Molecule0.22.6 < Back

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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

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
Definition Classes
molecule
package exception
Definition Classes
api
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.
package getAsync
Asynchronous getter methods to retrieve data from Datomic.
Asynchronous getter methods to retrieve data from Datomic.
For convenience, all synchronous getter methods from the get package are here wrapped in Futures.
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 asynchronous getters, each returning Futures of data in various formats:
- GetAsyncArray - fastest retrieved typed data set. Can be traversed with a fast while loop
- GetAsyncIterable - for lazily traversing row by row
- GetAsyncJson - data formatted as Json string
- GetAsyncList - default getter returning Lists of tuples. Convenient typed data, suitable for smaller data sets
- GetAsyncRaw - fastest retrieved raw un-typed data from Datomic
Getters in each of the 5 groups come with 5 time-dependent variations:
- getAsync [current data]
- getAsyncAsOf
- getAsyncSince
- getAsyncWith
- getAsyncHistory
Each time variation has various overloads taking different parameters (see each group for more info).
Definition Classes
api
See also
equivalent synchronous getters in the get package.
Entity
EntityOps
Molecule
OptionalMapOps
ShowDebug
TxMethods
core
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molecule.api

EntityOps

trait EntityOps extends AnyRef

Operations on multiple entities.

Source: EntityOps.scala

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def debugRetract(eids: Iterable[Long], txMetaDataMolecules: MoleculeBase*)(implicit conn: Conn): Unit

Debug retracting multiple entities with optional transaction meta data.

Debug retracting multiple entities with optional transaction meta data.

Without affecting the database, a multiple entity retract action can be debugged by adding a 'D' (for 'Debug') to the retract method.

Here we debug a possible retraction of two comment entities with transaction meta data asserting that the retraction was done by Ben Goodman:

debugRetract(Seq(commentEid1, commentEid2), MetaData.user("Ben Goodman"))

This will print debugging info about the retraction to output (without affecting the database):

## 1 ## molecule.Datomic.debugRetract
===================================================================================================================
1      Model(
  1      TxMetaData(
    1      Atom(metaData,user,String,1,Eq(List(Ben Goodman)),None,List(),List())))
------------------------------------------------
2      List(
  1      :db/add     'tx                             :MetaData/user     Values(Eq(List(Ben Goodman)),None)   Card(1))
------------------------------------------------
3      List(
  1      List(
    1      :db.fn/retractEntity   17592186045445
    2      :db.fn/retractEntity   17592186045446
    3      :db/add   #db/id[:db.part/tx -1000097]    :MetaData/user     b                                    Card(1)))
===================================================================================================================

eids: Iterable of entity ids of type Long
txMetaDataMolecules: Zero or more transaction meta data molecules
conn: Implicit Conn value in scope
returns: Unit (prints to output)

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implicit final def long2Entity(id: Long)(implicit conn: Conn): Entity
Long -> Entity api implicit.
Long -> Entity api implicit.

Convenience implicit to allow calling Entity methods directly on entity Long value.
```
// Get entity id of Ben
val benId = Person.e.name_("Ben").get.head

// Retract Ben entity directly on his entity id
benId.retract
```
id
Entity id of type Long
conn
Implicit Conn value in scope
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def retract(eids: Iterable[Long], txMetaDataMolecules: MoleculeBase*)(implicit conn: Conn): TxReport
Retract multiple entities with optional transaction meta data.
Retract multiple entities with optional transaction meta data.

0 or more transaction meta data molecules can be asserted together with a retraction of entities.

Here we retract two comment entities with transaction meta data asserting that the retraction was done by Ben Goodman:
```
retract(Seq(commentEid1, commentEid2), MetaData.user("Ben Goodman"))
```
We can then later see what comments Ben Goodman retracted (op_(false)):
```
Comment.e.text.op_(false).Tx(MetaData.user_("Ben Goodman")).getHistory === List(
  (commentEid1, "I like this"),
  (commentEid2, "I hate this")
)
```
eids
Iterable of entity ids of type Long
txMetaDataMolecules
Zero or more transaction meta data molecules
conn
Implicit Conn value in scope
returns
TxReport with result of retract
See also
Manual | Test
def retractAsync(eids: Iterable[Long], txMetaDataMolecules: MoleculeBase*)(implicit conn: Conn, ec: ExecutionContext): Future[TxReport]
Asynchronously retract multiple entities with optional transaction meta data.
Asynchronously retract multiple entities with optional transaction meta data.

0 or more transaction meta data molecules can be asserted together with a retraction of entities.

Here we asynchronously retract two comment entities with transaction meta data asserting that the retraction was done by Ben Goodman:
```
retractAsync(Seq(commentEid1, commentEid2), MetaData.user("Ben Goodman"))
```
We can then later see what comments Ben Goodman retracted (op_(false)):
```
Comment.e.text.op_(false).Tx(MetaData.user_("Ben Goodman")).getHistory === List(
  (commentEid1, "I like this"),
  (commentEid2, "I hate this")
)
```
eids
Iterable of entity ids of type Long
txMetaDataMolecules
Zero or more transaction meta data molecules
conn
Implicit Conn value in scope
returns
TxReport with result of retract
See also
Manual | Test
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EntityOps

trait EntityOps extends AnyRef

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trait EntityOps extends AnyRef

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EntityOps