Specifying Returned Rows in LINQ2DataSet
I have a requirement to retrieve a separate subset of rows from a DataTable and thought LINQ2DataSets might be a useful and clean way to do this, however it seems that it is not possible to simply determine the return rows from a LINQ2DS query as follows
var result = from r in fips.AsEnumerable() select
r.Field<string>("FACILITY_PROCESS_SUB_GROUP_CODE"),
r.Field<string>("PROCESS_SUB_GROUP_NAME"),
r.Field<string>("...
when i start getting errors after the first comma.
Is this a correct guess, and how could I work around it to return a subset of the columns from the dataset in order to apply the Distinct () method to?
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You forgot the new operator and field names:
var result = from r
in fips.AsEnumerable()
select new
{
FacProcess = r.Field<string>("FACILITY_PROCESS_SUB_GROUP_CODE"),
GroupName = r.Field<string>("PROCESS_SUB_GROUP_NAME"),
Item3 = r.Field<string>("Item3")
};
You can also explicitly declare that you are going to use the type:
var result = from r
in fips.AsEnumerable()
select new MyType("InitClassParams")
{
FacProcess = r.Field<string>("FACILITY_PROCESS_SUB_GROUP_CODE"),
GroupName = r.Field<string>("PROCESS_SUB_GROUP_NAME"),
Item3 = r.Field<string>("Item3")
};
Scott Guthrie (VP Developer Devision, Microsoft) has some good information about LINQ (he talks about LINQ to SQL, but most of them apply independently).
Then apply a separate sentence:
var result = from r
in fips.AsEnumerable()
select new
{
FacProcess = r.Field<string>("FACILITY_PROCESS_SUB_GROUP_CODE"),
GroupName = r.Field<string>("PROCESS_SUB_GROUP_NAME"),
Item3 = r.Field<string>("Item3")
}
distinct;
Then put it in the list or navigate to it. Nothing will be selected / allocated / etc until something like the following is executed:
var list = result.ToList()
foreach(var item in result) {}
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