CODEWITHSUNDEEP
c#linq
Grandizer
Grandizer

Reputation: 3025

How To Add Multiple Selects to an Existing IQueryable

I have a situation where the result set is 95% the same in 3 different situations. The 5% difference depends on a given variable and thus fills in (or not) the remaining 5% of fields.

As a simple example, here is the result object that is getting returned:

public class MyResults {
  public string PropertyA { get; set; }
  public string PropertyB { get; set; }
  public string PropertyC { get; set; }
  public string PropertyD { get; set; }
  public string PropertyE { get; set; }
}

Currently I have a method where I build the results I have the following:

public List<MyResults> GetMyResults(int someParameter) {
  IQueryable<MyResults> query;

  if (someParameter == "A") {
    query = entities.Select(x => new MyResults {
      PropertyA = x.PropertyA, // Common
      PropertyB = x.PropertyB, // Common
      PropertyC = x.PropertyC, // Different
    };
  } else if (someParameter == "B") {
    query = entities.Select(x => new MyResults {
      PropertyA = x.PropertyA, // Common
      PropertyB = x.PropertyB, // Common
      PropertyD = x.PropertyD, // Different
    };
  } else {
    query = entities.Select(x => new MyResults {
      PropertyA = x.PropertyA, // Common
      PropertyB = x.PropertyB, // Common
      PropertyE = x.PropertyE, // Different
    };
  }

  return query.ToList();
}

This is a Desired way to do this:

public List<MyResults> GetMyResults(int someParameter) {
  IQueryable<MyResults> query = entities.Select(x => new MyResults {
    PropertyA = x.PropertyA, // Common
    PropertyB = x.PropertyB, // Common
    PropertyC = x.PropertyC, // Common
  };

  if (someParameter == "A") {
    query = entities.Select(x => new MyResults {
      PropertyC = x.PropertyC // Different
    });
  } else if (someParameter == "B") {
    query = entities.Select(x => new MyResults {
      PropertyD = x.PropertyD // Different
    });
  } else {
    query = entities.Select(x => new MyResults {
      PropertyE = x.PropertyE // Different
    });
  }

  return query.ToList();
}

This way the consistent fields on ALL results are the same and I only need to add what is different.

Is this possible?

Upvotes: 2

Views: 1056

Answers (1)

Gilad Green
Gilad Green

Reputation: 37299

You can use the ternary operator as follows:

return entities.Select(x => new MyResults {
    PropertyA = x.PropertyA, // Common
    PropertyB = x.PropertyB, // Common
    PropertyC = someParameter == 1 ? x.PropertyC : null,
    PropertyD = someParameter == 2 ? x.PropertyD : null,
    PropertyE = someParameter == 3 ? x.PropertyE : null,
}).ToList();

Basically as string's default is null if someParameter does not match the case for a given propertyX the properties value will be null. If it is, it will get the desired value

Upvotes: 3

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