Use OrientDB to persistently store dynamic Ruby-Objects and use database queries to manage even very large datasets.
The Package ist tested with Ruby 2.2.1 and Orientdb 2.1.
To start you need a ruby 2.x Installation and a working OrientDB-Instance.
Install the Gem the usual way
For a quick start, go to the home directory of the package and start an irb-session
require 'bundler/setup'
require 'active-orient'First, the Database-Server has to be specified. Then we can connect to a database. Assuming, the server is located on localhost, we just define »default-server«
ActiveOrient::OrientDB.default_server= { user: 'your user', password: 'your password' }
r = ActiveOrient::OrientDB.new database: 'First'
=> I, [2015-08-18T09:49:18.858758 #88831] INFO -- OrientDB#Connect: Connected to database First
=> #<ActiveOrient::OrientDB:0x000000048d0488 @res=#<RestClient::Resource:0x00000004927288
@url="http://localhost:2480", @block=nil,
@options={:user=>"xx", :password=>"***"}>, @database="First", @classes=[]> »r« is the Database-Instance itself. Obviously the database is empty.
Let's create some classes
M = r.open_class 'classname' #
M = r.create_class 'classname' # creates or opens a basic document-class
M = r.create_vertex_class 'classname' # creates or opens a vertex-class
M = r.create_edge_class 'classname' # creates or opens an edge-class, providing bidirectional links between documents
r.delete_class M # universal removal-of-the-class-method»M« is the ActiveOrient::Model-Class itself, a constant pointing to the class-definition of the ruby-class. Its a shortcut for »ActiveOrient::Model::{Classname} and is reused if defined elsewhere.
If a schema is used, properties can be created and retrieved as well
r.create_properties( M ) do
{ symbol: { propertyType: 'STRING' },
con_id: { propertyType: 'INTEGER' },
details: { propertyType: 'LINK', linkedClass: 'Contracts' }
}
r.get_class_properties M or
M.create_property 'symbol'
M.create_property 'con_id', type: 'integer'
M.create_property 'details', type: 'link', other_class: 'Contracts'Every OrientDB-Database-Class is mirrord as Ruby-Class. The Class itself is defined by
M = r.create_class 'classname'
M = r.create_class { superclass_name: 'classname' }
Vertex = r.create_vertex_class 'classname'
Edge = r.create_edge_class 'classname' and is of TYPE ActiveOrient::Model::{classname}
As for ActiveRecord-Tables, the Class itself provides methods to inspect and to filter datasets form the database.
M.all
M.first
M.lastreturns an Array containing all Documents/Edges of the Class; the first and the last Record.
M.where town: 'Berlin'performs a query on the class and returns the result as Array
M.count where: { town: 'Berlin' }gets the number of datasets fullfilling the search-criteria. Any parameter defining a valid SQL-Query in Orientdb can be provided to the count, where, first and last-method.
A »normal« Query is submitted via
M.get_documents projection: { projection-parameter }
distinct: { some parameters }
where: { where-parameter }
order: { sorting-parameters }
group_by: { one grouping-parameter}
unwind:
skip:
limit:
# or
query = OrientSupport::OrientQuery.new {paramter}
M.get_documents query: queryBasic graph-support:
vertex_1 = Vertex.create color: "blue"
vertex_2 = Vertex.create flower: "rose"
Edge.create_edge attributes: { :birthday => Date.today }, from: vertex_1, to: vertex_2connects the vertices and assigns the attributes to the edge
A record in a database-class is defined by a »rid«. Every Model-Object comes with a handy »link«-method.
In OrientDB links are used to realise unidirectional 1:1 and 1:n relationships.
ActiveOrient autoloads Model-objects when they are accessed. As a consequence, if an Object is stored in Cluster 30 and id 2, then "#30:2" fully qualifies the ActiveOrient::Model object.
TestLinks = r.create_class 'Test_link_class'
TestBase = r.create_class 'Test_base_class'
link_document = TestLinks.create att: 'one attribute'
base_document = TestBase.create base: 'my_base', single_link: link_document base_document.single_link just contains the rid. When accessed, the ActiveOrient::Model::Testlinkclass-object is autoloaded and
base_document.single_link.attreads the stored content of link_document.
To store a list of links to other Database-Objects a simple Array is allocated
# predefined linkmap-properties
base_document = TestBase.create links: []
( 0 .. 20 ).each{ |y| base_document.links << TestLinks.create nr: y }
end
#or in schemaless-mode
base_document = TestBase.create links: (0..20).map{|y| TestLinks.create nr: y }
base_document.links behaves like a ruby-array.
If you got an undirectional graph
a --> b ---> c --> d
the graphelements can be explored by joining the objects ( a.b.c.d ), or (a.b[5].c[9].d )
Edges are easily handled
Vertex = r.create_vertex_class 'd1'
Eedge = r.create_edge_class 'e1'
start = Vertex.create something: 'nice'
the_end = Vertex.create something: 'not_nice'
the_edge = Edge.create_edge attributes: { transform_to: 'very bad' },
from: start,
to: the_end
(...)
the_edge.deleteThere is a basic support for traversals throught a graph. The Edges are accessed by their names (downcase).
start.e1[0]
--> #<ActiveOrient::Model::E1:0x000000041e4e30
@metadata={"type"=>"d", "class"=>"E1", "version"=>60, "fieldTypes"=>"out=x,in=x",
"cluster"=>16, "record"=>43},
@attributes={"out"=>"#31:23", "in"=>"#31:15", "transform_to"=>"very bad" }>The Attributes "in" and "out" can be used to move across the graph
start.e1[0].out.something
---> "not_nice
start.e1[0].in.something
---> "niceContrary to traditional SQL-based Databases OrientDB handles subqueries very efficient. In addition, OrientDB supports precompiled statements (let-Blocks).
ActiveOrient is equipped with a simple QueryGenerator: ActiveSupport::OrientQuery. It works in two modi: a comprehensive and a subsequent one
q = OrientSupport::OrientQuery.new
q.from = Vertex # If a constant is used, then the correspending
# ActiveOrient::Model-class is refered
q.where << a: 2
q.where << 'b > 3 '
q.distinct = :profession
q.order = { :name => :asc }is equivalent to
q = OrientSupport::OrientQuery.new from: Vertex ,
where: [{ a: 2 }, 'b > 3 '],
distinct: :profession,
order: { :name => :asc }
q.to_s
=> select distinct( profession ) from Vertex where a = 2 and b > 3 order by name ascBoth modes can be mixed.
If subqueries are nessesary, they can be introduced as OrientSupport::OrientQuery or as »let-block«.
OQ = OrientSupport::OrientQuery
q = OQ.new from: 'ModelQuery'
q.let << "$city = adress.city"
q.where = "$city.country.name = 'Italy' OR $city.country.name = 'France'"
q.to_s
=> select from ModelQuery let $city = adress.city where $city.country.name = 'Italy' OR $city.country.name = 'France' or
q = OQ.new
q.let << { a: OrientSupport::OrientQuery.new( from: '#5:0' ) }
q.let << { b: OrientSupport::OrientQuery.new( from: '#5:1' ) }
q.let << '$c= UNIONALL($a,$b) '
q.projection << 'expand( $c )'
q.to_s
=> select expand( $c ) let $a = ( select from #5:0 ), $b = ( select from #5:1 ), $c= UNIONALL($a,$b)or
OpenInterest = r.open_class 'Openinterest'
last_12_open_interest_records = OQ.new from: OpenInterest, order: { fetch_date: :desc } , limit: 12
bunch_of_contracts = OQ.new from: last_12_open_interest_records, projection: 'expand( contracts )'
distinct_contracts = OQ.new from: bunch_of_contracts, projection: 'expand( distinct(@rid) )'
distinct_contracts.to_s
=> "select expand( distinct(@rid) ) from ( select expand( contracts ) from ( select from Openinterest order by fetch_date desc limit 12 ) ) "
cq = r.get_documents query: distinct_contractsSql-commands can be executed as batch
The ActiveOrient::Query-Class provides a Query-Stack and an Records-Array which keeps the results. The ActiveOrient::Query-Class acts as Parent-Class for aggregated Records (without a @rid), which are ActiveOrient::Model::Myquery Objects. If a Query returns a database-record, the correct ActiveOrient::Model-Class is instantiated.
ach = ActiveOrient::Query.new
ach.queries << 'create class Contracts ABSTRACT'
ach.queries << 'create property Contracts.subcategory link'
ach.queries << 'create property Contracts.details link'
ach.queries << 'create class Stocks extends Contracts'
ach.queries << 'create class Futures extends Contracts'
result = ach.execute_queries transaction: false
queries the database as demonstrated above. In addition, the generated query itself is added to the »queries«-Stack and the result can be found in sample_query.records.
This feature can be used as a substitute for simple functions
roq = ActiveOrient::Query.new
roq.queries =["select name, categories.subcategories.contracts from Industries where name containstext …'ial'"]
roq.execute_queries.each{|x| puts x.name, x.categories.inspect }
--> Basic Materials [["#21:1"]]
--> Financial [["#21:2"]]
--> Industrial [["#23:0", "#23:1"]]OrientDB supports the execution of SQL-Batch-Commands. ( http://orientdb.com/docs/2.0/orientdb.wiki/SQL-batch.html ) This is supported simply by using a Array as Argument for ActiveOrient::Query.queries
Therefor complex queries can be simplified using database-variables
ach = ActiveOrient::Query.new
ach.queries << [ "select expand( contracts ) from Openinterest"
"let con = select expand( contracts ) from Openinterest; ",
"...", ... ]
result = ach.execute_queries The contract-documents are accessible with
r.get_document '21:1'
--><Stocks: con_id: 77680640 currency: EUR details: #18:1 exchange: SMART local_symbol: BAS
primary_exchange: IBIS subcategory: #14:1 symbol: BAS>or
my_query = ActiveOrient::Query.new
['Contracts', 'Industries', 'Categories', 'Subcategories'].each do |table|
my_query.queries = [ "select count(*) from #{table}"]
count = my_query.execute_queries
# count=> [#<ActiveOrient::Model::Myquery:0x00000003b317c8
# @metadata={"type"=>"d", "class"=>nil, "version"=>0, "fieldTypes"=>"count=l"},
# @attributes={"count"=>4 } ] --> an Array with one Element, therefor count.pop
puts "Table #{table} \t #{count.pop.count} Datasets "
end
-->Table Contracts 56 Datasets
-->Table Industries 8 Datasets
-->Table Categories 22 Datasets
-->Table Subcategories 35 Datasets Note that the fetched Object is of type »Stocks« (ActiveOrient::Model::Stocks).
The ActiveOrient-API documentation can be found here: https://github.com/orientechnologies/orientdb-docs/wiki/OrientDB-ActiveOrient and the ActiveModel-documentation is here: http://www.rubydoc.info/gems/activemodel
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