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Merge pull request #61 from AnnMarieW/path-variables
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Handle Variables in the URL
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@AnnMarieW
AnnMarieW authored Jan 6, 2022
2 parents 4100d35 + 2905871 commit b8d0a3f
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9 changes: 7 additions & 2 deletions CHANGELOG.md
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@@ -1,11 +1,16 @@
# Overview
Unlike other Plotly projects, `dash-labs` does **not** adhere to semantic versioning. This project is intended to make it easier to discuss and iterate on new ideas before they are incorporated into Dash itself. As such, maintaining backward compatibility within the `dash-labs` package is explicitly a non-goal.

## unreleased

### Added
-[#61](https://github.com/plotly/dash-labs/pull/61). New feature for handling variables in the URL.

## 1.0.1

### Fixed
- [#59](https://github.com/plotly/dash-labs/pull/59) Fixed bug the prevented order prop from changing the order of the modules in dash.page_registry
- [#55](https://github.com/plotly/dash-labs/pull/59) Fixed bug that prevented multipage apps from working in windows: Fixed bug #52. Transitioned function away from the glob library to the os library to ensure functionality with windows. See pull request #55.
- [#59](https://github.com/plotly/dash-labs/pull/59) Fixed bug that prevented order prop from changing the order of the modules in dash.page_registry
- [#55](https://github.com/plotly/dash-labs/pull/55) Fixed bug that prevented multipage apps from working in windows: Fixed bug #52. Transitioned function away from the glob library to the os library to ensure functionality with windows.

## 1.0.0

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220 changes: 161 additions & 59 deletions dash_labs/plugins/pages.py
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Original file line number Diff line number Diff line change
Expand Up @@ -9,22 +9,35 @@
from os.path import isfile, join
from textwrap import dedent
from urllib.parse import parse_qs
from keyword import iskeyword
import warnings

if not os.path.exists("pages"):
raise Exception("A folder called `pages` does not exist.")

def warning_message(message, category, filename, lineno, line=None):
return f"{category.__name__}:\n {message} \n"


warnings.formatwarning = warning_message

_ID_CONTENT = "_pages_plugin_content"
_ID_LOCATION = "_pages_plugin_location"
_ID_STORE = "_pages_plugin_store"
_ID_DUMMY = "_pages_plugin_dummy"

page_container = html.Div(
[dcc.Location(id=_ID_LOCATION), html.Div(id=_ID_CONTENT), html.Div(id=_ID_DUMMY)]
[
dcc.Location(id=_ID_LOCATION),
html.Div(id=_ID_CONTENT),
dcc.Store(id=_ID_STORE),
html.Div(id=_ID_DUMMY),
]
)


def register_page(
module,
path=None,
path_template=None,
name=None,
order=None,
title=None,
Expand All @@ -51,8 +64,15 @@ def register_page(
- `path`:
URL Path, e.g. `/` or `/home-page`.
If not supplied, will be inferred from `module`,
e.g. `pages.weekly_analytics` to `/weekly-analytics`
If not supplied, will be inferred from the `path_template` or `module`,
e.g. based on path_template: `/asset/<asset_id` to `/asset/none`
e.g. based on module: `pages.weekly_analytics` to `/weekly-analytics`
- path_template:
Add variables to a URL by marking sections with <variable_name>. The layout function
then receives the <variable_name> as a keyword argument.
e.g. path_template= "/asset/<asset_id>"
if pathname = "/assets/a100" then layout will receive {"asset_id":"a100"}
- `name`:
The name of the link.
Expand Down Expand Up @@ -124,7 +144,6 @@ def register_page(
description='Our historical view',
supplied_order=None,
order=1,
supplied_layout=None,
layout=<function pages.historical_outlook.layout>,
Expand All @@ -142,7 +161,10 @@ def register_page(
page = dict(
module=module,
supplied_path=path,
path=(path if path is not None else _filename_to_path(module)),
path_template=None
if path_template is None
else _validate_template(path_template),
path=(path if path is not None else _infer_path(module, path_template)),
supplied_name=name,
name=(name if name is not None else _filename_to_name(module)),
)
Expand Down Expand Up @@ -171,10 +193,14 @@ def register_page(
dash.page_registry[module]["layout"] = layout

# set home page order
order_supplied = any(p["supplied_order"] is not None for p in dash.page_registry.values())
order_supplied = any(
p["supplied_order"] is not None for p in dash.page_registry.values()
)

for p in dash.page_registry.values():
p["order"] = 0 if p["path"] == "/" and not order_supplied else p["supplied_order"]
p["order"] = (
0 if p["path"] == "/" and not order_supplied else p["supplied_order"]
)

# sorted by order then by module name
page_registry_list = sorted(
Expand All @@ -184,6 +210,7 @@ def register_page(

dash.page_registry = OrderedDict([(p["module"], p) for p in page_registry_list])


dash.register_page = register_page


Expand All @@ -194,7 +221,6 @@ def _infer_image(module):
- A generic app image at `assets/app.<extension>`
- A logo at `assets/logo.<extension>`
"""
# TODO - Make sure we don't need to use __name__?
page_id = module.split(".")[-1]
files_in_assets = []
if os.path.exists("assets"):
Expand Down Expand Up @@ -224,16 +250,38 @@ def _filename_to_name(filename):
return filename.split(".")[-1].replace("_", " ").capitalize()


def _filename_to_path(filename):
return filename.replace("_", "-").replace(".", "/").lower().split("pages")[-1]
def _validate_template(template):
template_segments = template.split("/")
for s in template_segments:
if "<" in s or ">" in s:
if not (s.startswith("<") and s.endswith(">")):
raise Exception(
f'Invalid `path_template`: "{template}" Path segments with variables must be formatted as <variable_name>'
)
variable_name = s[1:-1]
if not variable_name.isidentifier() or iskeyword(variable_name):
warnings.warn(
f'`{variable_name}` is not a valid Python variable name in `path_template`: "{template}".',
stacklevel=2,
)
return template


def plug(app):
# Import the pages so that the user doesn't have to.
# TODO - Do validate_layout in here too
dash.page_registry = OrderedDict()
def _infer_path(filename, template):
if template is None:
path = filename.replace("_", "-").replace(".", "/").lower().split("pages")[-1]
path = "/" + path if not path.startswith("/") else path
return path
else:
# replace the variables in the template with "none" to create a default path if no path is supplied
path_segments = template.split("/")
default_template_path = [
"none" if s.startswith("<") else s for s in path_segments
]
return "/".join(default_template_path)


# Updated from using glob.iglob to using os.walk to ensure that the function works for Windows users
def _import_layouts_from_pages():
for (root, dirs, files) in os.walk("pages"):
for file in files:
if file.startswith("_") or not file.endswith(".py"):
Expand All @@ -248,70 +296,105 @@ def plug(app):
page_module, "layout"
)


def _path_to_page(app, pathname):
path_id = app.strip_relative_path(pathname)
path_variables = None

for page in dash.page_registry.values():
if page["path_template"]:
template_id = app.strip_relative_path(page["path_template"])
path_variables = _parse_path_variables(path_id, template_id)
if path_variables:
return page, path_variables
if path_id == app.strip_relative_path(page["path"]):
return page, path_variables
return {}, None


def plug(app):
dash.page_registry = OrderedDict()

if os.path.exists("pages"):
_import_layouts_from_pages()
else:
warnings.warn("A folder called `pages` does not exist.", stacklevel=2)

@app.server.before_first_request
def router():
@callback(
Output(_ID_CONTENT, "children"),
Output(_ID_STORE, "data"),
Input(_ID_LOCATION, "pathname"),
Input(_ID_LOCATION, "search"),
prevent_initial_call=True,
)
def update(pathname, search):
path_id = app.strip_relative_path(pathname)
# updates layout on page navigation
# updates the stored page title which will trigger the clientside callback to update the app title

query_parameters = _parse_query_string(search)
layout = None
for module in dash.page_registry:
page = dash.page_registry[module]
if path_id == app.strip_relative_path(page["path"]):
layout = page["layout"]
page, path_variables = _path_to_page(app, pathname)

if layout is None:
# get layout
if page == {}:
if "pages.not_found_404" in dash.page_registry:
layout = dash.page_registry["pages.not_found_404"]["layout"]
title = {
"title": dash.page_registry["pages.not_found_404"]["title"]
}
else:
layout = html.H1("404")
title = {"title": app.title}
else:
layout = page["layout"]
title = {"title": page["title"]}

if callable(layout):
print("Calling...")
print(query_parameters)
return layout(**query_parameters)
else:
return layout
layout = (
layout(**path_variables, **query_parameters)
if path_variables
else layout(**query_parameters)
)

# Set validation_layout and prefix component IDs and callbacks with module name
for module in dash.page_registry:
app.validation_layout = html.Div(
[
page["layout"]() if callable(page["layout"]) else page["layout"]
for page in dash.page_registry.values()
]
+ [app.layout]
)
return layout, title

# Update the page title on page navigation
path_to_title = {
page["path"]: page["title"] for page in dash.page_registry.values()
}
path_to_description = {
page["path"]: page["description"] for page in dash.page_registry.values()
}
path_to_image = {
page["path"]: page["image"] for page in dash.page_registry.values()
}
# check for duplicate pathnames
path_to_module = {}
for page in dash.page_registry.values():
if page["path"] not in path_to_module:
path_to_module[page["path"]] = [page["module"]]
else:
path_to_module[page["path"]].append(page["module"])

for modules in path_to_module.values():
if len(modules) > 1:
raise Exception(f"modules {modules} have duplicate paths")

# Set validation_layout
app.validation_layout = html.Div(
[
page["layout"]() if callable(page["layout"]) else page["layout"]
for page in dash.page_registry.values()
]
+ [app.layout]
)

# Update the page title on page navigation
app.clientside_callback(
f"""
function(path) {{
document.title = {json.dumps(path_to_title)}[path] || 'Dash'
function(data) {{
document.title = data.title || 'Dash'
}}
""",
Output(_ID_DUMMY, "children"),
Input(_ID_LOCATION, "pathname"),
Input(_ID_STORE, "data"),
)

# Set index HTML for the meta description and page title on page load
def interpolate_index(**kwargs):
image = path_to_image.get(flask.request.path, "")
start_page, _ = _path_to_page(app, flask.request.path)
image = start_page.get("image", "")
if image:
image = app.get_asset_url(image)

Expand All @@ -322,20 +405,17 @@ def interpolate_index(**kwargs):
<head>
<title>{title}</title>
<meta name="description" content="{description}" />
<!-- Twitter Card data -->
<meta property="twitter:card" content="{description}">
<meta property="twitter:url" content="https://metatags.io/">
<meta property="twitter:title" content="{title}">
<meta property="twitter:description" content="{description}">
<meta property="twitter:image" content="{image}">
<!-- Open Graph data -->
<meta property="og:title" content="{title}" />
<meta property="og:type" content="website" />
<meta property="og:description" content="{description}" />
<meta property="og:image" content="{image}">
{metas}
{favicon}
{css}
Expand All @@ -352,8 +432,8 @@ def interpolate_index(**kwargs):
"""
).format(
metas=kwargs["metas"],
description=path_to_description.get(flask.request.path, ""),
title=path_to_title.get(flask.request.path, "Dash"),
description=start_page.get("description", ""),
title=start_page.get("title", app.title),
image=image,
favicon=kwargs["favicon"],
css=kwargs["css"],
Expand All @@ -376,9 +456,9 @@ def redirect():
page = dash.page_registry[module]
if page["redirect_from"] and len(page["redirect_from"]):
for redirect in page["redirect_from"]:
# TODO - Use pathname prefix
fullname = app.get_relative_path(redirect)
app.server.add_url_rule(
redirect, redirect, create_redirect_function(page["path"])
fullname, fullname, create_redirect_function(page["path"])
)


Expand All @@ -398,3 +478,25 @@ def _parse_query_string(search):

parsed_qs[k] = first
return parsed_qs


def _parse_path_variables(pathname, path_template):
"""
creates the dict of path variables passed to the layout
e.g. path_template= "/asset/<asset_id>"
pathname = "/assets/a100"
returns {"asset_id":"a100"}
"""
path_segments = pathname.split("/")
template_segments = path_template.split("/")

if len(path_segments) != len(template_segments):
return None

path_vars = {}
for path_segment, template_segment in zip(path_segments, template_segments):
if template_segment.startswith("<"):
path_vars[template_segment[1:-1]] = path_segment
elif template_segment != path_segment:
return None
return path_vars
3 changes: 0 additions & 3 deletions docs/demos/multi_page_basics/app.py
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Expand Up @@ -13,9 +13,6 @@
app.layout = html.Div(
[
html.H1("App Frame"),
html.Div(
dcc.Link("Go back home", href=dash.page_registry["pages.home"]["path"])
),
html.Div(
[
html.Div(
Expand Down
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