C # - How to make multiple contains filters in a list of objects
I have a datasheet that I am trying to do server side filtering for columns. I am allowing multiple rows to query per column and am trying to figure out the best way to go through all filters. Below is an example of a table object with two parameters for simplicity.
//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;
}
This won't work for what I want, because for each parameter (i.e. PartName) I need to return all objects named PartName containing search strings in partNameList, and then from this result filter further by SeriesNames, which contain search strings in the rowNameList, then return a result set. However, the query for partNameList can be empty and search only in serialName, and vice versa. Any suggestions? I feel like this is an obvious answer that I just ignore, although everything I was looking for only works for one request filter. Thanks in advance.
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That's how I got the job.
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();
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This can be done with one in .Where
two ways:
Using.Contain()
which will return an exact match:
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;
}
Using.Any()
which will return a partial match:
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;
}
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Made for LinqToSql. I was told that it would not work with Entity Framework. It should work with an in-memory collection.
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;
}
Called like this:
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);
}
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Use Yield return
with every result set you get from different queries. It doesn't matter if it is null, all results will be collected in IEnumerable<Parts>
.
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;
}
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