PyEOQ 2

*Hint: this is about EOQ 2. The actual version is EOQ3: https://gitlab.com/eoq

PyEOQ is a Python implementation of EOQ (version 2, depricated). PyEOQ provides the full implementation of queries, commands, results and events. In addition, PyEOQ supports local Domains operating on single ECORE XMI files or Workspace composed of several ECORE XMI files.

PyEOQ is based on pyecore a Python-based implementation of the ECORE model of the Eclipse modelling framework.

Contents

• eoq1: The runtime library implementing EOQ version 1. This is every thing needed to use EOQ 1. (Depricated!)
• eoq2: The runtime library implementing EOQ version 2. This is every thing needed to use EOQ 2.
• Examples: Example scripts that demonstrate using PyEOQ.
• Test: Test scripts for PyEOQ, e.g. unit tests.
• Models: Meta-model sorces and generation scripts for the Workspace MDB and XML resource model

EOQ

Essential Object Query (EOQ) is a language to interact remotely and efficiently with object-oriented models, i.e. domain-specific models. It explicitly supports the search for patterns, as used in model transformation languages. Its motivation is an easy to parse and deterministically behaving query structure, but as high as possible efficiency and flexibility. EOQ’s capabilities and semantics are similar to the Object-Constraint-Language (OCL), but it supports in addition transactional model modification, change events, and error handling.

Main Repository: https://gitlab.com/eoq/essentialobjectquery

EOQ user manual: https://gitlab.com/eoq/doc

Installation as pip Package

The latest releases of the PyEOQ runtimes are available on PyPI as a packages and can be installed with pip.

python -m pip install eoq1
python -m pip install eoq2

Getting Started Example

(This example is available as pyeoq/Examples/WhyWarehouseExample.py)

Imagine having the following hierarchically organized domain-specific model of you warehouse?

                                                      _______________
 ___________              _______________            |    Article    |
| Warehouse | categories |   Category    |  articles |---------------|
|-----------|<>--------->|---------------|<>-------->| name : string |
|           |           *| name : string |          *| price : real  |
|___________|        o-->|_______________|<>-o       | sells : int   |
                     |  *                    |       |_______________|
                     o-----------------------o
                           categories

Import eoq2:

from eoq2.mdb.pyecore import PyEcoreSingleFileMdbProvider,PyEcoreMdbAccessor,PyEcoreIdCodec
from eoq2.domain.local import LocalMdbDomain
from eoq2 import Get,Set 
from eoq2 import Cls,Pth 

Initialize a local domain with the warehouse user and meta-model:

mdbProvider = PyEcoreSingleFileMdbProvider('Workspace/GeneralStore.warehouse',"Workspace/Meta/warehouse.ecore")
valueCodec = PyEcoreIdCodec() #create the default value codec that converts objects to #IDs
mdbAccessor = PyEcoreMdbAccessor(mdbProvider.GetMdb(),valueCodec)
domain = LocalMdbDomain(mdbAccessor)
mdbProvider.CoupleWithDomain(domain, valueCodec)

Would you like to get a list of articles?

articles = domain.Do( Get( Cls('Article') ) )

Would you like to know which one is sold less than 3-times?

badArticles = domain.Do( Get( Cls('Article').Sel(Pth('sells').Les(3)) ) )

You might want to reduce their price by 10%?

domain.Do( Set( 
    Cls('Article').Sel(Pth('sells').Les(3)),
    'price',
    Cls('Article').Sel(Pth('sells').Les(3)).Pth('price').Mul(0.9) 
) )

Would you like to see a list of the names of the categories of the badly selling articles sorted ascendingly?

badCategories = domain.Do( Get( Cls('Article').Sel(Pth('sells').Les(3)).Met('PARENT').Pth('name').Uni([]).Idx('SORTASC') ) )

List of EOQ Commands

PyEOQ supports the follwing list of EOQ commands. For more details see here.

List of EOQ Queries Segments

PyEOQ supports the follwing set of EOQ query segments. For more details see here.