How i compare a IQueryable to something?

Question

Hi i want compare IQueryable to "[ ]" because is what API returns when is null

i have this

var query = from Consumer in context.Consumer
 from Patient in context.Patient
 where Consumer.id == iduser
 where Patient.PATHOLOGY_id == idpato
 where Consumer.id == Patient.CONSUMER_id_patient
 select Patient;

if ( query == "[]")
{
    return  this.RedirectToAction(nameof(this.PatientCreate));
}
else
{
    return Ok(query.ToString());
}

but i can't use operattorers on IQueryable, how i do that?

Answer 1

Your query will "return" a collection of Patient objects (technically a lazy-loaded iterator, but functionally a collection), so it will not ever "equal" the string "[]". If the response from the data source is an empty JSON list, then query will most likely represent an empty collection, so you could try:

if(!query.Any())
 // no results
else
 // do something

But note that query.Any() will execute the query, and iterating the results in the view will also run the query, so you probably want to execute the query only once - ToList() is an effective way to do that:

var query = (from Consumer in context.Consumer
 from Patient in context.Patient
 where Consumer.id == iduser
 where Patient.PATHOLOGY_id == idpato
 where Consumer.id == Patient.CONSUMER_id_patient
 select Patient).ToList();

That way, you've already collected the results, so Any() will not

Finally, query.ToString() will not do what you probably think it does - I presume that you just want to pass the collection to the view, so you probably just want

return Ok(query);

Answer 2

It seems that you need something like this:

var query = from Consumer in context.Consumer
 from Patient in context.Patient
 where Consumer.id == iduser
 where Patient.PATHOLOGY_id == idpato
 where Consumer.id == Patient.CONSUMER_id_patient
 select Patient;
var result = query.ToArray();
if ( !result.Any())
{
    return  this.RedirectToAction(nameof(this.PatientCreate));
}
else
{
    return Ok(result);
}

Answer 3

var query = from Consumer in context.Consumer
 from Patient in context.Patient
 where Consumer.id == iduser
 where Patient.PATHOLOGY_id == idpato
 where Consumer.id == Patient.CONSUMER_id_patient
 select Patient;

if ( query.Count() == 0 )
{
    return  this.RedirectToAction(nameof(this.PatientCreate));
}
else
{
    return Ok(query.ToString());
}