I am trying to do a simple EF 6.0 query, but it seems it am getting nowhere and banging my head with it.

I am querying to take a single row as an object, but this return two dimentional array like below;

[
[],
[],
[{
Id: 1,
Name: Abc
}]
]

What I would like to return is the object.

{
Id: 1,
Name: Abc
}

and here is the query

var q = _operatorAssessmentContext.OperatorAssessmentQuestions
            .Select(x => x.ConditionalQuestions.Where(c => c.Id == questionId)).ToList();

So the whole idea is to change that two dimentional list into an object.

CodePudding user response：

First off, you say you want an object, but your variable, q, will be a list. I'm gonna assume you want an object, as that is what you stated.

Couple ways you can do this:

1. You can flatten the list, and then take one.
2. You can filter away empty lists in your list, and then take the first object of the first list in your list.

Personally, I would prefer the first, and the query going in to your variable, q, would look something like this:

var q = _operatorAssessmentContext
            .OperatorAssessmentQuestions
            .SelectMany(x => x.ConditionalQuestions.Where(c => c.Id == questionId))
            .FirstOrDefault();

Note the only difference is me using .SelectMany(), which will take, as an input, a list of lists holding elements of some type, T, and return one list holding elements of the same type, T.