Theo's Typesafe Cult•7mo ago

Multiple Generics In Typescript Type

Building a library that lets you pull in all of your analytics events and make Typesafe queries of them, running into a problem with multiple generics Events is a key, object pair which stores information about the events

type AnalyticsEvents = typeof events;

type AnalyticsEvent = AnalyticsEvents[keyof AnalyticsEvents];

type SamplingOptions = "TotalCount"

type Filter<T extends keyof AnalyticsEvents> = {
  name: AnalyticsEvents[T]["properties"][number]["name"];
  compare: "equals";
  value: string | number | boolean;
};

type SeriesEntry<T extends keyof AnalyticsEvents> = {
  name: T;
  sampling?: SamplingOptions;
  where?: Filter<T> | Filter<T>[];
};

type InsightOptions<T extends keyof AnalyticsEvents> = {
  events: SeriesEntry<T> | SeriesEntry<T>[];
  filters?: [];
  breakdownBy?: AnalyticsEvents[T]["properties"][number]["name"];
};

function fetchInsight<T extends keyof AnalyticsEvents>(
  options: InsightOptions<T>
) {}

type AnalyticsEvents = typeof events;

type AnalyticsEvent = AnalyticsEvents[keyof AnalyticsEvents];

type SamplingOptions = "TotalCount"

type Filter<T extends keyof AnalyticsEvents> = {
  name: AnalyticsEvents[T]["properties"][number]["name"];
  compare: "equals";
  value: string | number | boolean;
};

type SeriesEntry<T extends keyof AnalyticsEvents> = {
  name: T;
  sampling?: SamplingOptions;
  where?: Filter<T> | Filter<T>[];
};

type InsightOptions<T extends keyof AnalyticsEvents> = {
  events: SeriesEntry<T> | SeriesEntry<T>[];
  filters?: [];
  breakdownBy?: AnalyticsEvents[T]["properties"][number]["name"];
};

function fetchInsight<T extends keyof AnalyticsEvents>(
  options: InsightOptions<T>
) {}

Given above, the following should error in the second where since Answer Overflow Acount Id doesn't exist on autocapture, but since I can only do one generic it uses the combined type for both

fetchInsight({
  events: [
    {
      name: "User Grant Consent",
      sampling: "TotalCount",
      where: {
        name: "Answer Overflow Account Id",
        compare: "equals",
        value: 123,
      },
    },
    {
      name: "$autocapture",
      where: {
        name: "Answer Overflow Account Id",
        compare: "equals",
        value: 123,
      },
    },
  ],
});

fetchInsight({
  events: [
    {
      name: "User Grant Consent",
      sampling: "TotalCount",
      where: {
        name: "Answer Overflow Account Id",
        compare: "equals",
        value: 123,
      },
    },
    {
      name: "$autocapture",
      where: {
        name: "Answer Overflow Account Id",
        compare: "equals",
        value: 123,
      },
    },
  ],
});

7 Replies

Rhys•7mo ago

The problem is with

function fetchInsight<T extends keyof AnalyticsEvents>(
  options: InsightOptions<T>
) {}

function fetchInsight<T extends keyof AnalyticsEvents>(
  options: InsightOptions<T>
) {}

I can't think of a way to make it do the generic on a per event basis, maybe I could do something with a builder pattern? Source code also https://github.com/RhysSullivan/analytics-renderer

GitHub

GitHub - RhysSullivan/analytics-renderer

Contribute to RhysSullivan/analytics-renderer development by creating an account on GitHub.

Rhys•7mo ago

Here's the events array:

message.txt

Rhys•7mo ago

Maybe a syntax like would work?

Rhys•7mo ago

i realize now that this is literally just Drizzle for PostHog

Rhys•7mo ago

This works but the types are wrong

Rhys•7mo ago

function execute<T extends AnalyticsEventNames>(series: SeriesEntry<T>[]) {
  console.log("series", series);
  return [
    {
      hello: "world",
    },
  ];
}

function addSeries<
  Current extends AnalyticsEventNames,
  Existing extends AnalyticsEventNames,
  Next extends AnalyticsEventNames
>(
  series: SeriesEntry<Current>,
  existingSeries?: SeriesEntry<Existing> | SeriesEntry<Existing>[]
) {
  const existing = Array.isArray(existingSeries)
    ? existingSeries
    : existingSeries
    ? [existingSeries]
    : [];
  return {
    addSeries: (series: SeriesEntry<Next>) =>
      addSeries(series, [...existing, series]),
    execute: () => execute([...existing, series]),
  };
}

function execute<T extends AnalyticsEventNames>(series: SeriesEntry<T>[]) {
  console.log("series", series);
  return [
    {
      hello: "world",
    },
  ];
}

function addSeries<
  Current extends AnalyticsEventNames,
  Existing extends AnalyticsEventNames,
  Next extends AnalyticsEventNames
>(
  series: SeriesEntry<Current>,
  existingSeries?: SeriesEntry<Existing> | SeriesEntry<Existing>[]
) {
  const existing = Array.isArray(existingSeries)
    ? existingSeries
    : existingSeries
    ? [existingSeries]
    : [];
  return {
    addSeries: (series: SeriesEntry<Next>) =>
      addSeries(series, [...existing, series]),
    execute: () => execute([...existing, series]),
  };
}

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Multiple Generics In Typescript Type