Collecting data with Trackers and Webhooks

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Tracking specific events

Snowplow has been built to enable you to track a wide range of events that occur when users interact with your websites and apps. We are constantly growing the range of functions available in order to capture that data more richly.

Tracking methods supported by the Ruby Tracker at a glance:

track_page_viewTrack and record views of web pages.
track_ecommerce_transactionTrack an ecommerce transaction
track_screen_viewTrack the user viewing a screen within the application
track_struct_eventTrack a Snowplow custom structured event
track_self_describing_eventTrack a Snowplow custom unstructured event


All events are tracked with specific methods on the tracker instance, of the form track_XXX(), where XXX is the name of the event to track.

All tracker methods return the tracker instance, and so are chainable.

Argument validation

Each track_XXX method expects arguments of a certain type. The types are validated using the Ruby Contracts library. If a check fails, a runtime error is thrown. The section for each track_XXX method specifies the expected argument types for that method.

Optional context argument

Each track_XXX method has context as its penultimate optional parameter. This is for an optional non-empty array of self-describing custom context JSONs attached to the event. Each element of the context argument should be a SelfDescribingJson with two fields: the “schema”, pointing to the JSON schema against which the context will be validated, and the “data”, containing the context data itself. The “data” field should contain a flat hash of key-value pairs.


  • Even if only one custom context is being attached to an event, it still needs to be wrapped in an array.

For example, an array containing two custom contexts relating to the event of a movie poster being viewed:

# Array of contexts [ # First context 'iglu:com.my_company/movie_poster/jsonschema/1-0-0', { 'movie_name' => 'Solaris', 'poster_country' => 'JP', 'poster_year$dt' => new Date(1978, 1, 1) } ), # Second context 'iglu:com.my_company/customer/jsonschema/1-0-0', { 'p_buy' => 0.23, 'segment' => 'young adult' } ) ]
Code language: PHP (php)

The keys of a context hash can be either strings or Ruby symbols.

For more on how to use custom contexts, see the blog post which introduced them.

Optional timestamp argument

After the optional context argument, each track_XXX method supports an optional timestamp as its final argument. This allows you to manually override the timestamp attached to this event. If you do not pass this timestamp in as an argument, then the Ruby Tracker will use the current time to be the timestamp for the event. Timestamp is counted in milliseconds since the Unix epoch – the same format generated by * 1000 in Ruby.

As of version 0.6.0, providing a SnowplowTracker::TrueTimestamp object as the timestamp argument will attach a true timestamp to the event, replacing the device timestamp. For example:

e ='com.acme') t = t.track_page_view('', 'Snowplow Ruby Tracker 0.6.0 released', '', nil,
Code language: PHP (php)

will send a page view event with a true timestamp to a collector at ‘com.acme’. An overridden device timestamp can be still be created in the following way:

e ='com.acme') t = t.track_page_view('', 'Snowplow Ruby Tracker 0.6.0 released', '', nil, 1471419787572)
Code language: PHP (php)


Here is an example of a page view event with custom context and timestamp arguments supplied:

tracker.track_page_view('', nil, nil, [ # First context 'iglu:com.my_company/movie_poster/jsonschema/1-0-0', { 'movie_name' => 'Solaris', 'poster_country' => 'JP', 'poster_year$dt' => new Date(1978, 1, 1) } ), # Second context 'iglu:com.my_company/customer/jsonschema/1-0-0', { 'p_buy' => 0.23, 'segment' => 'young adult' } ) ], 1368725287000)
Code language: PHP (php)

Track screen views with track_screen_view

Use track_screen_view() to track a user viewing a screen (or equivalent) within your app. Arguments are:

nameHuman-readable name for this screenYesString
idUnique identifier for this screenNoString
contextCustom contextNoArray[SelfDescribingJson]
tstampWhen the screen was viewedNoPositive integer


tracker.track_screen_view("HUD > Save Game", "screen23")
Code language: JavaScript (javascript)

Track page views with track_page_view

Use track_page_view() to track a user viewing a page within your app. Arguments are:

page_urlThe URL of the pageYesString
page_titleThe title of the pageNoString
referrerThe address which linked to the pageNoString
contextCustom contextNoArray[SelfDescribingJson]
tstampWhen the pageview occurredNoPositive integer


t.track_page_view("", "example", "")
Code language: CSS (css)

4.4 Track ecommerce transactions with track-ecommerce-transaction()

Use track_ecommerce_transaction() to track an ecommerce transaction. Arguments:

transactionData for the whole transactionYesHash
itemsData for each itemYesArray of hashes
contextCustom contextNoArray[SelfDescribingJson]
tstampWhen the transaction event occurredNoPositive integer

The transaction argument is a hash containing information about the transaction. Here are the fields supported in this hash:

order_idID of the eCommerce transactionYesString
total_valueTotal transaction valueYesInt or Float
affiliationTransaction affiliationNoString
tax_valueTransaction tax valueNoInt or Float
shippingDelivery cost chargedNoInt or Float
cityDelivery address cityNoString
stateDelivery address stateNoString
countryDelivery address countryNoString
currencyTransaction currencyNoString

The transaction parameter might look like this:

{ 'order_id' => '12345' 'total_value' => 35 'city' => 'London' 'country' => 'UK' 'currency' => 'GBP' }
Code language: PHP (php)

The items parameter is an array of hashes. Each hash represents one item in the transaction. Here are the fields supported for each item:

skuItem SKUYesString
priceItem priceYesInt or Float
quantityItem quantityYesInt
nameItem nameNoString
categoryItem categoryNoString
contextCustom contextNoArray[SelfDescribingJson]

The items parameter might look like that:

[{ 'sku' => 'pbz0026', 'price' => 20, 'quantity' => 1, 'category' => 'film' }, { 'sku' => 'pbz0038', 'price' => 15, 'quantity' => 1, 'name' => 'red shoes' }]
Code language: PHP (php)

The whole method call would look like this:

tracker.track_ecommerce_transaction({ 'order_id' => '12345' 'total_value' => 35 'city' => 'London' 'country' => 'UK' 'currency' => 'GBP' }, [{ 'sku' => 'pbz0026', 'price' => 20, 'quantity' => 1, 'category' => 'film' }, { 'sku' => 'pbz0038', 'price' => 15, 'quantity' => 1, 'name' => 'red shoes' }])
Code language: PHP (php)

This will fire three events: one for the transaction as a whole, which will include the fields in the transaction argument, and one for each item. The order_id and currency fields in the transaction argument will also be attached to each the items’ events.

All three events will have the same timestamp and same randomly generated Snowplow transaction ID.

Note that each item in the transaction can have its own custom context.

4.5 Track structured events with track_struct_event

Use track_struct_event() to track a custom event happening in your app which fits the Google Analytics-style structure of having up to five fields (with only the first two required):

categoryThe grouping of structured events which this action belongs toYesString
actionDefines the type of user interaction which this event involvesYesString
labelA string to provide additional dimensions to the event dataNoString
propertyA string describing the object or the action performed on itNoString
valueA value to provide numerical data about the eventNoInt or Float
contextCustom contextNoArray[SelfDescribingJson]
tstampWhen the structured event occurredNoPositive integer


tracker.track_struct_event("shop", "add-to-basket", nil, "pcs", 2)
Code language: JavaScript (javascript)

4.7 Track self describing events with track_self_describing_event

This method was previously called track_unstruct_event.

Use track_self_describing_event() to track a custom event which consists of a name and a self-describing set of properties. This is useful when:

  • You want to track event types which are proprietary/specific to your business (i.e. not already part of Snowplow), or
  • You want to track events which have unpredictable or frequently changing properties

The arguments are as follows:

event_jsonThe properties of the eventYesSelfDescribingJson
contextCustom contextNoArray[SelfDescribingJson]
tstampWhen the unstructured event occurredNoPositive integer


tracker.track_self_describing_event( "iglu:com.example_company/save_game/jsonschema/1-0-2", { "saveId" => "4321", "level" => 23, "difficultyLevel" => "HARD", "dlContent" => true } ))
Code language: PHP (php)

The event_json argument is SelfDescribingJson. It has two fields: “schema”, containing a pointer to the JSON schema for the event, and “data”, containing the event data itself. The data field must be flat: properties cannot be nested.

The keys of the event_json hash can be either strings or Ruby symbols.