RavenDB: Deserializing nested arrays - ravendb

Question

Suppose I have the following class to be serialized and stored as a RavenDB's document:
public class Block
{
public string Id { get; set; }
public List<List<dynamic>> data { get; set; }
}
After storing, a document like this can be seen in the database:
{
"Id": "f539770a",
"columns": [
[ 90, 91, 92, 93, 94 ],
[ "C", "D", "A", "B", "C" ]
] }
I want to execute a query to retrieve the Nth list of values inside the "Columns" field:
session.Query<Block>().Where(b => b.Id == "f539770a").Select(b =>b.columns[i]);
And I get the following Error:
{"Cannot deserialize the current JSON object (e.g. {\"name\":\"value\"}) into type 'System.Collections.Generic.List`1[System.Object]' because the type requires a JSON array (e.g. [1,2,3]) to deserialize correctly.\r\nTo fix this error either change the JSON to a JSON array (e.g. [1,2,3]) or change the deserialized type so that it is a normal .NET type (e.g. not a primitive type like integer, not a collection type like an array or List) that can be deserialized from a JSON object. JsonObjectAttribute can also be added to the type to force it to deserialize from a JSON object.\r\nPath '__document_id'."}
It seems like the query is working (the server returns http 200), but there is a client-side deserialization problem.
Am I missing something?
Thanks!!
UPDATE:
I changed the data structure as the error seems to suggest:
public class Column
{
public List<dynamic> data { get; set; }
}
public class Block
{
public string Id { get; set; }
public List<Column> columns { get; set; }
}
The stored document is like:
{
"Id": "f539770a",
"columns": [
{ "data": [ 95, 96, 97, 98, 99 ] },
{ "data": [ "D", "A", "B", "C", "D" ] }
]}
After executing this query:
session.Query<Block>().Include<Block>(b => b.columns).Where(b => b.parentFileId == dbFileDescriptor.Id).Select(b => b.columns[i])
I get no exception, but the nested array is not loaded:

Answer 1

Remove the Include. That's not what it's used for. The Include is for pre-loading references to other documents so you don't have to make multiple database trips. You might be making RavenDB look for Block's and their corresponding Column documents. See documentation here.
session.Query<Block>().Where(b => b.parentFileId == dbFileDescriptor.Id).Select(b => b.data[i]);
EDIT:
If you're going to look something by the Id, use Load not Query.
session.Load<Block>("f539770a").data[i];
I verified that this works with a raven unit test using RavenDB.Tests.Helpers nuget package and Shouldly for the assertion.
public class SoQuestion : RavenTestBase
{
[Fact]
public void GetBlock_Success()
{
using (var docStore = NewDocumentStore())
{
using (var session = docStore.OpenSession())
{
session.Store(new Block
{
Id = "f539770a",
data = new List<List<dynamic>>()
{
new List<dynamic>()
{
90,
91,
92,
93,
94
},
new List<dynamic>()
{
"C",
"D",
"A",
"B",
"C"
}
}
});
session.SaveChanges();
}
docStore.WaitForStaleIndexesToComplete();
//Act
var block = GetBlock(docStore);
//Assert
block.ShouldNotBe(null);
block.data.ShouldNotBeEmpty();
}
}
private Block GetBlock(IDocumentStore documentStore)
{
using (var session = documentStore.OpenSession())
{
return session.Load<Block>("f539770a");
}
}
public class Block
{
public string Id { get; set; }
public List<List<dynamic>> data { get; set; }
}
}