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<message> | <message>Explain how to use Tuples. </message> | ||
Tuples are what an SQL server returns when you omit the | ==== 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 [https://learn.microsoft.com/en-us/dotnet/csharp/fundamentals/types/anonymous-types 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: | OCL operators that create tuples are: | ||
| Line 8: | Line 13: | ||
* [[OCLOperators collect|Collect]] | * [[OCLOperators collect|Collect]] | ||
==== Example: ==== | ===== Example: ===== | ||
IElement elem = ocl.Evaluate(“Class1.allinstances.class2.class3->groupby(x|x.Attribute1)”); | |||
What do I get back? A Tuple | 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. | 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: | The code below shows how to access the tuple result in code: | ||
<pre> | <pre> | ||
Revision as of 13:29, 25 June 2024
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)");
}
}
See also PSEvalTuples, SQLPassthrough