70 lines
2.0 KiB
Markdown
70 lines
2.0 KiB
Markdown
title: Pad
|
|
---
|
|
summary: The basic interface to querying the database.
|
|
---
|
|
module: lektor.db
|
|
---
|
|
type: class
|
|
---
|
|
template_var: site
|
|
---
|
|
body:
|
|
|
|
The `Pad` is a helper class that provides basic access to querying the
|
|
database. Inside templates an instance of it is available under the
|
|
`site` variable automatically.
|
|
|
|
To understand what the pad does you need to consider what it is. The
|
|
pad is similar to a `connection` in a regular database. Whenever you
|
|
load a record it's temporarily cached on the pad. So unless you overflow
|
|
the cache, loading the object a second time will most likely return an
|
|
already loaded instance from the pad. This also means that the pad
|
|
is not threadsafe. So if you want (for whatever reason) use multiple
|
|
threads you have to create a separate pad for each thread.
|
|
|
|
This typically only comes up in the context of plugins or more complex
|
|
command line scripts.
|
|
|
|
## Template Usage
|
|
|
|
A ready-configured pad is always available under the `site` name which
|
|
allows you to easily discover other pages. Here is a basic example of
|
|
how to do this through the [get :ref](get/) method:
|
|
|
|
```html+jinja
|
|
{% set root = site.get('/') %}
|
|
<title>{{ this.title }} | {{ root.title }}</title>
|
|
```
|
|
|
|
## Plugin Usage
|
|
|
|
Within plugins it's typically not a good idea to construct a new Pad.
|
|
Instead you can get access to the current pad from the active context:
|
|
|
|
```python
|
|
from lektor.context import get_ctx
|
|
|
|
ctx = get_ctx()
|
|
if ctx is not None:
|
|
pad = get_ctx().pad
|
|
```
|
|
|
|
Note that you can only get access to a pad if a context is available. This
|
|
will not be the case when the plugin is currently being initialized for
|
|
instance.
|
|
|
|
## Manual Pad Creation
|
|
|
|
If you want to work with the database from a script, you can create a
|
|
pad from the [Environment :ref](../../environment/) with the help of
|
|
the [new_pad :ref](../../environment/new-pad/) method:
|
|
|
|
```python
|
|
from lektor.project import Project
|
|
|
|
project = Project.discover()
|
|
env = project.make_env()
|
|
pad = env.new_pad()
|
|
root_record = pad.root
|
|
```
|