Packages

•  package root

  

  

  Documentation/API for the Molecule library - a meta DSL for the Datomic database.

  Manual | scalamolecule.org | Github | Forum

  Definition Classes

  root

•  package molecule

  Molecule library - a Scala meta-DSL for the Datomic database.

  Molecule library - a Scala meta-DSL for the Datomic database.

  See api package for various api imports to start using Molecule.

  Sub-packages

  api		Molecule API.
  ast		Internal Molecule ASTs.
  boilerplate		Internal interfaces for auto-generated DSL boilerplate code.
  composition		Builder methods to compose molecules.
  exceptions		Exceptions thrown by Molecule.
  expression		Attribute expressions and operations.
  facade		Molecule facades to Datomic.
  factory		Implicit macro methods `m` to instantiate molecules from custom DSL molecule constructs.
  input		Input molecules awaiting input.
  macros		Internal macros generating molecule code from custom DSL molecule constructs.
  generic		Interfaces to generic information about datoms and Datomic database.
  ops		Internal operational helpers for transforming DSL to molecule.
  schema		Schema definition DSL.
  transform		Internal transformers from DSL to Model/Query/Transaction.
  util		Internal Java database functions for Datomic.

  Definition Classes

  root

•  package generic

  Definition Classes

  molecule

•  package datom

  Generic Datom attribute interfaces of all arities.

  Generic Datom attribute interfaces of all arities.

  "Generic attributes" are special pre-defined attributes that can be combined with custom attributes in molecules to return meta data:

  // Get id of Ben entity with `e`
  Person.e.name.get.head === (benEntityId, "Ben")
  
  // When was Ben's age updated? Using `txInstant`
  Person(benEntityId).age.txInstant.get.head === (42, <April 4, 2019>) // (Date)
  
  // With a history db we can access the transaction number `t` and
  // assertion/retraction statusses with `op`
  Person(benEntityId).age.t.op.getHistory === List(
    (41, t1, true),  // age 41 asserted in transaction t1
    (41, t2, false), // age 41 retracted in transaction t2
    (42, t2, true)   // age 42 asserted in transaction t2
  )

  Available generic attributes:

  • e - Entity id (Long)
  • a - Full attribute name like ":Person/name" (String)
  • v - Value of Datoms (Any)
  • t - Transaction pointer (Long/Int)
  • tx - Transaction entity id (Long)
  • txInstant - Transaction wall clock time (java.util.Date)
  • op - Operation status: assertion (true) / retraction (false)

  Definition Classes

  generic

  See also

  Tests for more generic attribute query examples.

•  package index

  Datomic Index APIs in Molecule.

  Datomic Index APIs in Molecule.
  
  Datomic maintains four indexes that contain ordered sets of datoms. Each of these indexes is named based on the sort order used:

  • EAVT - Datoms sorted by Entity-Attribute-Value-Transaction
  • AVET - Datoms sorted by Attribute-Value-Entity-Transaction
  • AEVT - Datoms sorted by Attribute-Entity-Value-Transaction
  • VAET - "Reverse index" for reverse lookup of ref types

  Create an Index molecule by instantiating an Index object with one or more arguments in the order of the Index's elements. Datoms are returned as tuples of data depending of which generic attributes you add to the Index molecule:

  // Create EAVT Index molecule with 1 entity id argument
  EAVT(e1).e.a.v.t.get === List(
    (e1, ":Person/name", "Ben", t1),
    (e1, ":Person/age", 42, t2),
    (e1, ":Golf/score", 5.7, t2)
  )
  
  // Maybe we are only interested in the attribute/value pairs:
  EAVT(e1).a.v.get === List(
    (":Person/name", "Ben"),
    (":Person/age", 42),
    (":Golf/score", 5.7)
  )
  
  // Two arguments to narrow the search
  EAVT(e1, ":Person/age").a.v.get === List(
    (":Person/age", 42)
  )

  Definition Classes

  generic

  Note

  The Molecule Index API's don't allow returning the whole Index/the whole database. So omitting arguments constructing the Index object (like EAVT.e.a.v.t.get) will throw an exception.
  Please use Datomics API if you need to return the whole database Index:
  conn.db.datoms(datomic.Database.EAVT)

  See also

  Tests for more Index query examples.

•  package schema

  Generic Schema attribute interfaces of all arities.

  Generic Schema attribute interfaces of all arities.
  
  The generic Schema interface provides attributes to build molecules that query the Schema structure of the current database.

  // List of attribute entity ids
  val attrIds: Seq[Long] = Schema.id.get
  
  // Attribute name elements
  Schema.a.part.ns.nsFull.attr.get === List (
    (":sales_Customer/name", "sales", "Customer", "sales_Customer", "name"),
    (":sales_Customer/name", "sales", "Customer", "sales_Customer", "name"),
    // etc..
  )
  
  // Datomic type and cardinality of attributes
  Schema.a.tpe.card.get === List (
    (":sales_Customer/name", "string", "one"),
    (":accounting_Invoice/invoiceLine", "ref", "many"),
  )
  
  // Optional docs and attribute options
  // These can be retrieved as mandatory or optional values
  Schema.a
        .index
        .doc$
        .unique$
        .fulltext$
        .isComponent$
        .noHistory$
        .get === List(
    (":sales_Customer/name",
      true,            // indexed
      "Customer name", // doc
      None,            // Uniqueness not set
      Some(true),      // Fulltext search set so that we can search for names
      None,            // Not a component
      None             // History is preserved (noHistory not set)
      ),
    (":accounting_Invoice/invoiceLine",
      true,                   // indexed
      "Ref to Invoice lines", // doc
      None,                   // Uniqueness not set
      None,                   // Fulltext search not set
      Some(true),             // Invoice is a component - owns invoice lines
      None                    // History is preserved (noHistory not set)
      ),
  )
  
  // Defined enum values
  Schema.a.enum.get.groupBy(_._1).map(g => g._1 -> g._2) === Map(
    ":Person/gender" -> List("female", "male"),
    ":Interests/sports" -> List("golf", "basket", "badminton")
  )
  
  // Schema transaction times
  Schema.t.tx.txInstant.get === List(
    (t1, tx1, <Date: 2018-11-07 09:28:10>), // Initial schema transaction
    (t2, tx2, <Date: 2019-01-12 12:43:27>), // Additional schema attribute definitions...
  )

  Apply expressions to narrow the returned selection of Schema data:

  // Namespaces in the "gen" partition (partition name tacit)
  Schema.part_("location").ns.get === List("Country", "Region", etc...)
  
  // Attributes in the "Person" namespace
  Schema.ns_("Person").attr.get === List("name", "age", "hobbies", etc...)
  
  // How many enum attributes?
  Schema.enum_.a(count).get === List(2)

  Definition Classes

  generic

  Note

  Schema attributes defined in Datomic's bootstrap process that are not related to the current database are transparently filtered out from all Schema queries.

  See also

  Tests for more Schema query examples.

• GenericLog
• Log
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• Log_1
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• Log_7

molecule.generic

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