Load only what a projection reads from a collection

[SimonCropp]

A projection that reads a collection through LINQ reads the item's properties off the lambda's own parameter:

GroupIds = _.AccessGroups.Select(_ => _.AccessGroupId).ToList()

ProjectionAnalyzer only followed member chains from the projection's parameter, so it recorded AccessGroups and nothing under it. A navigation with nothing recorded under it is loaded whole: every column of every item, with whatever the request selected under it loaded through an Include instead of a nested select.

The scalars the lambdas of the chain read from an item are now recorded under the collection, here AccessGroups.AccessGroupId, so only they are loaded.

Still loaded whole

When the lambdas need more than scalars of an item:

• The items themselves come out, as from a Where with no Select after it, or FirstOrDefault.
• A lambda reads a navigation of an item, or passes an item to a method.
• There is no lambda, as in _.Items.Count().

Impact

No API change. A query for a field or filter with such a projection selects fewer columns, and returns the same data. In the app this came from, two snapshots changed, in SQL only.

Changes

• ProjectionAnalyzer records the item properties.
• Nine tests in ProjectionAnalyzerTests.
• Version 36.1.0.