graphql-compose-connection
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Plugin for `graphql-compose` which provide a connection resolver for types.
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# graphql-compose-connection
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This is a plugin for [graphql-compose](https://github.com/graphql-compose/graphql-compose) family, which adds to the ObjectTypeComposer `connection` resolver.
Live demo: [https://graphql-compose.herokuapp.com/](https://graphql-compose.herokuapp.com/)
This package completely follows to Relay Cursor Connections Specification (<https://relay.dev/graphql/connections.htm>).
Besides standard connection arguments `first`, `last`, `before` and `after`, also added significant arguments:
- `filter` arg - for filtering records
- `sort` arg - for sorting records. Build in mechanism allows sort by any unique indexes (not only by id). Also supported compound sorting (by several fields).
[CHANGELOG](https://github.com/graphql-compose/graphql-compose-connection/blob/master/CHANGELOG.md)
## Installation
```bash
npm install graphql graphql-compose graphql-compose-connection --save
```
Modules `graphql` and `graphql-compose` are in `peerDependencies`, so should be installed explicitly in your app. They should not installed as submodules, cause internally checks the classes instances.
## Example
Implementation details of `findManyResolver` and `countResolver` can be found in [this file](./src/__mocks__/User.ts).
```js
import { prepareConnectionResolver } from 'graphql-compose-connection';
import { UserTC, findManyResolver, countResolver } from './user';
prepareConnectionResolver(userTC, {
findManyResolver,
countResolver,
sort: {
// Sorting key, visible for users in GraphQL Schema
_ID_ASC: {
// Sorting value for ORM/Driver
value: { _id: 1 },
// Field names in record, which data will be packed in `cursor`
// edges {
// cursor <- base64(cursorData), for this example `cursorData` = { _id: 334ae453 }
// node <- record from DB
// }
// By this fields MUST be created UNIQUE index in database!
cursorFields: ['_id'],
// If for connection query provided `before` argument with above `cursor`.
// We should construct (`rawQuery`) which will be point to dataset before cursor.
// Unpacked data from `cursor` will be available in (`cursorData`) argument.
// PS. All other filter options provided via GraphQL query will be added automatically.
// ----- [record] ----- sorted dataset, according to above option with `value` name
// ^^^^^ `rawQuery` should filter this set
beforeCursorQuery: (rawQuery, cursorData, resolveParams) => {
if (!rawQuery._id) rawQuery._id = {};
rawQuery._id.$lt = cursorData._id;
},
// Constructing `rawQuery` for connection `after` argument.
// ----- [record] ----- sorted dataset
// ^^^^^ `rawQuery` should filter this set
afterCursorQuery: (rawQuery, cursorData, resolveParams) => {
if (!rawQuery._id) rawQuery._id = {};
rawQuery._id.$gt = cursorData._id;
},
},
_ID_DESC: {
value: { _id: -1 },
cursorFields: ['_id'],
beforeCursorQuery: (rawQuery, cursorData, resolveParams) => {
if (!rawQuery._id) rawQuery._id = {};
rawQuery._id.$gt = cursorData._id;
},
afterCursorQuery: (rawQuery, cursorData, resolveParams) => {
if (!rawQuery._id) rawQuery._id = {};
rawQuery._id.$lt = cursorData._id;
},
},
// More complex sorting parameter with 2 fields
AGE_ID_ASC: {
value: { age: 1, _id: -1 },
// By these fields MUST be created COMPOUND UNIQUE index in database!
cursorFields: ['age', '_id'],
beforeCursorQuery: (rawQuery, cursorData, resolveParams) => {
if (!rawQuery.age) rawQuery.age = {};
if (!rawQuery._id) rawQuery._id = {};
rawQuery.age.$lt = cursorData.age;
rawQuery._id.$gt = cursorData._id;
},
afterCursorQuery: (rawQuery, cursorData, resolveParams) => {
if (!rawQuery.age) rawQuery.age = {};
if (!rawQuery._id) rawQuery._id = {};
rawQuery.age.$gt = cursorData.age;
rawQuery._id.$lt = cursorData._id;
},
}
},
});
```
<img width="1249" alt="screen shot 2016-07-20 at 12 20 08" src="https://cloud.githubusercontent.com/assets/1946920/16976899/67a5e0f8-4e74-11e6-87e5-fc4574deaaab.png">
## Used in plugins
[graphql-compose-mongoose](https://github.com/graphql-compose/graphql-compose-mongoose) - converts mongoose models to graphql types
## License
[MIT](https://github.com/graphql-compose/graphql-compose-connection/blob/master/LICENSE.md)