https://github.com/keredson/pouchdb-expo-fix
Fixes so PouchDB will run under Expo / React Native
https://github.com/keredson/pouchdb-expo-fix
Last synced: 2 months ago
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Fixes so PouchDB will run under Expo / React Native
- Host: GitHub
- URL: https://github.com/keredson/pouchdb-expo-fix
- Owner: keredson
- License: mit
- Created: 2021-05-31T16:30:19.000Z (about 5 years ago)
- Default Branch: main
- Last Pushed: 2021-06-03T00:37:00.000Z (about 5 years ago)
- Last Synced: 2025-01-28T05:41:37.283Z (over 1 year ago)
- Language: JavaScript
- Size: 124 KB
- Stars: 1
- Watchers: 3
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# PouchDB Expo Fix
## About
[PouchdB](https://pouchdb.com/) is a database I recently started exploring. But it sadly
doesn't work inside Expo, or worse, fails silently (or with untracable promise errors)
when a document with an attachment is synced. This package is a collection of hacks I
implemented / pulled from other resources to make it usable.
## Installation
### Dependencies
In your expo app you will need these dependencies:
```bash
$ yarn add pouchdb-core pouchdb-adapter-http pouchdb-replication \
pouchdb-adapter-utils pouchdb-adapter-websql-core events \
expo-sqlite expo-crypto react-native-get-random-values
```
And of course:
```bash
$ yarn add pouchdb-expo-fix
```
### Code Changes
Enable the fixes to PouchDB with the following code:
```javascript
import PouchDB from 'pouchdb-core';
import PouchDBExpoFix from 'pouchdb-expo-fix';
require('pouchdb-adapter-utils').preprocessAttachments = PouchDBExpoFix.fix_pouchdb_adapter_utils()
PouchDB.plugin(PouchDBExpoFix.build_sqlite_adapter(require('pouchdb-adapter-websql-core')))
```
That should be it, but look out for the possible errors listed below (esp. `FileReader.readAsArrayBuffer`).
## Possible Errors
### Random Values Error
This project will do the following import for you:
```javascript
import 'react-native-get-random-values'
```
But this import must be called **before** `uuid` is imported elsewhere in your app. If you get:
```javascript
Unhandled promise rejection: Error: crypto.getRandomValues() not supported.
See https://github.com/uuidjs/uuid#getrandomvalues-not-supported
```
Import it yourself at the top of your `App.js` or whatever the starting point of your app is.
### FileReader.readAsArrayBuffer
If you see:
```
Possible Unhandled Promise Rejection (id: 0):
[Error: FileReader.readAsArrayBuffer is not implemented]
```
It's likely coming from `preprocessBlob`, which this is library trys to replace.
If you're still getting this error, you likely have another copy of `pouchdb-adapter-utils` about.
Try `find . | grep pouchdb-adapter-utils` to find all internal versions in your `node_modules` directory. You may find:
```bash
$ find . | grep pouchdb-adapter-utils
./node_modules/pouchdb-adapter-websql-core/node_modules/pouchdb-adapter-utils
./node_modules/pouchdb-adapter-websql-core/node_modules/pouchdb-adapter-utils/README.md
./node_modules/pouchdb-adapter-websql-core/node_modules/pouchdb-adapter-utils/package.json
./node_modules/pouchdb-adapter-websql-core/node_modules/pouchdb-adapter-utils/LICENSE
./node_modules/pouchdb-adapter-websql-core/node_modules/pouchdb-adapter-utils/lib
./node_modules/pouchdb-adapter-websql-core/node_modules/pouchdb-adapter-utils/lib/index.es.js
./node_modules/pouchdb-adapter-websql-core/node_modules/pouchdb-adapter-utils/lib/index.js
```
This shows that `pouchdb-adapter-websql-core` is importing its own (likely older) version of
`pouchdb-adapter-utils`, bypassing our implementation of `preprocessBlob`. To stop this,
override the internal version by setting `resolutions` in `package.json`.
For example, my `pouchdb-adapter-websql-core` was locked to `pouchdb-adapter-utils`
version 7.0.0, not the 7.2.2 that's currently out (and this library is modifying).
To fix, I let `pouchdb-adapter-websql-core` use any version greater than 7.0.0
(by specifying `"^7.0.0"`).
```json
"resolutions": {
"pouchdb-adapter-websql-core/pouchdb-adapter-utils": "^7.0.0"
}
```
## Heads Up
### Sets `process.browser`
This library sets `process.browser = true`. This prevents the following error:
```javascript
TypeError: Cannot assign to read only property 'type' of object
```
This is a workaround until [this PouchDB bug fix](https://github.com/pouchdb/pouchdb/pull/8255/files)
makes it into a release, but it could have side effects elsewhere in your app.
### Overwrites `PouchDB.getAttachment`
This fix overwrites the implementation of `PouchDB.getAttachment`, to make
`opts.binary` default to `false` (instead of `true`), which tells PouchDB to use base64 strings
instead of `Blob`s and `ArrayBuffer`s. If you're still getting the following error:
```javascript
Error: Creating blobs from 'ArrayBuffer' and 'ArrayBufferView' are not supported
```
Search for other copies of this function with:
```bash
$ grep -R "opts.binary = true" node_modules/
```
If you see more than:
```
node_modules/pouchdb-core/lib/index.es.js: opts.binary = true;
node_modules/pouchdb-core/lib/index.js: opts.binary = true;
```
You may need to do something like the `FileReader.readAsArrayBuffer` fix above.
### Sets Global Base64
If `global.btoa` or `global.atob` don't exist in your app, this package will set them for you.
## Other Work
None of these (currently) work in Expo, but I used heavily in building this lib:
- https://medium.com/@duytq94/making-a-simple-note-app-with-pouchdb-in-react-native-ec4810b18a42
- https://dev.to/craftzdog/created-pouchdb-7-for-react-native-23g6
- https://github.com/badbod99/pouchdb-expo-example