Pretty Gotify notifications from ChangeDetection.io's Price-mode

changedetection_price_notifications.md

This is a very, very dirty way of turning ChangeDetection.io's price-mode output, which is JSON, into a more friendly markdown format. Using Jinja2, which is currently lacking a from_json function, we replace parts of the JSON output to form a markdown message. This will only work correctly as long as ChangeDetection.io's price-mode override JSON format stays EXACTLY the same. Any non HTTP 200 response might trigger such a change in which case a malformed message might be produced and send. Not something that could (should) "break" your ChangeDetection.io or notification service. Which is Gotify in this example gist. Tested with Tweakers.net Pricewatch product pages.

Example output

Some Product has changed!

• Lowest: 235.67 → 235.65
• Highest: 482.57
• Sellers: 33
• Currency: EUR

https://tracking-and-comparing-web.site/some-product.html

---

Known bugs

A malformed message will be send out when either lowPrice + highPrice, highPrice + offerCount or offerCount + priceCurrency changes at the same time. This is due to the implementation of jsdiff. A working solution for this problem has currently not yet been found.

---

Notification URL List

gotify://HOSTNAME/TOKEN?format=markdown&priority=moderate

Notification Title

Pricewatch update

Notification Body

**[{{watch_title}}]({{diff_url}})** has changed!
{{diff_full|replace("\n", "\n- ")|replace(",\n", "\n")|replace("{\n", "")|replace("\n- }", "")|replace("(changed) ", "")|replace("\n- (into) ", " -> ")|replace('-     "@type": "AggregateOffer"\n', '')|replace('    "lowPrice": ', 'Lowest: ')|replace('    "highPrice": ', 'Highest: ')|replace('    "offerCount": ', 'Sellers: ')|replace('    "priceCurrency": ', 'Currency: ')|replace(" -> Lowest: ", " -> ")|replace(" -> Highest: ", " -> ")|replace(" -> Sellers: ", " -> ")|replace(" -> Currency: ", " -> ")|replace(" -> ", " → ")|replace('"', '')|truncate(32768)}}

*[{{watch_url}}]({{watch_url}})*

Line 2 explanation:

{{

# Use the full differential result
diff_full

# Place list item after every newline (all except the first line)
|replace("\n", "\n- ")

# Remove all commas before newlines
|replace(",\n", "\n")

# Remove JSON opening tag (the first line)
|replace("{\n", "")

# Remove JSON closing tag
|replace("\n- }", "")

# Remove changed-prefix
|replace("(changed) ", "")

# Turn into-prefix, including the leading newline, into arrow
|replace("\n- (into) ", " -> ")

# Remove "@type" line
|replace('-     "@type": "AggregateOffer"\n', '')

# Change key names to friendly names
|replace('    "lowPrice": ',      'Lowest: '  )
|replace('    "highPrice": ',     'Highest: ' )
|replace('    "offerCount": ',    'Sellers: ' )
|replace('    "priceCurrency": ', 'Currency: ')

# Remove key names for changed values
|replace(" -> Lowest: ",   " -> ")
|replace(" -> Highest: ",  " -> ")
|replace(" -> Sellers: ",  " -> ")
|replace(" -> Currency: ", " -> ")

# Turn "->" into character
|replace(" -> ", " → ")

# Remove quotes
|replace('"', '')

# Truncate lenght
|truncate(32768)

}}

Notification format

Markdown