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https://github.com/Meteor-Community-Packages/meteor-collection-hooks

Meteor Collection Hooks
https://github.com/Meteor-Community-Packages/meteor-collection-hooks

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Meteor Collection Hooks

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README 

        
# Meteor Collection Hooks



![Test suite](https://github.com/Meteor-Community-Packages/meteor-collection-hooks/workflows/Test%20suite/badge.svg)

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Extends Mongo.Collection with `before`/`after` hooks for `insert`, `update`, `remove`, `find`, and `findOne`.



Works across client, server or a mix. Also works when a client initiates a collection method and the server runs the hook, all while respecting the collection validators (allow/deny).



Please refer to [History.md](History.md) for a summary of recent changes.



## Getting Started



Installation:



```

meteor add matb33:collection-hooks

```



--------------------------------------------------------------------------------



### .before.insert(userId, doc)



Fired before the doc is inserted.



Allows you to modify doc as needed, or run additional

functionality



- `this.transform()` obtains transformed version of document, if a transform was

defined.



```javascript

import { Mongo } from 'meteor/mongo';

const test = new Mongo.Collection("test");



test.before.insert(function (userId, doc) {

  doc.createdAt = Date.now();

});

```



--------------------------------------------------------------------------------



### .before.update(userId, doc, fieldNames, modifier, options)



Fired before the doc is updated.



Allows you to to change the `modifier` as needed, or run additional

functionality.



- `this.transform()` obtains transformed version of document, if a transform was

defined.



```javascript

test.before.update(function (userId, doc, fieldNames, modifier, options) {

  modifier.$set = modifier.$set || {};

  modifier.$set.modifiedAt = Date.now();

});

```



__Important__: 



1. Note that we are changing `modifier`, and not `doc`.

Changing `doc` won't have any effect as the document is a copy and is not what

ultimately gets sent down to the underlying `update` method.



2. When triggering a single update targeting multiple documents using the option `multi: true` (see [Meteor documentation](https://docs.meteor.com/api/collections.html#Mongo-Collection-update)), the `before.update` hook is called once per document about to be updated, **but** the collection update called afterwards remains a single update (targetting multiple documents) with a single modifier. Hence it is not possible at the time to use `before.update` to create a specific modifier for each targeted document.



--------------------------------------------------------------------------------



### .before.remove(userId, doc)



Fired just before the doc is removed.



Allows you to to affect your system while the document is still in

existence -- useful for maintaining system integrity, such as cascading deletes.



- `this.transform()` obtains transformed version of document, if a transform was

defined.



```javascript

test.before.remove(function (userId, doc) {

  // ...

});

```



--------------------------------------------------------------------------------



### .before.upsert(userId, selector, modifier, options)



Fired before the doc is upserted.



Allows you to to change the `modifier` as needed, or run additional

functionality.



```javascript

test.before.upsert(function (userId, selector, modifier, options) {

  modifier.$set = modifier.$set || {};

  modifier.$set.modifiedAt = Date.now();

});

```



Note that calling `upsert` will always fire `.before.upsert` hooks, but will

call either `.after.insert` or `.after.update` hooks depending on the outcome of

the `upsert` operation. There is no such thing as a `.after.upsert` hook at this

time.



--------------------------------------------------------------------------------



### .after.insert(userId, doc)



Fired after the doc was inserted.



Allows you to run post-insert tasks, such as sending notifications

of new document insertions.



- `this.transform()` obtains transformed version of document, if a transform was

defined;

- `this._id` holds the newly inserted `_id` if available.



```javascript

test.after.insert(function (userId, doc) {

  // ...

});

```



--------------------------------------------------------------------------------



### .after.update(userId, doc, fieldNames, modifier, options)



Fired after the doc was updated.



Allows you to to run post-update tasks, potentially comparing the

previous and new documents to take further action.



- `this.previous` contains the document before it was updated.

  - The optional `fetchPrevious` option, when set to false, will not fetch

    documents before running the hooks. `this.previous` will then not be

    available. The default behavior is to fetch the documents.

- `this.transform()` obtains transformed version of document, if a transform was

  defined. Note that this function accepts an optional parameter to specify the

  document to transform — useful to transform previous:

  `this.transform(this.previous)`.



```javascript

test.after.update(function (userId, doc, fieldNames, modifier, options) {

  // ...

}, {fetchPrevious: true/false});

```



__Important:__ If you have multiple hooks defined, and at least one of them does

*not* specify `fetchPrevious: false`, then the documents *will* be fetched

and provided as `this.previous` to all hook callbacks. All after-update hooks

for the same collection must have `fetchPrevious: false` set in order to

effectively disable the pre-fetching of documents.



It is instead recommended to use the collection-wide options (e.g.

`MyCollection.hookOptions.after.update = {fetchPrevious: false};`).



This hook will always be called with the new documents; even if the updated document gets modified in a way were it would normally not be able to be found because of `before.find` hooks (see https://github.com/Meteor-Community-Packages/meteor-collection-hooks/pull/297).



--------------------------------------------------------------------------------



### .after.remove(userId, doc)



Fired after the doc was removed.



`doc` contains a copy of the document before it was removed.



Allows you to run post-removal tasks that don't necessarily depend

on the document being found in the database (external service clean-up for

instance).



- `this.transform()` obtains transformed version of document, if a transform was

defined.



```javascript

test.after.remove(function (userId, doc) {

  // ...

});

```



--------------------------------------------------------------------------------



### .before.find(userId, selector, options)



Fired before a find query.



Allows you to adjust selector/options on-the-fly.



```javascript

test.before.find(function (userId, selector, options) {

  // ...

});

```



__Important:__ This hook does not get called for `after.update` hooks (see https://github.com/Meteor-Community-Packages/meteor-collection-hooks/pull/297).



--------------------------------------------------------------------------------



### .after.find(userId, selector, options, cursor)



Fired after a find query.



Allows you to act on a given find query. The cursor resulting from

the query is provided as the last argument for convenience.



```javascript

test.after.find(function (userId, selector, options, cursor) {

  // ...

});

```



--------------------------------------------------------------------------------



### .before.findOne(userId, selector, options)



Fired before a findOne query.



Allows you to adjust selector/options on-the-fly.



```javascript

test.before.findOne(function (userId, selector, options) {

  // ...

});

```



--------------------------------------------------------------------------------



### .after.findOne(userId, selector, options, doc)



Fired after a findOne query.



Allows you to act on a given findOne query. The document resulting

from the query is provided as the last argument for convenience.



```javascript

test.after.findOne(function (userId, selector, options, doc) {

  // ...

});

```



--------------------------------------------------------------------------------



## Direct access (circumventing hooks)



All compatible methods have a `direct` version that circumvent any defined hooks. For example:



```javascript

collection.direct.insert({_id: "test", test: 1});

collection.direct.insertAsync({_id: "test", test: 1});

collection.direct.upsert({_id: "test", test: 1});

collection.direct.upsertAsync({_id: "test", test: 1});

collection.direct.update({_id: "test"}, {$set: {test: 1}});

collection.direct.updateAsync({_id: "test"}, {$set: {test: 1}});

collection.direct.find({test: 1});

collection.direct.findOne({test: 1});

collection.direct.findOneAsync({test: 1});

collection.direct.remove({_id: "test"});

collection.direct.removeAsync({_id: "test"});

```



--------------------------------------------------------------------------------



## Default options



As of version 0.7.0, options can be passed to hook definitions. Default options

can be specified globally and on a per-collection basis for all or some hooks,

with more specific ones having higher specificity.



Examples (in order of least specific to most specific):



```javascript

import { CollectionHooks } from 'meteor/matb33:collection-hooks';



CollectionHooks.defaults.all.all = {exampleOption: 1};



CollectionHooks.defaults.before.all = {exampleOption: 2};

CollectionHooks.defaults.after.all = {exampleOption: 3};



CollectionHooks.defaults.all.update = {exampleOption: 4};

CollectionHooks.defaults.all.remove = {exampleOption: 5};



CollectionHooks.defaults.before.insert = {exampleOption: 6};

CollectionHooks.defaults.after.remove = {exampleOption: 7};

```



Similarly, collection-wide options can be defined (these have a higher

specificity than the global defaults from above):



```javascript

import { Mongo } from 'meteor/mongo';

const testCollection = new Mongo.Collection("test");



testCollection.hookOptions.all.all = {exampleOption: 1};



testCollection.hookOptions.before.all = {exampleOption: 2};

testCollection.hookOptions.after.all = {exampleOption: 3};



testCollection.hookOptions.all.update = {exampleOption: 4};

testCollection.hookOptions.all.remove = {exampleOption: 5};



testCollection.hookOptions.before.insert = {exampleOption: 6};

testCollection.hookOptions.after.remove = {exampleOption: 7};

```



_Currently (as of 0.7.0), only `fetchPrevious` is implemented as an option, and

is only relevant to after-update hooks._



--------------------------------------------------------------------------------



## Additional notes



- Returning `false` in any `before` hook will prevent the underlying method (and

subsequent `after` hooks) from executing. Note that all `before` hooks will

still continue to run even if the first hook returns `false`.



- ~~If you wish to make `userId` available to a `find` query in a `publish`

function, try the technique detailed in this [comment](https://github.com/matb33/meteor-collection-hooks/issues/7#issuecomment-24021616)~~ `userId` is available to `find` and `findOne` queries that were invoked within a `publish` function.



- All hook callbacks have `this._super` available to them (the underlying

method) as well as `this.context`, the equivalent of `this` to the underlying

method. Additionally, `this.args` contain the original arguments passed to the

method and can be modified by reference (for example, modifying a selector in a

`before` hook so that the underlying method uses this new selector).



- It is quite normal for `userId` to sometimes be unavailable to hook callbacks

in some circumstances. For example, if an `update` is fired from the server

with no user context, the server certainly won't be able to provide any

particular userId.



- You can define a `defaultUserId` in case you want to pass an userId to the hooks but there is no context. For instance if you are executing and API endpoint where the `userId` is derived from a token. Just assign the userId to `CollectionHooks.defaultUserId`. It will be overriden by the userId of the context if it exists.



- If, like me, you transform `Meteor.users` through a [round-about way](https://github.com/matb33/meteor-collection-hooks/issues/15#issuecomment-25809919) involving

`find` and `findOne`, then you won't be able to use `this.transform()`. Instead,

grab the transformed user with `findOne`.



- When adding a hook, a handler object is returned with these methods:

  - `remove()`: will remove that particular hook;

  - `replace(callback, options)`: will replace the hook callback and options.



- If your hook is defined in common code (both server and client), it will run

twice: once on the server and once on the client. If your intention is for the

hook to run only once, make sure the hook is defined somewhere where only either

the client or the server reads it. *When in doubt, define your hooks on the

server.*



- Both `update` and `remove` internally make use of `find`, so be aware that

`find`/`findOne` hooks can fire for those methods.



- `find` hooks are also fired when fetching documents for `update`, `upsert` and `remove` hooks.



- If using the `direct` version to bypass a hook, any mongo operations done within nested 

callbacks of the `direct` operation will also by default run as `direct`. You can use the following

line in a nested callback before the operation to unset the `direct` setting: 

`CollectionHooks.directEnv = new Meteor.EnvironmentVariable(false)`



--------------------------------------------------------------------------------



## Maintainers

Maintained by [Meteor Community Packages](https://github.com/Meteor-Community-Packages) and in particular by:



- Mathieu Bouchard ([matb33](https://github.com/matb33))

- Andrew Mao ([mizzao](https://github.com/mizzao))

- Simon Fridlund ([zimme](https://github.com/zimme))

- Jan Dvorak ([StorytellerCZ](https://github.com/StorytellerCZ))



## Contributors



- Eric Dobbertin ([aldeed](https://github.com/aldeed))

- Kevin Kaland ([wizonesolutions](https://github.com/wizonesolutions))

- Jonathan James ([jonjamz](https://github.com/jonjamz))

- Dave Workman ([davidworkman9](https://github.com/davidworkman9))

- Tarang Patel ([Tarangp](https://github.com/Tarangp))

- Nathan Strauser ([nate-strauser](https://github.com/nate-strauser))

- Hubert OG ([subhog](https://github.com/subhog))

- Richard Lai ([rclai](https://github.com/rclai))

- Sahebjot Singh ([raunaqrox](https://github.com/raunaqrox))

- Aram Kocharyan ([aramk](https://github.com/aramk))

- Pierre Ozoux ([pierreozoux](https://github.com/pierreozoux))

- Tom Coleman ([tmeasday](https://github.com/tmeasday))

- Eric Jackson ([repjackson](https://github.com/repjackson))

- Koen Lav ([KoenLav](https://github.com/KoenLav))

- Chris Pravetz ([cpravetz](https://github.com/cpravetz))

- Jan Kuster ([jankapunkt](https://github.com/jankapunkt))