Declaring an implicitly typed variable inside a conditional scope and using it outside

Question

In the simplified code below

if(city == "New York City")
{
  var MyObject = from x in MyEFTable
                     where x.CostOfLiving == "VERY HIGH"
                     select x.*;

}
else
{
  var MyObject = from x in MyEFTable
                     where x.CostOfLiving == "MODERATE"
                     select x.*;

}

  foreach (var item in MyObject)
  {
     Console.WriteLine("<item details>");
  }

The MyObject variable is not available outside the conditional block. How can I repeat outside if..sse?

Answer 1

Let me clarify your confusing question. The problem is that you have two local variables, each of which has the same "inexpressible" type - a sequence of anonymous type.

I would modify your specific code as follows:

string cost = city == "NYC" ? "HIGH" : "MODERATE";
var query = from row in table 
            where row.Cost == cost 
            select new { row.Population, row.Elevation };

However, if you still need to maintain the code structure, because for some reason you can do it like this:

static IEnumerable<T> SequenceByExample<T>(T t){ return null; }
...
var query = SequenceByExample(new { Population = 0, Elevation = 0.0 } );
if (whatever)
    query = ...
else
    query = ...

"cast by example", . . , , .

Answer 2

, if, .

, , , .

. . , - .

var myObject =Enumerable.Empty<RowType>.Select(row=>select new {columnA, columnB, columnC});
if(city == "New York City")
{
  myObject= from x in MyEFTable
                     where x.CostOfLiving == "VERY HIGH"
                     select select new {columnA, columnB, columnC};
}
else
{
  myObject = from x in MyEFTable
                     where x.CostOfLiving == "MODERATE"
                     select select new {columnA, columnB, columnC};
}

:

IQueryable<RowType> partialQuery;
if(city == "New York City")
    partialQuery=MyEFTable.Where(x=>x.x.CostOfLiving == "VERY HIGH");
else
    partialQuery=MyEFTable.Where(x=>x.x.CostOfLiving == "MODERATE");
var myObject=partialQuery.Select(x=>x.new {columnA, columnB, columnC});

:

Expression<Predicate<RowType>> filter;//Note that this is an Expression, not just a delegate
if(city == "New York City")
  filter=x=>x.x.CostOfLiving == "VERY HIGH";
else
  filter=x=>x.x.CostOfLiving == "MODERATE";
var myObject=MyEFTable.Where(filter).Select(x=>x.new {columnA, columnB, columnC});

:

string s;
if(city == "New York City")
  s="VERY HIGH";
else
  s="MODERATE";
var myObject=MyEFTable.Where(x=>x.CostOfLiving == s).Select(x=>x.new {columnA, columnB, columnC});

, , .

Answer 3

:

var ret = default(object);

Answer 4

:

System.Linq.IQueryable<MyEFTable Object type> MyObject = null;
if(city == "New York City")
{
  MyObject = from x in MyEFTable
             where x.CostOfLiving == "VERY HIGH"
             select x.*;
}
else
{
  MyObject = from x in MyEFTable
             where x.CostOfLiving == "MODERATE"
             select x.*;
}

foreach (var item in MyObject)
{
  Console.WriteLine("<item details>");
}

Answer 5

List<MyObject> list = null; 

if(city == "New York City")    
   list = (from x in MyEFTable  where x.CostOfLiving == "VERY HIGH"
                     select x.*).ToList();       
else    
   list = (from x in MyEFTable where x.CostOfLiving == "MODERATE"
                     select x.*).ToList();        

foreach (var item in list)   
     Console.WriteLine("<item details>");    

Answer 6

if, foreach.

, if, , .

foreach, IEnumerable.

Answer 7

MyObject var :

var MyObject = from x in MyEFTable
                     where x.CostOfLiving == "SOMETHING THAT'LL RETURN NO ROWS"
                     select x.*;

MyObject.

:

if(city == "New York City")
{
  MyObject = from x in MyEFTable
                     where x.CostOfLiving == "VERY HIGH"
                     select x.*;

}
else
{
  MyObject = from x in MyEFTable
                     where x.CostOfLiving == "MODERATE"
                     select x.*;

}