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C# Querying With LINQ Query Operators Aggregates

olu adesina
olu adesina
23,007 Points
Posted by olu adesina
olu adesina
23,007 Points

where does the g.key property come from in this example

when iterate through the List<> with the FROM and IN keywords we use a variable like b in birds to access properties of each object but there is no Key property in the bird object so where is the g.key property coming from

1 Answer

Steven Parker
Steven Parker
231,275 Points
Steven Parker
Steven Parker
231,275 Points

You're right that a "bird" object doesn't have a "Key", but this is chained onto a GroupBy; and an IGrouping object (which the GroupBy creates) does have a Key. The key was selected by the function given to the GroupBy, so in this case it's the bird's "Color" value.

The "g" parameter name was probably chosen as a reminder that it represents an IGrouping object and not a bird.

olu adesina
olu adesina
23,007 Points
olu adesina
olu adesina
23,007 Points

how does c# know to assign g.key to the color property.

Steven Parker
Steven Parker
231,275 Points
Steven Parker
Steven Parker
231,275 Points

Birds.GroupBy(b => b.Color) :point_left: the lambda function selects the color as the Key.