public void JoinLists()
{
var programmingLanguages = ProgrammingLanguageRepository.GetProgrammingLanguages().ToList();
var programmingLanguageTypes = ProgrammingLanguageTypeRepository.GetProgrammingLanguageTypes().ToList();
/* Join */
// Allows to combine the desired data into one query and tranform the results into a new Type
// The caller(programmingLanguages) is considered the outer list
// The parameter(programmingLanguageTypes) is considered the inner list
/*
* Parameters:
* - outerKeySelector: Key selector that is used to match the columns on the join from the outer list
* - innerKeySelector: Key selector that is used to match the columns on the join from the inner list
* - resultSelector: Select delegate used for projection
*/
var programmingLanguagesAndTypes = programmingLanguages.Join(programmingLanguageTypes, pl => pl.TypeId, plt => plt.TypeId, (pl, plt) => new
{
pl.Name, plt.Type
}).ToList();
Assert.AreEqual(programmingLanguagesAndTypes.First().Name, "C#");
Assert.AreEqual(programmingLanguagesAndTypes.First().Type, "Object Oriented");
Assert.AreEqual(programmingLanguagesAndTypes.Last().Name, "Ruby");
Assert.AreEqual(programmingLanguagesAndTypes.First().Type, "Object Oriented");
}
public void GroupingByParentData()
{
// GroupBy (Parent Property)
var programmingLanguages = ProgrammingLanguageRepository.GetProgrammingLanguages().ToList();
var programmingLanguageTypes = ProgrammingLanguageTypeRepository.GetProgrammingLanguageTypes().ToList();
var programmingLanguagesTypeQuery = programmingLanguages.Join(programmingLanguageTypes, pg => pg.TypeId,
pgt => pgt.TypeId, (pl, plt) => new
{
// We save an instance of the programming language to access the properties on the future
ProgrammingLanguageInstance = pl,
ProgrammingLanguageType = plt
});
// Getting the Market share of programming languages, Ordering by programming language Type name
var programmingLanguagesMarketShare = programmingLanguagesTypeQuery.GroupBy(
pg => pg.ProgrammingLanguageType, pg => pg.ProgrammingLanguageInstance.MarketShare, (groupKey, marketShareTotal) => new
{
Key = groupKey.Type,
MarketShare = marketShareTotal.Sum()
}).ToList();
// Three results (total):
Assert.AreEqual(programmingLanguagesMarketShare.First().Key, "Object Oriented");
Assert.AreEqual(programmingLanguagesMarketShare.First().MarketShare, 77);
Assert.AreEqual(programmingLanguagesMarketShare[1].Key, "Imperative");
Assert.AreEqual(programmingLanguagesMarketShare[1].MarketShare, 4);
Assert.AreEqual(programmingLanguagesMarketShare.Last().Key, "Functional");
Assert.AreEqual(programmingLanguagesMarketShare.Last().MarketShare, 19);
}