escape null values(Nestoria UK) - php

Question

I am able to retrieve data from a website(Nestoria) and store into my PostGIS database. However not every individual result that is returned have latitude and longitude values and as such they are not stored into the database. I tried using (pg_escape_string) so that it can return null values as double quotes(") but it didn't work. The field type of my lat and long columns in the database is "double precision".
This is a sample output of the error: ("Warning: pg_query() [function.pg-query]: Query failed: ERROR: invalid input syntax for type double precision: "" LINE 1: ...droom garden flat set in a period building with...', '', '') ^ in C:\XAMMP...\database.php on line 12")
Please see the code below for retrieving the data:
<?php
$url = ("http://api.nestoria.co.uk/api?action=search_listings&centre_point=51.5424,-0.1734,2km&listing_type=rent&property_type=all&price_min=min&price_max=max&bedroom_min=0&bedroom_max=0&number_of_results=50&has_photo=1&page=4");
$xml = simplexml_load_file($url);
foreach ($xml->response->listings as $entry) {
echo $entry->attributes()->title;
echo $entry->attributes()->bathroom_number;
echo $entry->attributes()->bedroom_number;
echo $entry->attributes()->datasource_name;
echo $entry->attributes()->guid;
echo $entry->attributes()->img_url;
echo $entry->attributes()->keywords;
echo $entry->attributes()->lister_name;
echo $entry->attributes()->listing_type;
echo $entry->attributes()->price;
echo $entry->attributes()->price_type;
echo $entry->attributes()->property_type;
echo $entry->attributes()->summary;
echo $entry->attributes()->latitude;
echo $entry->attributes()->longitude;
// Process XML file
}
?>
Find below the code to store values into database:
<?php
require 'nestoriauk.php';
// Opens a connection to a PostgresSQL server
$connection = pg_connect("dbname=postgis user=postgres password=xxxx");
// Execute query
foreach ($xml->response->listings as $entry) {
$query = "INSERT INTO nestoriaphp(title, bathroom, bedroom, datasource, guid, image, keywords, lister, listype, price, pricetype, property_type, summary, latitude, longitude) VALUES ('" . pg_escape_string($entry->attributes()->title) . "', '" . pg_escape_string($entry->attributes()->bathroom_number) . "', '" . pg_escape_string($entry->attributes()->bedroom_number) . "', '" . pg_escape_string($entry->attributes()->datasource_name) . "', '" . pg_escape_string($entry->attributes()->guid) ."', '" . pg_escape_string($entry->attributes()->img_url) . "', '" . pg_escape_string($entry->attributes()->keywords) . "', '" . pg_escape_string($entry->attributes()->lister_name) . "', '" . pg_escape_string($entry->attributes()->listing_type) . "', '" . pg_escape_string($entry->attributes()->price) . "', '" . pg_escape_string($entry->attributes()->price_type) . "', '" . pg_escape_string($entry->attributes()->property_type) ."', '" . pg_escape_string($entry->attributes()->summary) . "', '" . pg_escape_string($entry->attributes()->latitude) . "', '" . pg_escape_string($entry->attributes()->longitude) . "')";
$result = pg_query($query);
printf ("These values are inserted into the database - %s %s %s", $entry->attributes()->title, $entry->attributes()->bathroom_number, $entry->attributes()->bedroom_number, $entry->attributes()->datasource_name, $entry->attributes()->guid, $entry->attributes()->img_url, $entry->attributes()->keywords, $entry->attributes()->lister_name, $entry->attributes()->listing_type, $entry->attributes()->price, $entry->attributes()->price_type, $entry->attributes()->property_type, $entry->attributes()->summary, $entry->attributes()->latitude, $entry->attributes()->longitude);
}
pg_close();
?>
Yemi

Answer 1

If a POI has no lat-lon, which value it has? empty string?
assuming that an empty string is returned when there is no lat-lon.
$lon = "NULL";
if($entry->attributes()->longitude != "")
$lon = "'".$entry->attributes()->longitude."'";
$lat = "NULL";
if($entry->attributes()->latitude != "")
$lat = "'".$entry->attributes()->latitude."'";
so query looks like this:
$query = "INSERT INTO nestoriaphp(title, bathroom, bedroom, datasource, guid, image, keywords, lister, listype, price, pricetype, property_type, summary, latitude, longitude) VALUES ('" . pg_escape_string($entry->attributes()->title) . "', '" . pg_escape_string($entry->attributes()->bathroom_number) . "', '" . pg_escape_string($entry->attributes()->bedroom_number) . "', '" . pg_escape_string($entry->attributes()->datasource_name) . "', '" . pg_escape_string($entry->attributes()->guid) ."', '" . pg_escape_string($entry->attributes()->img_url) . "', '" . pg_escape_string($entry->attributes()->keywords) . "', '" . pg_escape_string($entry->attributes()->lister_name) . "', '" . pg_escape_string($entry->attributes()->listing_type) . "', '" . pg_escape_string($entry->attributes()->price) . "', '" . pg_escape_string($entry->attributes()->price_type) . "', '" . pg_escape_string($entry->attributes()->property_type) ."', '" . pg_escape_string($entry->attributes()->summary) . "', " . $lat . ", " . $lon . ")";
Note that the NULL value has no '' in sql.