DocumentDB LINQ Query - Select method not supported - join

Question

The Application:
.Net Standard Class Library (Containing a series of Repositories)
Latest version https://www.nuget.org/packages/Microsoft.Azure.DocumentDB.Core
Azure Cosmos DB Emulator
Sample Document Structure:
{
"ProfileName": "User Profile 123",
"Country": "UK",
"Tags": [{
"Id": "686e4c9c-f1ab-40ce-8472-cc5d63597263",
"Name": "Tag 1"
},
{
"Id": "caa2c2a0-cc5b-42e3-9943-dcda776bdc20",
"Name": "Tag 2"
}],
"Topics": [{
"Id": "baa2c2a0-cc5b-42e3-9943-dcda776bdc20",
"Name": "Topic A"
},
{
"Id": "aaa2c2a0-cc5b-42e3-9943-dcda776bdc30",
"Name": "Topic B"
},
{
"Id": "eaa2c2a0-cc5b-42e3-9943-dcda776bdc40",
"Name": "Topic C"
}]
}
The Problem:
The issue I have is that any LINQ query I execute that contains a .Select, returns an error stating that the Select method is not supported.
What I Need?
I want to be able to use a LINQ Expression to return all documents WHERE:
Country = UK
Tags contains a specific GUID
Topics contain a specific GUID

Answer 1

What I Need? I want to be able to use a LINQ Expression to return all documents
In your case, the Tags and Topic are object array, if you use the following linq code it will get null.
var q = from d in client.CreateDocumentQuery<Profile>(
UriFactory.CreateDocumentCollectionUri("database", "coll"))
where d.Country == "UK" && d.Tags.Contains(new Tag
{
Id = "686e4c9c-f1ab-40ce-8472-cc5d63597264"
}) && d.Topics.Contains(new Topic
{
Id = "baa2c2a0-cc5b-42e3-9943-dcda776bdc22"
})
select d;
I also try to override IEqualityComparer for Tag and Topic
public class CompareTag: IEqualityComparer<Tag>
{
public bool Equals(Tag x, Tag y)
{
return x != null && x.Id.Equals(y?.Id);
}
public int GetHashCode(Tag obj)
{
throw new NotImplementedException();
}
}
And try it again then get Contains is not supported by Azure documentDb SDK
var q = from d in client.CreateDocumentQuery<Profile>(
UriFactory.CreateDocumentCollectionUri("database", "coll"))
where d.Country == "UK" && d.Tags.Contains(new Tag
{
Id = "686e4c9c-f1ab-40ce-8472-cc5d63597264"
},new CompareTag()) && d.Topics.Contains(new Topic
{
Id = "baa2c2a0-cc5b-42e3-9943-dcda776bdc22"
}, new CompareTopic())
select d;
My workaround is that we could use the SQL query directly. It works correctly on my side. We also could test it on the Azure portal.
SELECT * FROM root WHERE (ARRAY_CONTAINS(root.Tags, {"Id": "686e4c9c-f1ab-40ce-8472-cc5d63597263"}, true) And ARRAY_CONTAINS(root.Topics, {"Id": "baa2c2a0-cc5b-42e3-9943-dcda776bdc20"}, true) And root.Country = 'UK' )
Query with SDK
FeedOptions queryOptions = new FeedOptions { MaxItemCount = -1 };
var endpointUrl = "https://cosmosaccountName.documents.azure.com:443/";
var primaryKey = "VNMIT4ydeC.....";
var client = new DocumentClient(new Uri(endpointUrl), primaryKey);
var sql = "SELECT * FROM root WHERE (ARRAY_CONTAINS(root.Tags, {\"Id\":\"686e4c9c-f1ab-40ce-8472-cc5d63597263\"},true) AND ARRAY_CONTAINS(root.Topics, {\"Id\":\"baa2c2a0-cc5b-42e3-9943-dcda776bdc20\"},true) AND root.Country = \"UK\")";
var profileQuery = client.CreateDocumentQuery<Profile>(
UriFactory.CreateDocumentCollectionUri("dbname", "collectionName"),sql, queryOptions).AsDocumentQuery();
var profileList = new List<Profile>();
while (profileQuery.HasMoreResults)
{
profileList.AddRange(profileQuery.ExecuteNextAsync<Profile>().Result);
}
Profile.cs file
public class Profile
{
[JsonProperty(PropertyName = "id")]
public string Id { get; set; }
public string Country { get; set; }
public string ProfileName { get; set; }
public Tag[] Tags{ get; set; }
public Topic[] Topics { get; set; }
}
Topic.cs
public class Topic
{
public string Id { get; set; }
public string Name { get; set; }
}
Tag.cs
public class Tag
{
public string Id { get; set; }
public string Name { get; set; }
}