Feature Idea: Query generator

[riannucci]

We could add a tool to generate a per-model typed Query object. So instead of:

q := datastore.NewQuery("Kind").Eq("Property", 1).Lt("OtherThing", "value")

You would have:

/// PropertyEq has type func(...int) *KindQuery
// OtherLt has type func(...string) *KindQuery
q := KindQuery().PropertyEq(1).OtherThingLt("value")

This would avoid pitfalls around runtime type mismatches and typos.

And then you win the world :)

[riannucci]

A possible alternate syntax could look like

// Property() has type *KindQueryProperty
// OtherThing() has type *KindQueryOtherThing
// Both would have Eq, Lt, Gt, Gte, Lte, etc. of the type appropriate for that property

q := KindQuery().Property().Eq(1).OtherThing().Lt("value")