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  • 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

    action Actions on molecules and entities.
    api Molecule import interfaces of various arities.
    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.
    generic Interfaces to generic information about datoms and Datomic database.
    input Input molecules awaiting input.
    macro Internal macros generating molecule code from custom DSL molecule constructs.
    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 action

    Various actions and operations on molecules and entities.

    Various actions and operations on molecules and entities.

    Definition Classes
    molecule
  • package get

    Package with various synchronous getter methods to retrieve data from Datomic with molecules.

    Package with various synchronous getter methods to retrieve data from Datomic with molecules.

    For the Datomic Peer model, Datomic returns data synchronously. The Peer lives in application memory and caches data aggressively to save roundtrips to disk or memcached. Query results that can fit in memory will therefore have near-zero latency and return extremely fast.

    Molecule has not yet addressed the Client api although the query engine would be the same as for the current Peer version.

    Molecule has 5 groups of getters each returning data in various formats:

    • GetList - default getter returning Lists of tuples. Convenient typed data, suitable for smaller data sets
    • GetArray - fastest retrieved typed data set. Can be traversed with a fast while loop
    • GetIterable - for lazily traversing row by row
    • GetRaw - fastest retrieved raw un-typed data from Datomic
    • GetJson - data formatted as Json string

    Getters in each of the 5 groups come with 5 time-dependent variations:

    • get [current data]
    • getAsOf
    • getSince
    • getWith
    • getHistory

    Each time variation has various overloads taking different parameters (see each group for more info).

    Definition Classes
    action
  • GetArray
  • GetIterable
  • GetJson
  • GetList
  • GetRaw
t

molecule.action.get

GetIterable

trait GetIterable[Tpl] extends AnyRef

Data getter methods on molecules that return Iterable[Tpl].

Suitable for data sets that are lazily consumed.

Self Type
Molecule[Tpl]
Source
GetIterable.scala
Linear Supertypes
AnyRef, Any
Known Subclasses
Molecule, Molecule01, Molecule02, Molecule03, Molecule04, Molecule05, Molecule06, Molecule07, Molecule08, Molecule09, Molecule10, Molecule11, Molecule12, Molecule13, Molecule14, Molecule15, Molecule16, Molecule17, Molecule18, Molecule19, Molecule20, Molecule21, Molecule22
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  10. def getIterable(implicit conn: Conn, ev: ClassTag[Tpl]): Iterable[Tpl]

    Get Iterable of all rows as tuples matching the molecule.

    Get Iterable of all rows as tuples matching the molecule.

    Rows are lazily type-casted on each call to iterator.next().

    Person.name.age.getIterable.toList === List(
  ("Ben", 42),
  ("Liz", 37),
)
    conn

    Implicit Conn value in scope

    returns

    Iterable[Tpl] where Tpl is a tuple of types matching the attributes of the molecule

  11. def getIterableAsOf(date: Date)(implicit conn: Conn, ev: ClassTag[Tpl]): Iterable[Tpl]

    Get Iterable of all rows as tuples matching molecule as of date.

    Get Iterable of all rows as tuples matching molecule as of date.

    Get data at a human point in time (a java.util.Date).

    val beforeInsert = new java.util.Date

// Insert
val tx1 = Person.name.age insert List(
  ("Ben", 42),
  ("Liz", 37)
)
val List(ben, liz) = tx1.eids
val afterInsert = new java.util.Date

// Update
val tx2 = Person(ben).age(43).update
val afterUpdate = new java.util.Date

// Retract
val tx3 = ben.retract
val afterRetract = new java.util.Date

// Get Iterable of all rows as of beforeInsert
val iterable0: Iterable[(String, Int)] = Person.name.age.getIterableAsOf(beforeInsert)
val iterator0: Iterator[(String, Int)] = iterable0.iterator
iterator0.hasNext === false // Nothing yet

// Get Iterable of all rows as of afterInsert
val iterable1: Iterable[(String, Int)] = Person.name.age.getIterableAsOf(afterInsert)
val iterator1: Iterator[(String, Int)] = iterable1.iterator

// Type casting lazily performed with each call to `next`
iterator1.next === ("Ben", 42)
iterator1.next === ("Liz", 37)

// Get Iterable of all rows as of afterUpdate
val iterable2: Iterable[(String, Int)] = Person.name.age.getIterableAsOf(afterUpdate)
val iterator2: Iterator[(String, Int)] = iterable2.iterator

// Type casting lazily performed with each call to `next`
iterator2.next === ("Ben", 43) // Ben now 43
iterator2.next === ("Liz", 37)

// Get Iterable of all rows as of afterRetract
val iterable3: Iterable[(String, Int)] = Person.name.age.getIterableAsOf(afterRetract)
val iterator3: Iterator[(String, Int)] = iterable3.iterator

// Type casting lazily performed with each call to `next`
iterator3.next === ("Liz", 37)
iterator3.hasNext === false // Ben gone
    date

    java.util.Date

    conn

    Implicit Conn value in scope

    returns

    Iterable[Tpl] where Tpl is tuple of data matching molecule

    See also

    Manual on getAsOf

  12. def getIterableAsOf(tx: TxReport)(implicit conn: Conn, ev: ClassTag[Tpl]): Iterable[Tpl]

    Get Iterable of all rows as tuples matching molecule as of tx.

    Get Iterable of all rows as tuples matching molecule as of tx.

    Datomic's internal asOf method can take a transaction entity id as argument to retrieve a database value as of that transaction (including).

    Instead of supplying the transaction entity id, in Molecule we supply a TxReport that contains the transaction entity id (which is used as argument to Datomic internally). This is more convenient when using Molecule since we get a TxReport from transaction operations like get, update, retract etc.

    // Insert (tx report 1)
val tx1 = Person.name.age insert List(
  ("Ben", 42),
  ("Liz", 37)
)
val List(ben, liz) = tx1.eids

// Update (tx report 2)
val tx2 = Person(ben).age(43).update

// Retract (tx report 3)
val tx3 = ben.retract

// Get Iterable of all rows as of tx1 (after insert)
val iterable1: Iterable[(String, Int)] = Person.name.age.getIterableAsOf(tx1)
val iterator1: Iterator[(String, Int)] = iterable1.iterator

// Type casting lazily performed with each call to `next`
iterator1.next === ("Ben", 42)
iterator1.next === ("Liz", 37)

// Get Iterable of all rows as of tx2 (after update)
val iterable2: Iterable[(String, Int)] = Person.name.age.getIterableAsOf(tx2)
val iterator2: Iterator[(String, Int)] = iterable2.iterator

// Type casting lazily performed with each call to `next`
iterator2.next === ("Ben", 43) // Ben now 43
iterator2.next === ("Liz", 37)

// Get Iterable of all rows as of tx3 (after retract)
val iterable3: Iterable[(String, Int)] = Person.name.age.getIterableAsOf(tx3)
val iterator3: Iterator[(String, Int)] = iterable3.iterator

// Type casting lazily performed with each call to `next`
iterator3.next === ("Liz", 37)
iterator3.hasNext === false // Ben gone
    tx

    TxReport (returned from all molecule transaction operations)

    conn

    Implicit Conn value in scope

    returns

    Iterable[Tpl] where Tpl is tuple of data matching molecule

    See also

    Manual on getAsOf

  13. def getIterableAsOf(t: Long)(implicit conn: Conn, ev: ClassTag[Tpl]): Iterable[Tpl]

    Get Iterable of all rows as tuples matching molecule as of transaction time t.

    Get Iterable of all rows as tuples matching molecule as of transaction time t.

    Transaction time t is an auto-incremented transaction number assigned internally by Datomic.

    Call getIterableAsOf for large result sets to maximize runtime performance. Data is lazily type-casted on each call to next on the iterator.

    t can for instance be retrieved in a getHistory call for an attribute and then be used to get data as of that point in time (including that transaction):

    // Insert (t 1028)
val List(ben, liz) = Person.name.age insert List(
  ("Ben", 42),
  ("Liz", 37)
) eids

// Update (t 1031)
Person(ben).age(43).update

// Retract (t 1032)
ben.retract

// History of Ben
Person(ben).age.t.op.getHistory.sortBy(r => (r._2, r._3)) === List(
  (42, 1028, true),  // Insert:  42 asserted
  (42, 1031, false), // Update:  42 retracted
  (43, 1031, true),  //          43 asserted
  (43, 1032, false)  // Retract: 43 retracted
)

// Get Iterable of all rows as of transaction t 1028 (after insert)
val iterable1: Iterable[(String, Int)] = Person.name.age.getIterableAsOf(1028)
val iterator1: Iterator[(String, Int)] = iterable1.iterator

// Type casting lazily performed with each call to `next`
iterator1.next === ("Liz", 37)
iterator1.next === ("Ben", 42)

// Get Iterable of all rows as of transaction t 1031 (after update)
val iterable2: Iterable[(String, Int)] = Person.name.age.getIterableAsOf(1031)
val iterator2: Iterator[(String, Int)] = iterable2.iterator

// Type casting lazily performed with each call to `next`
iterator2.next === ("Liz", 37)
iterator2.next === ("Ben", 43) // Ben now 43

// Get Iterable of all rows as of transaction t 1032 (after retract)
val iterable3: Iterable[(String, Int)] = Person.name.age.getIterableAsOf(1032)
val iterator3: Iterator[(String, Int)] = iterable3.iterator

// Type casting lazily performed with each call to `next`
iterator3.next === ("Liz", 37)
iterator3.hasNext === false // Ben gone
    t

    Transaction time t

    conn

    Implicit Conn value in scope

    returns

    Iterable[Tpl] where Tpl is tuple of data matching molecule

    See also

    Manual on getAsOf

  14. def getIterableSince(date: Date)(implicit conn: Conn, ev: ClassTag[Tpl]): Iterable[Tpl]

    Get Iterable of all rows as tuples matching molecule since date.

    Get Iterable of all rows as tuples matching molecule since date.

    Get data added/retracted since a human point in time (a java.util.Date).

    // Transact 3 times (`inst` retrieves transaction time from tx report)
val date1 = Person.name("Ann").save.inst
val date2 = Person.name("Ben").save.inst
val date3 = Person.name("Cay").save.inst

// Current values
Person.name.getIterable.iterator.toList === List("Ann", "Ben", "Cay")

// Ben and Cay added since date1
Person.name.getIterableSince(date1).iterator.toList === List("Ben", "Cay")

// Cay added since date2
Person.name.getIterableSince(date2).iterator.toList === List("Cay")

// Nothing added since date3
Person.name.getIterableSince(date3).iterator.toList === Nil
    date

    java.util.Date

    conn

    Implicit Conn value in scope

    returns

    Iterable[Tpl] where Tpl is tuple of data matching molecule

    See also

    Manual on since

  15. def getIterableSince(tx: TxReport)(implicit conn: Conn, ev: ClassTag[Tpl]): Iterable[Tpl]

    Get Iterable of all rows as tuples matching molecule since tx.

    Get Iterable of all rows as tuples matching molecule since tx.

    Datomic's internal since method can take a transaction entity id as argument to retrieve a database value since that transaction (excluding the transaction itself).

    Instead of supplying the transaction entity id, in Molecule we supply a TxReport that contains the transaction entity id (which is used as argument to Datomic internally). This is more convenient when using Molecule since we get a TxReport from transaction operations like get, update, retract etc.

    // Get tx reports for 3 transactions
val tx1 = Person.name("Ann").save
val tx2 = Person.name("Ben").save
val tx3 = Person.name("Cay").save

// Current values
Person.name.getIterable.iterator.toList === List("Ann", "Ben", "Cay")

// Ben and Cay added since tx1
Person.name.getIterableSince(tx1).iterator.toList === List("Ben", "Cay")

// Cay added since tx2
Person.name.getIterableSince(tx2).iterator.toList === List("Cay")

// Nothing added since tx3
Person.name.getIterableSince(tx3).iterator.toList === Nil
    tx

    TxReport

    conn

    Implicit Conn value in scope

    returns

    Iterable[Tpl] where Tpl is tuple of data matching molecule

    See also

    Manual on since

  16. def getIterableSince(t: Long)(implicit conn: Conn, ev: ClassTag[Tpl]): Iterable[Tpl]

    Get Iterable of all rows as tuples matching molecule since transaction time t.

    Get Iterable of all rows as tuples matching molecule since transaction time t.

    Transaction time t is an auto-incremented transaction number assigned internally by Datomic.

    Call getIterableSince for large result sets to maximize runtime performance. Data is lazily type-casted on each call to next on the iterator.

    t can for instance be retrieved calling t on the tx report returned from transactional operations and then be used to get data since that point in time (excluding that transaction):

    // 3 transaction times `t`
val t1 = Person.name("Ann").save.t
val t2 = Person.name("Ben").save.t
val t3 = Person.name("Cay").save.t

// Current values as Iterable
Person.name.getIterable.iterator.toList === List("Ann", "Ben", "Cay")

// Ben and Cay added since transaction time t1
Person.name.getIterableSince(t1).iterator.toList === List("Ben", "Cay")

// Cay added since transaction time t2
Person.name.getIterableSince(t2).iterator.toList === List("Cay")

// Nothing added since transaction time t3
Person.name.getIterableSince(t3).iterator.toList === Nil
    t

    Transaction time t

    conn

    Implicit Conn value in scope

    returns

    Iterable[Tpl] where Tpl is tuple of data matching molecule

    See also

    Manual on since

  17. def getIterableWith(txData: List[_])(implicit conn: Conn, ev: ClassTag[Tpl]): Iterable[Tpl]

    Get Iterable of all rows as tuples matching molecule with applied raw transaction data.

    Get Iterable of all rows as tuples matching molecule with applied raw transaction data.

    Apply raw transaction data to in-memory "branch" of db without affecting db to see how it would then look:

    // Live size of Person db
Person.name.get.size === 150

// Read some transaction data from file
val data_rdr2 = new FileReader("examples/resources/seattle/seattle-data1a.dtm")
val newDataTx = Util.readAll(data_rdr2).get(0).asInstanceOf[java.util.List[Object]]

// Imagine future db - 100 persons would be added, apparently
Person.name.getIterableWith(newDataTx).size === 250
    txData

    Raw transaction data as java.util.List[Object]

    conn

    Implicit Conn value in scope

    returns

    Iterable of molecule data

    See also

    Manual

  18. def getIterableWith(txMolecules: Seq[Seq[Statement]]*)(implicit conn: Conn, ev: ClassTag[Tpl]): Iterable[Tpl]

    Get Iterable of all rows as tuples matching molecule with applied molecule transaction data.

    Get Iterable of all rows as tuples matching molecule with applied molecule transaction data.

    Apply one or more molecule transactions to in-memory "branch" of db without affecting db to see how it would then look:

    // Current state
val ben = Person.name("Ben").likes("pasta").save.eid

// Base data
Person.name.likes.getIterableWith(
  // apply imaginary transaction data
  Person(ben).likes("sushi").getUpdateTx
).iterator.toList === List(
  // Effect: Ben would like sushi if tx was applied
  ("Ben", "sushi")
)

// Current state is still the same
Person.name.likes.get === List(
  ("Ben", "pasta")
)

    Multiple transactions can be applied to test more complex what-if scenarios!

    txMolecules

    Transaction statements from applied Molecules with test data

    conn

    Implicit Conn value in scope

    returns

    Iterable of molecule data

    See also

    Manual

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