Cannot apply indexing with [] to an expression of type 'object' with AsEnumerable()

Question

I get the following exception :

Cannot apply indexing with [] to an expression of type 'object'

I don't know what's the alternative to AsEnumerable() method in my case .

resultList = conn.Query(query.ToString(),
               new
               {
                  years = new[] {year, year - 1, year - 2},
                  yearsLimit = new[]
                  {
                     year,
                     year - 1
                  },
                  PeriodTypeId = periodTypeId,
                  Period = period
               }).AsEnumerable().
            GroupBy(r => r["CompanyId"]).Select(c => new //ERROR
            {
               Company = c.Key,
               Totals = c.Select(t => new
               {
                  Total1 = c.Select(t1 => new {Year = t1["Year"], Total1 = t1["Tot1"]}).ToArray(),
                  Total2 = c.Select(t2 => new {Year = t2["Year"], Total2 = t2["Tot2"]}).ToArray(),
                  Total3 = c.Select(t3 => new {Year = t3["Year"], Total3 = t3["Tot3"]}).ToArray(),

               }).FirstOrDefault()

            }).ToList();

@AnynameDonotcare so why do u need to call `AsEnumerable` again? Also, I assume in runtime `Query` returns an `IEnumerable` of some other type? — KMoussa, Nov 23 '16 at 20:42
It is `IEnumerable` https://github.com/StackExchange/dapper-dot-net/blob/91725fb309a9e5948f760fac420dd805659f0749/Dapper/SqlMapper.cs#L615 The comments say you can cast it to `IDictionary`, so a `Cast>()` before the `GroupBy()` should work according to the documentation. — Technetium, Nov 23 '16 at 20:48
I mean `Query` where you can specify the return type. Also check this http://stackoverflow.com/questions/6147121/dapper-and-anonymous-types .. I assume you can do `.OfType>` instead of `AsEnumerable` then — KMoussa, Nov 23 '16 at 20:50
@KMoussa Thanks a lot ,it works the way you explain , Could you post an answer with more documented info to accept it as an answer to the question . — Anyname Donotcare, Nov 24 '16 at 10:44

score 1 · Accepted Answer · edited May 23 '17 at 12:13

As per Dapper's Documentation, and as @Technetium noted in the comments, the non-generic version of the Query method retuns IEnumerable<dynamic>

One way to get your code working is to replace .AsEnumerable with .OfType<IDictionary<string, object>> (according to this and that code, it appears that Query actually returns IEnumerable<DapperRow>, and DapperRow inherits from IDictionary<string, object>), otherwise you can access the properties directly on the returned dynamic (e.g. r.CompanyId vs r["CompanyId"])

Also, here is an answer to a similar question on SO, for reference.

Cannot apply indexing with [] to an expression of type 'object' with AsEnumerable()

1 Answers1