In Google App Engine, you can create owned one-to-many relationships between entities. The classic example you were taught at uni is that a Book owns a Chapter, which in turn, owns a Paragraph. For my site, stolencamerafinder, the example is that a camera Make owns a set of Models. If you want to query for ...

In Google App Engine, you can create owned one-to-many relationships between entities. The classic example you were taught at uni is that a Book owns a Chapter, which in turn, owns a Paragraph. For my site, stolencamerafinder, the example is that a camera Make owns a set of Models.

If you want to query for the model directly in GQL (from the app engine dashboard for example) you can create the key by specifying the full parent chain:

SELECT * FROM Model where __key__ = KEY('Make', 'canon', 'Model', 'canon eos 5d')

Google’s GQL reference was a little sparse on this syntax so I’m posting it here in the hope you find this faster than I worked it out.

For completeness, this is the difference it makes in JDO. My old code looked something like this:

PersistenceManager pm = PMF.get().getPersistenceManager();
Key makeKey = KeyFactory.createKey(Make.class.getSimpleName(), makeName);
Make make = pm.getObjectById(Make.class, key);
List<Model> models = make.getModels();

for (Model model : models) {
    if (model.getName().equals(modelName)) {
        return model;
    }
}

It doesn’t take much imagination to realise this doesn’t scale very nicely as the number of models increases. The new code looks like this:

PersistenceManager pm = PMF.get().getPersistenceManager();
Key makeKey = KeyFactory.createKey(Make.class.getSimpleName(), makeName);
// Can create the Model key by specifying parent key...
Key modelKey = KeyFactory.createKey(makeKey, Model.class.getSimpleName(), name);
// Bam! Get the child entity in a single query
Model model = pm.getObjectById(Model.class, modelKey);

I wouldn’t have noticed this performance bottle neck if it wasn’t for appwrench. It looks a little dead to be honest, but works well.

I just got this in an email: A friend has asked me to take some of their wedding photos with their Canon 1000D. Had a play with it yesterday and I'm finding the flash a bit harsh. Is there a top tip to minimise this? Firstly, if you're using the camera in the day near natural ...

I just got this in an email:

A friend has asked me to take some of their wedding photos with their Canon 1000D. Had a play with it yesterday and I’m finding the flash a bit harsh. Is there a top tip to minimise this?

Firstly, if you’re using the camera in the day near natural light, the camera will be fine and it’s all down to your artistic flair.

For evening shots, I’ve written a bunch of tips, but really, there is only one:

• Borrow a Canon Speedlite that supports ETTL. (eg, the 430EXii or 580EXii).

Seriously. If you know someone into their photography that may have one you can borrow, give them a ring. Slap it on the camera, press “mode” until it says “ETTL” on the screen, aim the flash so the light bounces of a wall/ceiling to your subject (pool skills handy here) and snap away. The rest of the tips may help prevent you taking a load of unusable shots, but if you get a speedlite, you will take the best shots of the whole day (perhaps including the photographer’s).

If you can’t get a speedlite, my next-best advice is to wait for the sun to come up or get your subject under some other light source. On-camera flash is ugly, and unflattering. I have a top-end Canon and I never use the on-camera flash on people because they’ll just look sweaty and wrinkly. If you can get people next to a lamp or something, you’ll have much more luck.

If neither of those tips will help you, here are what I consider to be “last resort” tips:

• Prop camera against wall or on table for a steadier shot.
• Try self timer with camera on table.
• Form triangles with your body (tuck elbows in to sides) to become human tripod. Remember to look like a pro by cupping the lens with left hand palm upwards.

Anti-tips! Don’t do this:

• Raise the ISO above 800. Ideally, keep the ISO at 400 or lower unless you like grainy photos.
• Stick a Rizla to the flash. It will not soften the light, it just drinks the battery.

Keeping the camera steady will mean sharper shots, but if your subjects move, you’ll still get blurry shots. But I say go with it. Asking people to stay still means awkward faces. A blurry shot of someone laughing / dancing is a good thing if it’s deliberate.

My favourite wedding photos are always in the evening when people are relaxed (read: drunk). I’m sure you’ll capture some gems.

Hmm, you want to add the "lastmod" node, but you're too lazy to ever keep that up to date so you decide to update it with your Ant script whenever you deploy. Easy. So you've just written a valid sitemap.xml file for your website because Google said it was a good idea. Great. <?xml version="1.0" encoding="UTF-8" ...

Hmm, you want to add the “lastmod” node, but you’re too lazy to ever keep that up to date so you decide to update it with your Ant script whenever you deploy. Easy.

So you’ve just written a valid sitemap.xml file for your website because Google said it was a good idea. Great.

1
2
3
4
5
6
7
8

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
   <url>
      <loc>http://www.stolencamerafinder.com/</loc>
      <lastmod>2011-04-21</lastmod>
      <changefreq>weekly</changefreq>
   </url>
</urlset>

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
   <url>
      <loc>http://www.stolencamerafinder.com/</loc>
      <lastmod>2011-04-21</lastmod>
      <changefreq>weekly</changefreq>
   </url>
</urlset>

First, you’ll need the jar for a third-party Ant task called XMLTask. Once you have that, the ant target you’ll need is simply:

1
2
3
4
5
6
7
8
9

<taskdef name="xmltask" classname="com.oopsconsultancy.xmltask.ant.XmlTask" classpath="test-lib/xmltask.jar"/>
<target name="update-sitemap" description="update the update date">
    <tstamp>
        <format property="today" pattern="yyyy-MM-dd" locale="en,UK"/>
    </tstamp>
    <xmltask source="war/sitemap.xml" dest="war/sitemap.xml" standalone="yes" report="true">
        <replace path="/:urlset/:url/:lastmod/text()" withText="${today}"/>
    </xmltask>
</target>

<taskdef name="xmltask" classname="com.oopsconsultancy.xmltask.ant.XmlTask" classpath="test-lib/xmltask.jar"/>
<target name="update-sitemap" description="update the update date">
	<tstamp>
	    <format property="today" pattern="yyyy-MM-dd" locale="en,UK"/>
	</tstamp>
    <xmltask source="war/sitemap.xml" dest="war/sitemap.xml" standalone="yes" report="true">
        <replace path="/:urlset/:url/:lastmod/text()" withText="${today}"/>
    </xmltask>
</target>

Yeah yeah, this is kid’s stuff, why blog about it? Well, embarrassingly, it took me 3 hours of messing around to get it working. If I don’t write it down somewhere, I’ll only forget the next time I need to do this. Sigh.

Just look at the filename of your profile picture. The uid is in the middle. 186939_565140267_839650_n.jpg Er... That's it. Bye.

Just look at the filename of your profile picture. The uid is in the middle.

186939_565140267_839650_n.jpg

Er… That’s it.

Bye.

When you use Chrome's omnibar to search, Chrome will redirect you to search results based on when you are geographically. This is great when I'm at home because I see (more relevant) results from google.co.uk and not google.com. However, I'm travelling at the moment and getting my results from google.co.th is painful since most of ...

When you use Chrome’s omnibar to search, Chrome will redirect you to search results based on when you are geographically. This is great when I’m at home because I see (more relevant) results from google.co.uk and not google.com.

However, I’m travelling at the moment and getting my results from google.co.th is painful since most of the results are not in english.

1. Close Chrome.
2. Open the file “Local State” in notepad. Mine was in: C:\Users\matt\AppData\Local\Google\Chrome\User Data\Local State. Linux users may find it in ~/.config/google-chrome/ or ~/.config/chromium/, and OS X users can try ~/Library/Application Support/Google/Chrome.
3. Look for “last_known_google_url” and “last_prompted_google_url” and change their values to the local Google page of your choice.
4. Save and close.
5. Done.

Thanks to Siavash for originally posting this.

At the end of April I set myself the challenge of gaining a stone in weight and running a 5km race 2.5 minutes faster. I ran the same race on Tuesday in 19:15, painfully close to my speed target of 19 minutes. However, I also weighed myself again but have actually lost a pound. Gah! Must try ...

At the end of April I set myself the challenge of gaining a stone in weight and running a 5km race 2.5 minutes faster.

I ran the same race on Tuesday in 19:15, painfully close to my speed target of 19 minutes. However, I also weighed myself again but have actually lost a pound.

Gah!

Must try harder…

Having trouble rotating something you've drawn with GWTCanvas? It took me a little while to work out, but GWTCanvas works slightly differently to Graphic2D in Java. It's important to realise that with GWTCanvas, when you invoke "rotate(r)" you're actually transforming the coordinate space that will be used for subsequent drawing. canvas.moveTo(50, 50); canvas.lineTo(50, 10); canvas.stroke(); Produces: In order to rotate ...

Having trouble rotating something you’ve drawn with GWTCanvas?

It took me a little while to work out, but GWTCanvas works slightly differently to Graphic2D in Java. It’s important to realise that with GWTCanvas, when you invoke “rotate(r)” you’re actually transforming the coordinate space that will be used for subsequent drawing.

canvas.moveTo(50, 50);
canvas.lineTo(50, 10);

canvas.stroke();

Produces:

In order to rotate it, you must invoke rotate before you start any drawing.
canvas.translate(50, 50);
canvas.rotate(Math.toRadians(45));
canvas.translate(-50, -50);

canvas.stroke();


Tadaa!

The same is also true for other transformation methods such as “scale” and “translate”.