}');
//将Html中的name分割为我们想要的几个部分
foreach (var keyword in keywords)
{
if (Char.IsLetterOrDigit(keyword[0]))
{
field = keyword;
}
var last = keyword.Substring(1);
if (keyword[0] == '(')
{
prefix = last;
}
if (keyword[0] == '[')
{
method = last;
}
if (keyword[0] == '{')
{
orGroup = last;
}
}
if (string.IsNullOrEmpty(method))
{
return;
}
if (!string.IsNullOrEmpty(field))
{
var item = new ConditionItem
{
Field = field,
Value = val.Trim(),
Prefix = prefix,
OrGroup = orGroup,
Method = (QueryMethod)Enum.Parse(typeof(QueryMethod), method)
};
model.Items.Add(item);
}
}
private LambdaExpression GetPropertyLambdaExpression(ConditionItem item, ParameterExpression param)
{
//获取每级属性如c.Users.Proiles.UserId
var props = item.Field.Split('.');
Expression propertyAccess = param;
var typeOfProp = typeof(T);
int i = 0;
do
{
PropertyInfo property = typeOfProp.GetProperty(props[i]);
if (property == null)
{
return(null);
}
typeOfProp = property.PropertyType;
propertyAccess = Expression.MakeMemberAccess(propertyAccess, property);
i++;
} while (i < props.Length);
return(Expression.Lambda(propertyAccess, param));
}
