From 98f42001cc86bd79d2b5877d04cfc3b10080ca05 Mon Sep 17 00:00:00 2001
From: Dan Stillman <dstillman@zotero.org>
Date: Sat, 3 Jun 2006 20:23:19 +0000
Subject: [PATCH] New function Scholar.getRandomID( table, column [, max] ) for
 getting unique random keys in a DB table, because auto_increments make me
 feel dirty -- max is optional and defaults to 16383 (which should store in 2
 bytes in SQLite), but increases automatically if a unique id can't be found
 after 10 tries

---
 .../content/scholar/xpcom/scholar.js          | 35 +++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/chrome/chromeFiles/content/scholar/xpcom/scholar.js b/chrome/chromeFiles/content/scholar/xpcom/scholar.js
index 25009ccb9..cb11a5899 100644
--- a/chrome/chromeFiles/content/scholar/xpcom/scholar.js
+++ b/chrome/chromeFiles/content/scholar/xpcom/scholar.js
@@ -22,6 +22,7 @@ var Scholar = new function(){
 	this.flattenArguments = flattenArguments;
 	this.join = join;
 	this.randomString = randomString;
+	this.getRandomID = getRandomID;
 	
 	this.Hash = Hash;
 	
@@ -200,6 +201,40 @@ var Scholar = new function(){
 	}
 	
 	
+	/**
+	* Find a unique random id for use in a DB table
+	**/
+	function getRandomID(table, column, max){
+		if (!table){
+			throw('SQL query not provided');
+		}
+		
+		if (!column){
+			throw('SQL query not provided');
+		}
+		
+		var sql = 'SELECT COUNT(*) FROM ' + table + ' WHERE ' + column + '=';
+		
+		if (!max){
+			max = 16383;
+		}
+		
+		var tries = 10; // # of tries to find a unique id
+		do {
+			// If no luck after number of tries, try a larger range
+			if (!tries){
+				max = max * 2;
+			}
+			var rnd = Math.floor(Math.random()*max);
+			var exists = Scholar.DB.valueQuery(sql + rnd);
+			tries--;
+		}
+		while (exists);
+		
+		return rnd;
+	}
+	
+	
 	/*
 	 * Class for creating hash arrays that behave a bit more sanely
 	 *