Documentation:Tuple

Tuple

What is it

Tuple is a fancy word for something “taped together from bits and pieces of other stuff”.

Usage

This is very useful when it comes to building result sets that are not necessarily something that exists in your model - like sums or collecting names and addresses together even if they are stored in different classes. This is similar to an Anonymous type

Tuples are what an SQL server returns when you omit the " * " and write explicit stuff in the select part. In fact, the columns in the select part are the tuple definition as far as the SQL server is concerned.

OCL operators that create tuples are:

Example:

IElement elem = ocl.Evaluate(“Class1.allinstances.class2.class3->groupby(x|x.Attribute1)”);

What do I get back? A Tuple

The tuple consists of a type with a generated name and specific properties. The properties are Attribute1 and List.

Using tuples in CodeDress or C# in general

The code below shows how to access the tuple result in code:

        var onememtuple = (memoryresult[0] as ITuple);
        var onePSCase1tuple = (resultFromSQL92Joins[0] as ITuple);
        var onePSCase2tuple = (resultFromNormalJoins[0] as ITuple);
        for (int i = 0; i < onememtuple.Properties.Count; i++)
        {
          var p = onememtuple.Properties[i];
          var pPS1 = onePSCase1tuple.Properties[i];
          var pPS2 = onePSCase2tuple.Properties[i];
          if (p.AsObject != null)
          {
            Assert.IsTrue(p.AsObject.Equals(pPS1.AsObject), p.StructuralFeature.Name + " differs (sql92joins=true)");
            Assert.IsTrue(p.AsObject.Equals(pPS2.AsObject), p.StructuralFeature.Name + " differs (sql92joins=false)");
          }
        }

Using Tuples in Mdriven Designer

Tuples in OCL constitute of Parts and results are accessed either as a Part of the result if Part is derived or computed or as an Object Type

To get Category Sales on different dates


Tuple Parts (How to access the data)	Description
Part1	Product Category accessed with name `.Category` instead of `.Part1` since it is a known Type and not derived.
Part2	The total quantity sold accessed as `.Part2` since it is derived.
Part3	Date of Sale accessed as `.DateAdded` instead of `.Part3` since it is a known Type and not derived.

To get Product Sales and their percentage of total Sales


Tuple Parts (How to access the data)	Description
Part1	Product name as lower case accessed with name `.Part1` instead of `.Name` since it is derived.
Part2	The total quantity sold accessed as `.Part2` since it is derived.
Part3	Sale Percentage of Total Sales accessed with name `.Part3` since it is derived.