@aws-sdk/s3-presigned-post


This package provide a function generating URL and fields. Users without AWS credentials can use the URL and fields to
to make a POST request to S3. The documentation for the server side feature can be found in S3 API Reference. Please read related sections for more context.

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JavaScript Example:

``javascript
const { createPresignedPost } = require("@aws-sdk/s3-presigned-post");
const { S3Client } = require("@aws-sdk/client-s3");
`

ES6 Example

`javascript
import { createPresignedPost } from "@aws-sdk/s3-presigned-post";
import { S3Client } from "@aws-sdk/client-s3";
`

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You can optionally attach a policy to a presigned post. It specifies a list of conditions that the request must meet.
For example:

`typescript
const Conditions = [{ acl: "bucket-owner-full-control" }, { bucket: "johnsmith" }, ["starts-with", "$key", "user/eric/"]];
`

Visit S3 POST documentation
for supported policy elements. If you include a condition, you must specify the valid value in the Fields parameter
as well. A value will not be added automatically to the fields dictionary according to the conditions.

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Users can generate required url and fields for POST request:

`typescript
const client = new S3Client({ region: "us-west-2" });
const Bucket = "johnsmith";
const Key = "user/eric/1";
const Fields = {
acl: "bucket-owner-full-control",
};
const { url, fields } = await createPresignedPost(client, {
Bucket,
Key,
Conditions,
Fields,
Expires: 600, //Seconds before the presigned post expires. 3600 by default.
});
`

The Bucket, Key and other values in Fields must meet the conditions specified in Conditions. The Key can also
contain ${filename} that will be automatically replaced by the name of the file provided. See the S3 reference
for more information.

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You can also post a file with HTML form:

`html








In Node.js, use form-data package to post a file:

`typescript
const { createReadStream } = require("fs");
const FormData = require("form-data");

const form = new FormData();
Object.entries(fields).forEach(([field, value]) => {
form.append(field, value);
});
form.append("file", createReadStream("path/to/a/file"));
form.submit(url, (err, res) => {
//handle the response
});
``