View Source Trifle.Stats.Formatter.Behaviour behaviour (Trifle.Stats v2.5.0)
Behaviour for custom formatter implementations.
Formatters transform time-series data into different presentation formats. They reshape data for visualization, reporting, or further processing.
Example Implementation
defmodule MyCustomFormatter do
@behaviour Trifle.Stats.Formatter.Behaviour
@impl true
def format(series, path, slices \ 1, transform_fn \ nil) do
# Extract values at the specified path
values = series[:values] || []
timeline = series[:at] || []
# Perform custom formatting logic
formatted_data = values
|> Enum.with_index()
|> Enum.map(fn {value, idx} ->
raw_value = get_in(value, String.split(path, "."))
transformed = if transform_fn, do: transform_fn.(raw_value), else: raw_value
%{
timestamp: Enum.at(timeline, idx),
value: transformed,
custom_field: "processed"
}
end)
%{format: "custom", data: formatted_data}
end
endSummary
Callbacks
Format data from a series at the specified path (2-arity version).
Format data from a series at the specified path (3-arity version).
Format data from a series at the specified path.
Callbacks
Format data from a series at the specified path (2-arity version).
Format data from a series at the specified path (3-arity version).
@callback format( series :: map(), path :: String.t(), slices :: integer(), transform_fn :: function() | nil ) :: map()
Format data from a series at the specified path.
Parameters
series: Map containing:at(timeline) and:values(data points) keyspath: String path to the values to format (e.g., "count", "metrics.duration")slices: Number of slices for windowed formatting (optional, defaults to 1)transform_fn: Optional transformation function to apply to each value
Returns
Formatted data structure. The exact format depends on the formatter implementation, but typically returns a map with structured presentation data.
Example
series = %{
at: [~U[2025-08-18 10:00:00Z], ~U[2025-08-18 11:00:00Z]],
values: [%{"count" => 10}, %{"count" => 15}]
}
format(series, "count", 1)
# => %{labels: ["count"], data: [[10, 15]]} # timeline format
format(series, "count", 1, &(&1 * 2))
# => %{labels: ["count"], data: [[20, 30]]} # with transform