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https://github.com/jiftechnify/nostr-fetch

A utility library that allows JS/TS apps to effortlessly fetch past events from Nostr relays.
https://github.com/jiftechnify/nostr-fetch

javascript nostr typescript

Last synced: about 2 months ago
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A utility library that allows JS/TS apps to effortlessly fetch past events from Nostr relays.

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README 

        
# nostr-fetch

A utility library that allows JS/TS apps to effortlessly fetch *past* events from Nostr relays.



## Installation



### for npm Project



```

npm install nostr-fetch

```



### for Deno Project



```

deno add npm:nostr-fetch

```



### for Browser Apps, without Bundlers

You can also use nostr-fetch in your HTML via `` tags, thanks to [jsDelivr](https://www.jsdelivr.com/).



```html

<script type="module">

  import { NostrFetcher } from "https://cdn.jsdelivr.net/npm/[email protected]/+esm"

  // ...



```



### Note for Users on Node.js < v22

Node.js < v22 doesn't have native WebSocket implementation. 

On Such a environment you may want to pass a custom `WebSocket` constructor from an external package like [`ws`](https://github.com/websockets/ws/tree/master) to `NostrFetcher.init()` as an option.



```

npm install ws

```



```ts

import { NostrFetcher } from "nostr-fetch";

import WebSocket from "ws";



const fetcher = NostrFetcher.init({ webSocketConstructor: WebSocket });

```



## Usage



### Basics



```ts

import { NostrFetcher } from "nostr-fetch";



const nHoursAgo = (hrs: number): number =>

  Math.floor((Date.now() - hrs * 60 * 60 * 1000) / 1000);



const fetcher = NostrFetcher.init();

const relayUrls = [/* relay URLs */];



// fetches all text events since 24 hr ago in streaming manner

const postIter = fetcher.allEventsIterator(

    relayUrls, 

    /* filter (kinds, authors, ids, tags) */

    { kinds: [ 1 ] },

    /* time range filter (since, until) */

    { since: nHoursAgo(24) },

    /* fetch options (optional) */

    { skipFilterMatching: true }

);

for await (const ev of postIter) {

    console.log(ev.content);

}



// fetches all text events since 24 hr ago, as a single array

const allPosts = await fetcher.fetchAllEvents(

    relayUrls,

    /* filter */

    { kinds: [ 1 ] },

    /* time range filter */

    { since: nHoursAgo(24) },

    /* fetch options (optional) */

    { sort: true }

)

```



### Various Fetch Methods



```ts

import { NostrFetcher } from "nostr-fetch";



const fetcher = NostrFetcher.init();

const relayUrls = [/* relay URLs */];



// fetches latest 100 text posts

// internally: 

// 1. fetch latest 100 events from each relay

// 2. merge lists of events

// 3. take latest 100 events

const latestPosts: NostrEvent[] = await fetcher.fetchLatestEvents(

    relayUrls,

    /* filter */

    { kinds: [ 1 ] },

    /* number of events to fetch */

    100,

);



// fetches the last metadata event published by pubkey "deadbeef..."

// internally:

// 1. fetch the last event from each relay

// 2. take the latest one

const lastMetadata: NostrEvent | undefined = await fetcher.fetchLastEvent(

    relayUrls,

    /* filter */

    { kinds: [ 0 ], authors: [ "deadbeef..." ] },

);



// fetches latest 10 text posts from each author in `authors`

const postsPerAuthor = fetcher.fetchLatestEventsPerAuthor(

    /* authors and relay set */

    // you can also pass a `Map` which has mappings from authors (pubkey) to reley sets,

    // to specify a relay set for each author

    { 

        authors: ["deadbeef...", "abcdef01...", ...],

        relayUrls,

    },

    /* filter */

    { kinds: [ 1 ] },

    /* number of events to fetch for each author */

    10,

);

for await (const { author, events } of postsPerAuthor) {

    console.log(`posts from ${author}:`);

    for (const ev of events) {

        console.log(ev.content);

    }

}



// fetches the last metadata event from each author in `authors`

const metadataPerAuthor = fetcher.fetchLastEventPerAuthor(

    /* authors and relay set */

    // you can also pass a `Map` which has mappings from authors (pubkey) to reley sets,

    // to specify a relay set for each author

    {

        authors: ["deadbeef...", "abcdef01...", ...],

        relayUrls,

    }

    /* filter */

    { kinds: [ 0 ] },

);

for await (const { author, event } of metadataPerAuthor ) {

    console.log(`${author}: ${event?.content ?? "not found"}`);

}

```



### Working with custom relay pool implementations



First, install the adapter package for the relay pool implementation you want to use.

For example, if you want to use nostr-fetch with nostr-tools' `SimplePool` :



```bash

npm install @nostr-fetch/adapter-nostr-tools

```



Then, wrap your relay pool instance with the adapter and pass it to the initializer `NostrFetcher.withCustomPool()`.

```ts

import { NostrFetcher } from "nostr-fetch";

import { simplePoolAdapter } from "@nostr-fetch/adapter-nostr-tools";

import { SimplePool } from "nostr-tools";



const pool = new SimplePool();



// wrap SimplePool with simplePoolAdapter to make it interoperable with nostr-fetch

const fetcher = NostrFetcher.withCustomPool(simplePoolAdapter(pool));



// now, you can use any fetch methods described above!

```



#### Table of Available Adapters



| Package                                                               | Relay Pool Impl. | Adapter Package                        | Adapter             |

|-----------------------------------------------------------------------|------------------|----------------------------------------|---------------------|

| [`nostr-tools`](https://github.com/nbd-wtf/nostr-tools) (v1)          | `SimplePool`     | `@nostr-fetch/adapter-nostr-tools`     | `simplePoolAdapter` |

| [`nostr-tools`](https://github.com/nbd-wtf/nostr-tools) (v2)          | `SimplePool`     | `@nostr-fetch/adapter-nostr-tools-v2`  | `simplePoolAdapter` |

| [`nostr-relaypool`](https://github.com/adamritter/nostr-relaypool-ts) | `RelayPool`      | `@nostr-fetch/adapter-nostr-relaypool` | `relayPoolAdapter`  |

| [`@nostr-dev-kit/ndk`](https://github.com/nostr-dev-kit/ndk)          | `NDK`            | `@nostr-fetch/adapter-ndk`             | `ndkAdapter`        |

| [`rx-nostr`](https://github.com/penpenpng/rx-nostr) (v1)              | `RxNostr`        | `@nostr-fetch/adapter-rx-nostr`        | `rxNostrAdapter`    |



### Cancelling by AbortSignal



```ts

import { NostrFecher } from "nostr-fetch"



const fetcher = NostrFetcher.init();

const relayUrls = [/* relay URLs */];



const evIter = fetcher.allEventsIterator(

    relayUrls,

    {/* filter */},

    {/* time range */},

    /* pass an `AbortSignal` here to enable cancellation! */

    { signal: AbortSignal.timeout(1000) },

);



for await (const ev of evIter) {

    // ...

}

```



## Examples

You can find example codes under `packages/examples` directory.



To run examples, follow the steps (using `npm` for example):



```bash

# first time only: install dependencies & build subpackages

npm install && npm run build



# then, execute example

# the command executes packages/examples/src/fetchAll.ts

npm run example fetchAll



# some examples takes a hex pubkey as an argument

npm run example fetchLastPerAuthor 

```



## API



- [class `NostrFetcher`](#class-nostrfetcher)

- Initializers and Finilizers

    + [`NostrFetcher.init`](#nostrfetcherinit)

    + [`NostrFetcher.withCustomPool`](#nostrfetcherwithcustompool)

    + [`NostrFetcher#shutdown`](#nostrfetchershutdown)

- Fetch Methods

    + [`allEventsIterator`](#alleventsiterator)

    + [`fetchAllEvents`](#fetchallevents)

    + [`fetchLatestEvents`](#fetchlatestevents)

    + [`fetchLastEvent`](#fetchlastevent)

    + [`fetchLatestEventsPerKey`](#fetchlatesteventsperkey)

    + [`fetchLastEventPerKey`](#fetchlasteventperkey)

    + [`fetchLatestEventsPerAuthor`](#fetchlatesteventsperauthor)

    + [`fetchLastEventPerAuthor`](#fetchlasteventperauthor)



### class `NostrFetcher`



The entry point of Nostr events fetching. 



It manages connections to Nostr relays under the hood. It is recommended to reuse single `NostrFetcher` instance in entire app.



You should instantiate it with following initializers instead of the constructor.



---



### Initializers and Finalizers



#### `NostrFetcher.init`



Initializes a `NostrFetcher` instance based on the default relay pool implementation.



#### `NostrFetcher.withCustomPool`



Initializes a `NostrFetcher` instance based on a custom relay pool implementation passed as an argument.



This opens up interoperability with other relay pool implementations such as [nostr-tools](https://github.com/nbd-wtf/nostr-tools)' `SimplePool`.  See [here](#working-with-custom-relay-pool-implementations) for details.



#### `NostrFetcher#shutdown`



Cleans up the internal relay pool.



If you use a fetcher instance initialized via `NostrFetcher.init`, calling this method closes connections to all the connected relays.



You can use [a variable with `using` keyword](https://www.typescriptlang.org/docs/handbook/release-notes/typescript-5-2.html#using-declarations-and-explicit-resource-management) to automatically shutdown a fetcher instance when the scope of the `using` variable ends. Roughly speaking, `withFinally()` and `withUsing()` in the code bellow are the same.



```ts

async function withFinally() {

    const fetcher = NostrFetcher.init();

    try {

        // do some work with the fetcher...

    } finally {

        fetcher.shutdown();

    }

}



async function withUsing() {

    using fetcher = NostrFetcher.init();

    // do some work with the fetcher...



    // the fetcher will be automatically shutdown here!

}

```



---



### Fetch Methods



All methods are instance methods of `NostrFetcher`.



#### `allEventsIterator`



```ts

public allEventsIterator(

    relayUrls: string[],

    filter: FetchFilter,

    timeRangeFilter: FetchTimeRangeFilter,

    options?: AllEventsIterOptions

): AsyncIterable

```



Returns an async iterable of all events matching the filter from Nostr relays specified by the array of URLs.



You can iterate over events using for-await-of loop.



```ts

const fetcher = NostrFetcher.init();

const events = fetcher.allEventsIterator([/* relays */], {/* filter */}, {/* time range */});

for await (const ev of events) {

    // process events

}

```



Specifying `enableBackpressure: true` in `options` enables "backpressure mode", where the fetcher is backpressured by the consumer of the iterator.



> **Note**

>

> There are no guarantees about the order of returned events. Especially, events are not necessarily ordered in "newest to oldest" order.



---



#### `fetchAllEvents`



```ts

public async fetchAllEvents(

    relayUrls: string[],

    filter: FetchFilter,

    timeRangeFilter: FetchTimeRangeFilter,

    options?: FetchAllOptions

): Promise

```



Fetches all events matching the filter from Nostr relays specified by the array of URLs, and collect them into an array.



If `sort: true` is specified in `options`, events in the resulting array will be sorted in "newest to oldest" order.



> **Note**

>

> There are no guarantees about the order of returned events if `sort` options is not specified.



---



#### `fetchLatestEvents`



```ts

public async fetchLatestEvents(

    relayUrls: string[],

    filter: FetchFilter,

    limit: number,

    options?: FetchLatestOptions

): Promise

```



Fetches latest up to `limit` events matching the filter from Nostr relays specified by the array of URLs. 



Events in the result will be sorted in "newest to oldest" order.



---



#### `fetchLastEvent`



```ts

public async fetchLastEvent(

    relayUrls: string[],

    filter: FetchFilter,

    options?: FetchLatestOptions

): Promise

```



Fetches the last event matching the filter from Nostr relays specified by the array of URLs.



Returns `undefined` if no event matching the filter exists in any relay.



---



#### `fetchLatestEventsPerKey`



```ts

public fetchLatestEventsPerKey(

    keyName: KN,

    keysAndRelays: KeysAndRelays,

    otherFilter: FetchFilter,

    limit: number,

    options?: FetchLatestOptions

): AsyncIterable>

```



Fetches latest up to `limit` events **for each key specified by `keyName` and `keysAndRelays`**.



`keysAndRelays` can be either of two types:



- `{ keys: K[], relayUrls: string[] }`: The fetcher will use the same relay set (`relayUrls`) for all `keys` to fetch events.

- `Map`: Key must be the key of event and value must be relay set for that key. The fetcher will use separate relay set for each key to fetch events.



> **Note**

>

> The type `K` is `number` if `keyName` is `"kinds"`. Otherwise, `K` is `string`.



Result is an async iterable of `{ key: , events:  }` pairs.



Each array of events in the result are sorted in "newest to oldest" order.



---



#### `fetchLastEventPerKey`



```ts

public fetchLatestEventsPerKey(

    keyName: KN,

    keysAndRelays: KeysAndRelays,

    otherFilter: FetchFilter,

    options?: FetchLatestOptions

): AsyncIterable>

```



Fetches the last event **for each key specified by `keysAndRelays`**.



`keysAndRelays` can be either of two types:



- `{ keys: K[], relayUrls: string[] }`: The fetcher will use the same relay set (`relayUrls`) for all `keys` to fetch events.

- `Map`: Key must be key of the event and value must be relay set for that key. The fetcher will use separate relay set for each key to fetch events.



> **Note**

>

> The type `K` is `number` if `keyName` is `"kinds"`. Otherwise, `K` is `string`.



Result is an async iterable of `{ key: , event:  }` pairs.



`event` in result will be `undefined` if no event matching the filter exists in any relay.



---



#### `fetchLatestEventsPerAuthor`



```ts

public fetchLatestEventsPerAuthor(

    authorsAndRelays: AuthorsAndRelays,

    otherFilter: Omit,

    limit: number,

    options: FetchLatestOptions = {}

): AsyncIterable<{ author: string; events: NostrEvent[] }>

```

Fetches latest up to `limit` events **for each author specified by `authorsAndRelays`**.



It is just a wrapper of `fetchLatestEventsPerKey` specialized to `"authors"` key.



---



#### `fetchLastEventPerAuthor`



```ts

public fetchLastEventPerAuthor(

    authorsAndRelays: AuthorsAndRelays,

    otherFilter: Omit,

    options: FetchLatestOptions = {}

): AsyncIterable<{ author: string; event: NostrEvent | undefined }>

```



Fetches the last event **for each author specified by `authorsAndRelays`**.



It is just a wrapper of `fetchLastEventPerKey` specialized to `"authors"` key.



## Support me!

You can support this project by:



- ⭐ Starring the repo

- ⚡️ Sending some sats to my lightning address: [email protected]

- 🐝 Sending funds via [PkgZap](https://pkgzap.albylabs.com/)