Contexts

From the example of the Quickstart, you might notice that in our template, we use a variable that has a default value. What if we want to change the value of the variable? Simple, we add a context to the template in the project.

Modify myfolio.py file to look like this:

from folio import Folio

proj = Folio(__name__)

@proj.context('hello.html')
def hello_context(jinja_env):
    return {'name': 'Pachi'}

if __name__ == "__main__":
    proj.build()

The new function hello_context() will be registered with the decorator folio.Folio.context() to add a new set of variables assigned to the template hello.html.

Re-build your project as before and in the build directory, the hello.html will say “Hello Pachi!” instead of “Hello World!”.

Add a context

The decorator is a shortcut to use the folio.Folio.add_context() method. The previous example could be written as:

def hello_context(jinja_env):
    return {'name': 'Pachi'}
proj.add_context('hello.html', hello_context)

Or without a callback function:

proj.add_context('hello.html', {'name': 'Pachi'})

The same context could be added to several templates, it’s as simple as passing a list to the first argument:

proj.add_context(['index.html', 'hello.html'], {'name': 'Pachi'})

In the same way, several contexts could be added to the same template. At the end they will merged into one dictionary in the same order as they were added. For example:

proj.add_context('index.html', {'name': 'Juan', 'files': [])
proj.add_context('index.html', lambda env: {'name': 'Flor'})

Will generate the context {'name': 'Flor', 'files': []}.

The templates names could be matched with a file name pattern. This is very useful, for example, to add a context to all the templates (that maybe is used in the layout template and not in each template per se):

@proj.context('*')
def add_nav(jinja_env):
    links = [('Home', 'index.html'),
             ('Downloads', 'download.html')]
    return {'nav': links}

The matching is done by the module fnmatch.