Posts Tagged ‘python’

Unicode in Mako using Pylons

Small post regarding unicode support in mako. I learned yesterday that mako not only has input and output encoding options but also an default_filter encoding. In the file, in your Pylons config folder, you need all these three to be sure that everything is enoded as unicode. Remember though that the default_filters argument can have big impact on performance.

(If someone knows the configuration files for other frameworks, please write a comment about it and I’ll add it to the post)

Please read the Mako unicode chapter here if you want the gory details.
 config['pylons.app_globals'].mako_lookup = TemplateLookup(
        default_filters=['decode.utf8'] )

Serving images directly from database

Even though storing images in the database have its advantages/disadvantages, here is a small guide for those who want to store them in the database and serve them directly to the browser without having to generate a file first. This examples is based on the amazing web framework pylons.

In this example I want to serve small product images from my product controller.

In the controller I have this method

def show_image(self, id, name):
    response.headers['Content-type'] = 'image/png'
    response.headers['Cache-Control'] = 'max-age=14400'
    response.headers['Pragma'] = ''
    product = Product.get_by(id=id)
    return product.image

Then in my mako template I have

<img src="url(controller='product', action='show_image', id='${}', name='c.product.image_name')"/>

which will generate

<img src="/product/show_image/1/super-glue.png"/>

So whats happening is that when the page is loading the image tag, the show_image() function is called which fetches the image data from the database and returns the image data buffer to the template. The key for this to work is to set the appropriate headers so that the page know that the data returned is image/png through the Content-type. The name argument is just used to set a name for the image file on the connecting client so that the cached file will have a correct name.