com.neurosys.odb.document.etl

Class ODBQueryTransformer<E>

java.lang.Object

com.neurosys.odb.etl.ODBQueryTransformer<E,com.orientechnologies.orient.core.record.impl.ODocument>

com.neurosys.odb.document.etl.ODBQueryTransformer<E>

Type Parameters:

E - as entity type

E - as input Entity type

T - as return type

All Implemented Interfaces:

QueryTransformer, UpdatableContext<com.orientechnologies.orient.core.db.OPartitionedDatabasePool>, Serializable, Function<E,List<com.orientechnologies.orient.core.record.impl.ODocument>>, org.apache.commons.collections.Transformer

public class ODBQueryTransformer<E>
extends ODBQueryTransformer<E,com.orientechnologies.orient.core.record.impl.ODocument>

Orientdb query transformer : Fire any OrientDb SQL query and return the records stored in database.

Input types to transformer : Transformer accepts inputs of type Object[] or Collection or Map or PageInfo.

Any params supplied in the form of Collection will be converted to an Object[]. Any params supplied will be applied sequentially if the input is an Object[] or a List One can provide PageInfo as the input itself or last param in the parameter Array; if pagination is required One can provide a Map to this Transformer. When a Map is passed then Query parameters are the "Keys" passed in this Map.

• Any value thats associated as a PageInfo will be used to set the PageSize and other page related information to the Query. and in Query its parameter name will be same as dataMemberName of PageInfo class.
• For Eg : if 'PageInfo.recordNumber' is to be used to set value in Query, then its parameter in Query will be ':recordNumber' and similarly for 'PageInfo.pageSize' it will be 'pageSize'

If the input is not an Array, List, Map or PageInfo BUT a "fieldMapping" is provided then map from query param name to field name or Transformer that will act on input to get param value

Structure of Prepared Queries :

In Orientdb, Prepared queries use two kinds of markers to substitute parameters on execution '?' Syntax is used in reference to position parameters. For instance : OSQLSynchQuery<ODocument> query = new OSQLSynchQuery<ODocument>("SELECT FROM Profile WHERE name = ? AND surname = ?"); ':paramName' Syntax is used in reference to named parameters. For instance : OSQLSynchQuery<ODocument> query = new OSQLSynchQuery<ODocument>("SELECT FROM Profile WHERE name = :name AND surname = :surname"); It is to be Noted that, ':paramName' consisting of only numerics or a combination of numerics and special characters only, are not supported (eg= ':1' or or ':?1')

Functions to query from database :

ODatabaseDocument provides some methods to interact with the database via SQL statements and scripts. 'query()' method are intended to execute idempotent statements only (eg. SELECT, MATCH, TRAVERSE). 'command()' methods can execute any type of statements, idempotent (SELECT, MATCH...), non idempotent (INSERT, UPDATE, DELETE...) and DDL (CREATE CLASS, CREATE PROPERTY...) Reference Link

Reference Links related to Querying in Orientdb Java Querying API for Orientdb Pagination in Orientdb Prepared Queries in Orientdb Querying Documents Neurosys Documentation on Querying from database

TODO : Remove deprecation from 'db.query()' when sending OSQLSynchQuery or OSQLAsynchQuery as parameter. No such non deprecated solution was available when last checked. Refer to neurosys doc here

Author:

Nitin Sharma, Anubhav Bhargava

, Arjun Dhar

See Also:

UpdatableContext, Transformer, OResultSet, StackOverFlow : Link for question asked on stackoverflow related to research on whether query requires a param., Serialized Form