ast
The collection is treated as immutable internally but an ArrayBuffer is more effecient then Collection.list at appending which is mostly what the collection does
For Dynamic Infix Splices
Entities represent the actual tables/views being selected.
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An Opinion represents a piece of data that needs to be propagated through AST transformations but is not directly related to how ASTs are transformed in most stages.
An Opinion represents a piece of data that needs to be propagated through AST transformations but is not directly
related to how ASTs are transformed in most stages. For instance, Renameable controls how columns are named (i.e. whether to use a
NamingStrategy or not) after most of the SQL transformations are done. Some transformations (e.g. RenameProperties
will use Opinions or even modify them so that the correct kind of query comes out at the end of the normalizations.
That said, Opinions should be transparent in most steps of the normalization.
Properties generally represent column selection from a table or invocation of some kind of method from some other object.
Properties generally represent column selection from a table or invocation of some kind of method from some other object. Typically, something like
`SELECT p.name FROM People p`comes from something like
`Map(Entity("People"), Ident("p"), Property(Ident(p), "name"))`
Properties also have
an Opinion about how the NamingStrategy affects their name. For example something like
Property.Opinionated(Ident(p), "s_name", Fixed) will become p.s_name even if the NamingStrategy is UpperCase
(whereas Property(Ident(p), "s_name") would become p.S_NAME). When Property is constructed without Opinionated
being used, the default opinion ByStrategy is used.SELECT p.name FROM People p
something like
`Map(Entity("People"), Ident("p"), Property(Ident(p), "name"))`
Properties also have
an Opinion about how the `NamingStrategy` affects their name. For example something like
`Property.Opinionated(Ident(p), "s_name", Fixed)` will become `p.s_name` even if the `NamingStrategy` is `UpperCase`
(whereas `Property(Ident(p), "s_name")` would become `p.S_NAME`). When Property is constructed without `Opinionated`
being used, the default opinion `ByStrategy` is used.
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Ident represents a single variable name, this typically refers to a table but not always.
Ident represents a single variable name, this typically refers to a table but not always. Invisible identities are a rare case where a user returns an embedded table from a map clause:
case class Emb(id: Int, name: String) extends Embedded
case class Parent(id: Int, name: String, emb: Emb) extends Embedded
case class GrandParent(id: Int, par: Parent)
query[GrandParent]
.map(g => g.par).distinct
.map(p => (p.name, p.emb)).distinct
.map(tup => (tup._1, tup._2)).distinct
}
In these situations, the identity whose properties need to be expanded in the ExpandNestedQueries phase, needs to be marked invisible.
Entities represent the actual tables/views being selected. Typically, something like:
comes from something like:`Map(Entity("People", Nil), Ident("p"), Property(Ident(p), "name"))`.When you define aquerySchema, the fields you mention inside becomePropertyAliass. For example something like:`querySchema[Person]("t_person", _.name -> "s_name")`Becomes something like:`Entity("t_person", List(PropertyAlias(List("name"), "s_name"))) { def renameable = Fixed }`Note that Entity has an Opinion calledrenameablewhich will be the valueFixedwhen aquerySchemais specified. That means that even if theNamingSchemaisUpperCase, the resulting query will selectt_personas opposed toT_PERSONorPerson.SELECT p.name FROM People psomething like:`Map(Entity("People", Nil), Ident("p"), Property(Ident(p), "name"))`.When you define a `querySchema`, the fields you mention inside become `PropertyAlias`s. For example something like:`querySchema[Person]("t_person", _.name -> "s_name")`Becomes something like:`Entity("t_person", List(PropertyAlias(List("name"), "s_name"))) { def renameable = Fixed }`Note that Entity has an Opinion called `renameable` which will be the value `Fixed` when a `querySchema` is specified. That means that even if the `NamingSchema` is `UpperCase`, the resulting query will select `t_person` as opposed to `T_PERSON` or `Person`.