I have extended some functionality to a DataContext object (called "CodeLookupAccessDataContext") such that the object exposes some methods to return results of LINQ to SQL queries. Here are the methods I have defined:
public List<CompositeSIDMap> lookupCompositeSIDMap(int regionId, int marketId)
{
var sidGroupId = CompositeSIDGroupMaps.Where(x => x.RegionID.Equals(regionId) && x.MarketID.Equals(marketId))
.Select(x => x.CompositeSIDGroup);
IEnumerator<int> sidGroupIdEnum = sidGroupId.GetEnumerator();
if (sidGroupIdEnum.MoveNext())
return lookupCodeInfo<CompositeSIDMap, CompositeSIDMap>(x => x.CompositeSIDGroup.Equals(sidGroupIdEnum.Current), x => x);
else
return null;
}
private List<TResult> lookupCodeInfo<T, TResult>(Func<T, bool> compLambda, Func<T, TResult> selectLambda)
where T : class
{
System.Data.Linq.Table<T> dataTable = this.GetTable<T>();
var codeQueryResult = dataTable.Where(compLambda)
.Select(selectLambda);
List<TResult> codeList = new List<TResult>();
foreach (TResult row in codeQueryResult)
codeList.Add(row);
return codeList;
}
CompositeSIDGroupMap and CompositeSIDMap are both tables in our database that are represented as objects in my DataContext object. I wrote the following code to call these methods and display the T-SQL generated after calling these methods:
using (CodeLookupAccessDataContext codeLookup = new CodeLookupAccessDataContext())
{
codeLookup.Log = Console.Out;
List<CompositeSIDMap> compList = codeLookup.lookupCompositeSIDMap(5, 3);
}
I got the following results in my log after invoking this code:
SELECT [t0].[CompositeSIDGroup]
FROM [dbo].[CompositeSIDGroupMap] AS [t0]
WHERE ([t0].[RegionID] = @p0) AND ([t0].[MarketID] = @p1)
-- @p0: Input Int (Size = 0; Prec = 0; Scale = 0) [5]
-- @p1: Input Int (Size = 0; Prec = 0; Scale = 0) [3]
-- Context: SqlProvider(Sql2005) Model: AttributedMetaModel Build: 3.5.30729.1
SELECT [t0].[PK_CSM], [t0].[CompositeSIDGroup], [t0].[InputSID], [t0].[TargetSID], [t0].[StartOffset], [t0].[EndOffset], [t0].[Scale]
FROM [dbo].[CompositeSIDMap] AS [t0]
-- Context: SqlProvider(Sql2005) Model: AttributedMetaModel Build: 3.5.30729.1
The first T-SQL statement contains a where clause as specified and returns one column as expected. However, the second statement is missing a where clause and returns all columns, even though I did specify which rows I wanted to view and which columns were of interest. Why is the second T-SQL statement generated the way it is, and what should I do to ensure that I filter out the data according to specifications via the T-SQL?
Also note that I would prefer to keep lookupCodeInfo() and especially am interested in keeping it enabled to accept lambda functions for specifying which rows/columns to return.
