I am a bit new to Dapper and am trying to find a clean way to pass a filter parameter to SQL Query for a collection with more than one property.
My collection looks like this:
[{
Prop1: 'A Value 1',
Prop2: 'B Value 1'
},
{
Prop1: 'A Value 2',
Prop2: 'B Value 2'
}]
Which should result in a SQL Query looking something like this:
select *
from SampleTable
where
([ColumnA]='A Value 1' and [ColumnB]='B Value 1')
or ([ColumnA]='A Value 2' and [ColumnB]='B Value 2')
Note: Something like whats shown below will not work because the two properties PropA and PropB need to filter together.
string query = @"select *
from SampleTable
where [ColumnA] in (@PropA_Value)
and [ColumnB] in (@PropB_Value)"
con.Query<T>(query, new{PropA_Value = PropA,PropB_Value = PropB}).AsList();
You can generate filter strings dynamically using the following helper class:
public static class DapperHelper
{
private const string SingleTupleFormat = " [{0}] = '{1}' {2}";
private const string AndString = "AND";
private const string OrString = "OR";
private static string ToSqlTuple(List<Dictionary<string, string>> filters)
{
string filterParam = string.Empty;
foreach (var filter in filters)
{
//Construct single tuple
string tuple = filter.ToList().Aggregate(string.Empty,
(current, pair) => current + String.Format(SingleTupleFormat, pair.Key, pair.Value, AndString));
//Concatenate tuples by OR, string.Format to combine the different filters
filterParam += string.Format(" ({0}) {1}", tuple.TrimEnd(AndString), OrString);
}
return filterParam.TrimEnd(OrString);
}
public static string TrimEnd(this string source, string value)
{
if (!source.EndsWith(value))
return source;
return source.Remove(source.LastIndexOf(value));
}
}
Usage:
string query = @"select *
from SampleTable
where @where";
List<Dictionary<string, string>> filters = new List<Dictionary<string, string>>() {
new Dictionary<string, string>(){{"ColumnA", "A Value 1"},{"ColumnB", "A Value 2"}},
new Dictionary<string, string>(){{"ColumnA", "B Value 1"},{"ColumnB", "B Value 2"}}
};
var tuple = DapperHelper.ToSqlTuple(filters);
query = query.Replace("@where", string.IsNullOrEmpty(tuple) ? "1=1" : tuple); //Use 1=1 if tuple is empty or null
var data = con.Query<T>(query).AsList();
Query string looks like:
select *
from SampleTable
where ( [ColumnA] = 'A Value 1' AND [ColumnB] = 'A Value 2' )
OR ( [ColumnA] = 'B Value 1' AND [ColumnB] = 'B Value 2' )