com.screenscraper.datamanager.sql.util

Class SqlPkLookup

java.lang.Object

com.screenscraper.datamanager.sql.util.SqlPkLookup

public class SqlPkLookup
extends java.lang.Object

A class that is simplifies looking up primary keys based on a number of constraints. It is a wrapper that simplifies the SqlLookup class to return a List of matching primary keys for the specified table. This class is very similar to the SqlDuplicateFilter class, however, it is designed so the developer can easily retrieve data that may be required in the scraping process. For example if the developer is trying to determine if he needs to scrape a certain page from a list of search results he could build an SqlPkLookup based on the information on the search results page to determine if the data has already been scraped. The developer can use this information to reduce the number of requests on websites with redundant data. The SqlDuplicateFilter, on the other hand, would require scraping all the data then when DataManager.flush is called it would perform the lookup and filter/supplement duplicate records.

Example usage: //look up a real estate listing based its brokers name and the listing address SqlPkLookup lookup = new SqlPkLookup(dm, "listings"); lookup.addConstraint("brokers", "lastname", dataRecord.get("LASTNAME")); lookup.addConstraint("brokers", "firstname", dataRecord.get("FIRSTNAME")); lookup.addConstraint("listings", "address", dataRecord.get("ADDRESS")); lookup.addConstraint("listings", "address2", dataRecord.get("ADDRESS2")); lookup.addConstraint("listings", "zipcode", dataRecord.get("ZIPCODE")); List matches = lookup.execute(); if(matches.size()==0) session.scrapeFile("Details");

Constructor Summary

Constructors

Constructor and Description
SqlPkLookup(SqlDataManager dm, java.lang.String table)

Method Summary

Modifier and Type	Method and Description
void	addConstraint(java.lang.String table, java.lang.String column, java.lang.Object value) add a constraint to the lookup.
java.util.List<java.util.Map<java.lang.String,DataObject>>	execute() exete the lookup
void	setLimit(int limit) Limit the number of results to return.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

SqlPkLookup

public SqlPkLookup(@NotNull
                   SqlDataManager dm,
                   java.lang.String table)

Parameters:

dm - The data manager

table - The table

Method Detail

setLimit

public void setLimit(int limit)

Limit the number of results to return. Setting will greatly improve the efficiency of the lookup.

Parameters:

limit -

addConstraint

public void addConstraint(java.lang.String table,
                          java.lang.String column,
                          java.lang.Object value)
                   throws java.io.UnsupportedEncodingException

add a constraint to the lookup. This translates into a "WHERE" in your query.

Parameters:

table -

column -

Throws:

java.io.UnsupportedEncodingException

execute

@NotNull
public java.util.List<java.util.Map<java.lang.String,DataObject>> execute()
                                                                             throws java.io.UnsupportedEncodingException

exete the lookup

Returns:

a List of results that matches. Each individual result is a Map of the pk column name and its corresponding value.

Throws:

java.io.UnsupportedEncodingException