opensearch-docs-cn/_clients/javascript/helpers.md

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---
layout: default
title: Helper methods
parent: JavaScript client
nav_order: 2
---
# Helper methods
Helper methods simplify the use of complicated API tasks.
## Bulk helper
The bulk helper simplifies making complex bulk API requests.
### Usage
The following code creates a bulk helper instance:
```javascript
const { Client } = require('@opensearch-project/opensearch')
const documents = require('./docs.json')
const client = new Client({ ... })
const result = await client.helpers.bulk({
datasource: documents,
onDocument (doc) {
return {
index: { _index: 'example-index' }
}
}
})
console.log(result)
```
Bulk helper operations return an object with the following fields:
```json
{
total: number,
failed: number,
retry: number,
successful: number,
time: number,
bytes: number,
aborted: boolean
}
```
#### Bulk helper configuration options
When creating a new bulk helper instance, you can use the following configuration options.
| Option | Data Type | Required/Default | Description
| :--- | :--- | :--- | :---
| `datasource` | An array, async generator or a readable stream of strings or objects | Required | Represents the documents you need to create, delete, index, or update.
| `onDocument` | Function | Required | A function to be invoked with each document in the given `datasource`. It returns the operation to be executed for this document. Optionally, the document can be manipulated for `create` and `index` operations by returning a new document as part of the function's result.
| `concurrency` | Integer | Optional. Default is 5. | The number of requests to be executed in parallel.
| `flushBytes` | Integer | Optional. Default is 5,000,000. | Maximum bulk body size to send in bytes.
| `flushInterval` | Integer | Optional. Default is 30,000. | Time in milliseconds to wait before flushing the body after the last document has been read.
| `onDrop` | Function | Optional. Default is `noop`. | A function to be invoked for every document that cant be indexed after reaching the maximum number of retries.
| `refreshOnCompletion` | Boolean | Optional. Default is false. | Whether or not a refresh should be run on all affected indexes at the end of the bulk operation.
| `retries` | Integer | Optional. Defaults to the client's `maxRetries` value. | The number of times an operation is retried before `onDrop` is called for that document.
| `wait` | Integer | Optional. Default is 5,000. | Time in milliseconds to wait before retrying an operation.
### Examples
The following examples illustrate the index, create, update, and delete bulk helper operations.
#### Index
The index operation creates a new document if it doesnt exist and recreates the document if it already exists.
The following bulk operation indexes documents into `example-index`:
```javascript
client.helpers.bulk({
datasource: arrayOfDocuments,
onDocument (doc) {
return {
index: { _index: 'example-index' }
}
}
})
```
The following bulk operation indexes documents into `example-index` with document overwrite:
```javascript
client.helpers.bulk({
datasource: arrayOfDocuments,
onDocument (doc) {
return [
{
index: { _index: 'example-index' }
},
{ ...doc, createdAt: new Date().toISOString() }
]
}
})
```
#### Create
The create operation creates a new document only if the document does not already exist.
The following bulk operation creates documents in the `example-index`:
```javascript
client.helpers.bulk({
datasource: arrayOfDocuments,
onDocument (doc) {
return {
create: { _index: 'example-index', _id: doc.id }
}
}
})
```
The following bulk operation creates documents in the `example-index` with document overwrite:
```javascript
client.helpers.bulk({
datasource: arrayOfDocuments,
onDocument (doc) {
return [
{
create: { _index: 'example-index', _id: doc.id }
},
{ ...doc, createdAt: new Date().toISOString() }
]
}
})
```
#### Update
The update operation updates the document with the fields being sent. The document must already exist in the index.
The following bulk operation updates documents in the `arrayOfDocuments`:
```javascript
client.helpers.bulk({
datasource: arrayOfDocuments,
onDocument (doc) {
// The update operation always requires a tuple to be returned, with the
// first element being the action and the second being the update options.
return [
{
update: { _index: 'example-index', _id: doc.id }
},
{ doc_as_upsert: true }
]
}
})
```
The following bulk operation updates documents in the `arrayOfDocuments` with document overwrite:
```javascript
client.helpers.bulk({
datasource: arrayOfDocuments,
onDocument (doc) {
return [
{
update: { _index: 'example-index', _id: doc.id }
},
{
doc: { ...doc, createdAt: new Date().toISOString() },
doc_as_upsert: true
}
]
}
})
```
#### Delete
The delete operation deletes a document.
The following bulk operation deletes documents from the `example-index`:
```javascript
client.helpers.bulk({
datasource: arrayOfDocuments,
onDocument (doc) {
return {
delete: { _index: 'example-index', _id: doc.id }
}
}
})
```