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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

    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 api

    Public interface to be imported to use Molecule.

    Public interface to be imported to use Molecule.

    To make the Molecule macro materializations as fast as possible we try to import as few macro implicits as possible. If your application code build molecules with at the most 10 attributes, then you can do the following import to start using Molecule:

    import molecule.api.out10._

    out means "output molecule" , and 10 the maximum arity or number of attributes of your molecules.

    If you use input molecules awaiting an input then you can add inX where X is how many inputs (1, 2 or 3) you will use, for instance:

    import molecule.api.in2_out10._

    This way we keep the implicit macro def lookups to a minimum and compilation speed as fast as possible.

    Arities can be changed anytime you like. But not to a lower arity than that of the molecules you use in scope of the import.

    Definition Classes
    molecule
  • package get

    Synchronous getter methods to retrieve data from Datomic.

    Synchronous getter methods to retrieve data from Datomic.

    The Datomic On-Prem(ises) server model provides a Peer that returns data synchronously. The Peer which lives in application memory caches data aggressively and for data fitting in memory latency can be extremely low and queries return very fast. And even when access to disk is needed, clever branching is used. Memcached is also an option.

    The Datomic Cloud model data returns data asynchronously. If Datomic creates a Java API for the Cloud model, Molecule could relatively easy adapt to this model too. In the meanwhile, Future-wrapped methods in this package can be used.

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

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

    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
    api
    See also

    equivalent asynchronous getters in the getAsync package.

  • GetArray
  • GetIterable
  • GetJson
  • GetList
  • GetRaw
t

molecule.api.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
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  10. def getIterable(implicit conn: Conn): 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

    See also

    Equivalent asynchronous getAsyncIterable method.

  11. def getIterableAsOf(date: Date)(implicit conn: Conn): 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 asof/since

    Equivalent asynchronous getAsyncIterableAsOf method.

  12. def getIterableAsOf(tx: TxReport)(implicit conn: Conn): 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 getAsync 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 asof/since

    Equivalent asynchronous getAsyncIterableAsOf method.

  13. def getIterableAsOf(t: Long)(implicit conn: Conn): 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 asof/since

    Equivalent asynchronous getAsyncIterableAsOf method.

  14. def getIterableSince(date: Date)(implicit conn: Conn): 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 asof/since

    Equivalent asynchronous getAsyncIterableSince method.

  15. def getIterableSince(tx: TxReport)(implicit conn: Conn): 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 getAsync 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 asof/since

    Equivalent asynchronous getAsyncIterableSince method.

  16. def getIterableSince(t: Long)(implicit conn: Conn): 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 asof/since

    Equivalent asynchronous getAsyncIterableSince method.

  17. def getIterableWith(txData: List[_])(implicit conn: Conn): 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 on with

    Equivalent asynchronous getAsyncIterableWith method.

  18. def getIterableWith(txMolecules: Seq[Seq[Statement]]*)(implicit conn: Conn): 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 on with

    Equivalent asynchronous getAsyncIterableWith method.

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