我有一个数据表,我正在尝试为列实现服务器端过滤。我允许多列字符串每列查询,并试图确定跨步所有过滤器的最佳方法。下面是表对象的示例,为简单起见,只有2个参数。
//table models from db
public class Parts
{
public string PartName { get; set; }
public virtual Series Series { get; set; }
}
public class Series
{
public string SeriesName { get; set; }
}
//This is what is passed in from the datatable filter query
public class PartsTable
{
public string PartName { get; set; }
public string SeriesName { get; set; }
}
public IEnumerable<Parts> PartsTableSearch(PartsTable table)
{
//Queries come in as comma separated string
var partNameList = table.PartName?.Split(',');
var seriesNameList = table.SeriesName?.Split(',');
//Gets and generates the list of Parts
var fullList = GetParts();
if (partNameList != null && partNameList.Length > 0)
{
foreach (var partName in partNameList)
{
fullList = fullList.Where(p => p.PartName.ToLower().Contains(name.ToLower()));
}
}
if (seriesNameList != null && seriesNameList.Length > 0)
{
foreach (var seriesName in seriesNameList)
{
fullList = fullList.Where(p => p.Series.SeriesName.ToLower().Contains(seriesName.ToLower()));
}
}
return fullList;
}
这对我想要的东西不起作用,因为对于每个参数(即PartName),我需要能够返回所有具有PartName的对象,该PartName包含partNameList中的搜索字符串,然后从该结果中过滤进一步在包含seriesNameList中的搜索字符串的SeriesNames上,然后返回结果集。但是,partNameList的查询可能是空白的,只能搜索seriesName,反之亦然。有什么建议?我觉得这是一个明显的答案,我只是忽略了,虽然我搜索过的任何其他东西只适用于单个查询过滤器。提前谢谢。
答案 0 :(得分:5)
这可以通过两种方式使用单个.Where
来完成:
使用.Contain()
将返回完全匹配:
public IEnumerable<Parts> PartsTableSearch(PartsTable table)
{
//Queries come in as comma separated string
var partNameList = table.PartName?.Split(',');
var seriesNameList = table.SeriesName?.Split(',');
//Gets and generates the list of Parts
var fullList = GetParts()
.Where(p => partNameList.Contains(p.PartName.ToLower())
|| seriesNameList.Contains(p.Series.SeriesName.ToLower()))
.ToList();
return fullList;
}
使用.Any()
将返回部分匹配:
public IEnumerable<Parts> PartsTableSearch(PartsTable table)
{
//Queries come in as comma separated string
var partNameList = table.PartName?.Split(',');
var seriesNameList = table.SeriesName?.Split(',');
//Gets and generates the list of Parts
var fullList = GetParts()
.Where(p => partNameList.Any(n => n.Contains(p.PartName.ToLower())))
|| seriesNameList.Any(n => n.Contains(p.Series.SeriesName.ToLower())))
.ToList();
return fullList;
}
答案 1 :(得分:0)
为LinqToSql做了这个。我被告知它不适用于Entity Framework。它应该与内存中的集合一起使用。
public static Expression<Func<T, bool>> OrTheseFiltersTogether<T>(
this IEnumerable<Expression<Func<T, bool>>> filters)
{
Expression<Func<T, bool>> firstFilter = filters.FirstOrDefault();
if (firstFilter == null)
{
Expression<Func<T, bool>> alwaysTrue = x => true;
return alwaysTrue;
}
var body = firstFilter.Body;
var param = firstFilter.Parameters.ToArray();
foreach (var nextFilter in filters.Skip(1))
{
var nextBody = Expression.Invoke(nextFilter, param);
body = Expression.OrElse(body, nextBody);
}
Expression<Func<T, bool>> result = Expression.Lambda<Func<T, bool>>(body, param);
return result;
}
这样称呼:
public IEnumerable<Parts> PartsTableSearch(PartsTable table)
{
var fullList = GetParts();
var filters = new List<Expression<Func<Part, bool>>>();
if (table.PartName != null)
{
var partNameList = table.PartName.ToLower().Split(',');
foreach (var partName in partNameList)
{
filters.Add(p => p.PartName.ToLower().Contains(partName));
}
}
if (table.SeriesName != null)
{
var seriesNameList = table.SeriesName.ToLower().Split(',');
foreach (var seriesName in seriesNameList)
{
filters.Add(p => p.Series.SeriesName.ToLower().Contains(seriesName));
}
}
Expression<Func<Part, bool>> filter = filters.OrTheseFiltersTogether();
return fullList.Where(filter);
}
答案 2 :(得分:0)
对于您从不同查询获得的每个结果集使用Yield return
。如果它为空则无关紧要,所有结果都将在IEnumerable<Parts>
中收集。
public IEnumerable<Parts> PartsTableSearch(PartsTable table)
{
//Queries come in as comma separated string
var partNameList = table.PartName?.Split(',');
var seriesNameList = table.SeriesName?.Split(',');
//Gets and generates the list of Parts
var fullList = GetParts();
if (partNameList != null && partNameList.Length > 0)
{
foreach (var partName in partNameList)
{
yield return fullList.Where(p => p.PartName.ToLower().Contains(name.ToLower()));
}
}
if (seriesNameList != null && seriesNameList.Length > 0)
{
foreach (var seriesName in seriesNameList)
{
yield return fullList.Where(p => p.Series.SeriesName.ToLower().Contains(seriesName.ToLower()));
}
}
yield return null;
}
答案 3 :(得分:0)
这就是我最终让它发挥作用的方式。
var fullList = GetParts();
if (partNameList != null && partNameList.Length > 0)
{
var tempList = new List<Parts>();
foreach (var partName in partNameList)
{
tempList.AddRange(fullList.Where(p => p.PartName.ToLower().Contains(partName.ToLower().Trim())));
}
fullList = tempList;
}
if (seriesNameList != null && seriesNameList.Length > 0)
{
var tempList = new List<Parts>();
foreach (var seriesName in seriesNameList)
{
tempList.AddRange(fullList.Where(p => p.Series.SeriesName.ToLower().Contains(seriesName.ToLower().Trim())).ToList());
}
fullList = tempList;
}
return fullList.ToList();