Friday, 8 July 2011

Custom Apex Maps - step by step

The cool thing about receiving a complicated requirement is that you learn something new and it turns out to be pretty cool.

In an application I needed to be able to display ocean ports on a map along with the number of shipments shipped from that port. Here is what the map looked like once I was done:


Well, that sounds easy enough! However, the maps that come with AnyChart's anymap in Apex 4, know nothing about ocean ports. The map like the one above has cities in the map information but those cities are not located exactly where the ports are located, nor do they have the same name as the port. The image of the map is exactly as I want it, but I need a set of custom locations to display on the map.

Let's get started.....

I decided to start by creating a collection on my page that would get the information I require from the customer's shipping data. I need the list of ports and the number of shipments per port.  Here is my code to create the collection.

declare
    l_query   varchar2(4000);
begin
  
     IF apex_collection.collection_exists(p_collection_name=>'CHINAMAP') then

        APEX_COLLECTION.DELETE_COLLECTION(
           p_collection_name => 'CHINAMAP' );

     END IF;


    l_query := q'(select null LINK, )';
    l_query := l_query || q'(port_of_load LABEL, )';
    l_query := l_query || q'(count(shipment_id) SHIPMENTS )';
    l_query := l_query || q'(from shipping_rep_sum )';
    l_query := l_query || q'(where export_country = 'China' )';
    l_query := l_query || q'(and main_carriage = 'OCEAN' )';
    l_query := l_query || q'(group by port_of_load)';

    apex_collection.create_collection_from_query (
        p_collection_name => 'CHINAMAP',
        p_query => l_query,
        p_generate_md5 => 'YES');
 
end;

And here is the resulting collection data:


If you were trying to display the above collection data on a map of China, it wouldn't work. The majority of the port names have no associated locations on the map.

Next I created a table that stores the longitude and latitude of the ports (I looked up these figures on the internet. The table data looks like this:


So far....so good. I've got my customer data, and I have the coordinates for the locations. Now, I need to be able to supply the map with the data in the right format. The map uses xml to plot the locations. I need to pass data to the map in a format that will look like this:

<data>
<series name="Ports" type="Marker" palette="Default" >
<point name="Ningbo" x="121.55" y="29.88" >
    <attributes>
       <attribute name="value1">23</attribute>
</attributes>
</point>
<point name="Qingdao" x="120.3575" y="36.093" >
    <attributes>
       <attribute name="value1">45</attribute>
</attributes>
</point>
<point name="Shekou" x="112.90" y="21.48" >
    <attributes>
       <attribute name="value1">2</attribute>
</attributes>
</point>
<point name="Nhava Sheva" x="72.97" y="18.95" >
    <attributes>
       <attribute name="value1">2</attribute>
</attributes>
</point>
<point name="Shanghai" x="121.375" y="31.254" >
    <attributes>
       <attribute name="value1">167</attribute>
</attributes>
</point>
<point name="Yantian" x="116.27" y="23.60" >
    <attributes>
       <attribute name="value1">3</attribute>
</attributes>
</point>
<point name="Hong Kong" x="119.17" y="25.27" >
    <attributes>
       <attribute name="value1">1</attribute>
</attributes>
</point>
</series>
</data>

I create a hidden text area on the page. In my case, I called it P6_XML_CHINA. Then I have an on load pl/sql process to generate the xml and populate the hidden item.  Here's my process code:
declare
    l_data      varchar2(4000);
    v_xlocation varchar2(50);
    v_ylocation varchar2(50);
    v_port      varchar2(100);

    cursor get_locations is select x_location
                                  ,y_location
                             from port_locations
                             where port_name = v_port;
begin
    l_data := '<data>'||chr(10);
    l_data := l_data ||'<series name='||chr(34)||'Ports'||chr(34)||' type='||chr(34)||'Marker'||chr(34)||' palette='||chr(34)||'Default'||chr(34)||' >'||chr(10);
  
 
     for c1 IN (select c002,c003
                from apex_collections
                where collection_name = 'CHINAMAP')


     loop
            v_port := c1.c002;
            v_xlocation  := null;
            v_ylocation  := null;
            open get_locations;
            fetch get_locations into v_xlocation, v_ylocation;
            close get_locations;

            if v_xlocation is not null
            then
               l_data := l_data ||'<point name='||chr(34)||c1.c002||chr(34)||' ';
               l_data := l_data ||'x='||chr(34)||v_xlocation||chr(34)||' ';
               l_data := l_data ||'y='||chr(34)||v_ylocation||chr(34)||' >'||chr(10);
               l_data := l_data ||'    <attributes>'||chr(10);
               l_data := l_data ||'       <attribute name='||chr(34)||'value1'||chr(34)||'>';
               l_data := l_data ||c1.c003||'</attribute>'||chr(10);
               l_data := l_data ||'</attributes>'||chr(10);
               l_data := l_data||'</point>'||chr(10);  

            end if;
          
      end loop;

      l_data := l_data ||'</series>'||chr(10);
      l_data := l_data ||'</data>';

       :p6_xml_china := l_data;

end;

Next, I create a map region and select a map of China. I set all of the map attributes the way I want them and apply the changes. I then edit the map and select the "map xml" tab and set "Use customer xml" to 'Yes'.  This displays the xml that the map will use. I need to edit the xml slightly.  Scroll down until you find the reference #DATA# and replace it with a reference to the hidden item with &P6_XML_CHART. (remember the period at the end). This will tell the map to use the xml stored in the hidden item which will plot all of the custom points.

You can plot anything on a map as long as you can supply the associated longitude and the latitude and prepare the required xml.

Customer map done!  Cool stuff learned!

7 comments:

  1. Bruce,

    Thanks for your post - this is really fascinating to me (I haven't delved too deeply into customizing charts or creating collections yet)!

    I wanted to point out that some features of the XDB could assist you (so you don't have to create the XML by hand). DBMS_XMLGEN comes to mind, but I'm sure you're aware there is more than one way to accomplish almost anything in Oracle.

    Regards,

    -Kris

    ReplyDelete
  2. Thanks for your explaination on this. I have added some information on the generating of the custom XML from SQL as suggested by Kris at
    http://ascendoracle.blogspot.com/2011/07/generating-xml-from-sql-for-apex-map.html

    ReplyDelete
  3. Hi,
    I am new to APEX, how do you add a hidden item to a page?

    Lisa

    ReplyDelete
  4. Hi Bruce,

    It was very useful and I was trying this, however I could not see points on map.
    Could you please let me know where in apex I need to include PL/SQL block ?

    Thanks,
    Girish

    ReplyDelete
  5. Hi can you please explain clearly how to develop above case. i am new to apex. i want to develop map charts like above map with multiple markers. If it possible please explain with screen shots. it will very useful to me.please help me someone. thanks

    ReplyDelete
  6. That is excellent. I was wondering if there is a way to add custom maps apart from the maps provided by AnyChart.

    Any advise would be greatly appreciated.

    Thanks
    Kishor

    ReplyDelete
  7. Hi Bruce,

    Could you please let me know where we need to create collection that mentioned above ?

    Looking for response

    ReplyDelete