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

Explanation 1

Using tuples in mdriven designer

Tuples in OCL constitute of Parts and the 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:

2024-06-30 08h08 48.png
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.

Explanation 2

To get Product Sales and their percentage of total Sales:

2024-06-30 08h26 24.png
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.

See alsoPSEvalTuples, SQLPassthrough

This page was edited 13 days ago on 07/02/2024. What links here