KeyValueStore

The KeyValueStore class represents a key-value store, a simple data storage that is used for saving and reading data records or files. Each data record is represented by a unique key and associated with a MIME content type. Key-value stores are ideal for saving screenshots, actor inputs and outputs, web pages, PDFs or to persist the state of crawlers.

Do not instantiate this class directly, use the Apify.openKeyValueStore() function instead.

Each actor run is associated with a default key-value store, which is created exclusively for the run. By convention, the actor input and output are stored into the default key-value store under the INPUT and OUTPUT key, respectively. Typically, input and output are JSON files, although it can be any other format. To access the default key-value store directly, you can use the Apify.getValue() and Apify.setValue() convenience functions.

KeyValueStore stores its data either on local disk or in the Apify cloud, depending on whether the APIFY_LOCAL_STORAGE_DIR or APIFY_TOKEN environment variables are set.

If the APIFY_LOCAL_STORAGE_DIR environment variable is set, the data is stored in the local directory in the following files:

{APIFY_LOCAL_STORAGE_DIR}/key_value_stores/{STORE_ID}/{INDEX}.{EXT}

Note that {STORE_ID} is the name or ID of the key-value store. The default key value store has ID: default, unless you override it by setting the APIFY_DEFAULT_KEY_VALUE_STORE_ID environment variable. The {KEY} is the key of the record and {EXT} corresponds to the MIME content type of the data value.

If the APIFY_TOKEN environment variable is set but APIFY_LOCAL_STORAGE_DIR not, the data is stored in the Apify Key-value store cloud storage. Note that you can force usage of the cloud storage also by passing the forceCloud option to Apify.openKeyValueStore() function, even if the APIFY_LOCAL_STORAGE_DIR variable is set.

Example usage:

// Get actor input from the default key-value store
const input = await Apify.getValue('INPUT');

// Write actor output to the default key-value store.
await Apify.setValue('OUTPUT', { myResult: 123 });

// Open a named key-value store
const store = await Apify.openKeyValueStore('some-name');

// Write a record. JavaScript object is automatically converted to JSON,
// strings and binary buffers are stored as they are
await store.setValue('some-key', { foo: 'bar' });

// Read a record. Note that JSON is automatically parsed to a JavaScript object,
// text data returned as a string and other data is returned as binary buffer
const value = await store.getValue('some-key');

 // Delete record
await store.delete('some-key');

• KeyValueStore
  • .getValue(key) ⇒ Promise<(Object|String|Buffer)>
  • .setValue(key, value, [options]) ⇒ Promise
  • .delete() ⇒ Promise
  • .forEachKey(iteratee, [options]) ⇒ Promise

keyValueStore.getValue(key) ⇒ Promise<(Object|String|Buffer)>

Gets a value from the key-value store.

The function returns a Promise that resolves to the record value, whose JavaScript type depends on the MIME content type of the record. Records with the application/json content type are automatically parsed and returned as a JavaScript object. Similarly, records with text/plain content types are returned as a string. For all other content types, the value is returned as a raw Buffer instance.

If the record does not exist, the function resolves to null.

To save or delete a value in the key-value store, use the setValue function.

Example usage:

const store = await Apify.openKeyValueStore('my-screenshots');
const buffer = await store.getValue('screenshot1.png');

Returns: Promise<(Object|String|Buffer)> - Returns a promise that resolves to an object, string or Buffer, depending on the MIME content type of the record.

Param	Type
key	String
Unique key of the record. It can be at most 256 characters long and only consist of the following characters: [a-zA-Z0-9!-_.'()

keyValueStore.setValue(key, value, [options]) ⇒ Promise

Saves or deletes a record in the key-value store. The function returns a promise that resolves once the record has been saved or deleted.

Example usage:

const store = await Apify.openKeyValueStore('my-store');
await store.setValue('RESULTS', 'my text data', { contentType: 'text/plain' });

Beware that the key can be at most 256 characters long and only contain the following characters: a-zA-Z0-9!-_.'()

By default, value is converted to JSON and stored with the application/json; charset=utf-8 MIME content type. To store the value with another content type, pass it in the options as follows:

const store = await Apify.openKeyValueStore('my-store');
await store.setValue('RESULTS', 'my text data', { contentType: 'text/plain' });

If you set custom content type, value must be either a string or Buffer, otherwise an error will be thrown.

If value is null, the record is deleted instead. Note that the setValue() function succeeds regardless whether the record existed or not.

To retrieve a value from the key-value store, use the getValue function.

IMPORTANT: Always make sure to use the await keyword when calling setValue(), otherwise the actor process might finish before the value is stored!

Param	Type
key	String
Unique key of the record. It can be at most 256 characters long and only consist of the following characters: [a-zA-Z0-9!-_.'()
value	Object | String | Buffer
Record data, which can be one of the following values: If null, the record in the key-value store is deleted. If no options.contentType is specified, value can be any JavaScript object and it will be stringified to JSON. If options.contentType is specified, value is considered raw data and it must be either a String or Buffer. For any other value an error will be thrown.
[options]	Object
[options.contentType]	String
Specifies a custom MIME content type of the record.

keyValueStore.delete() ⇒ Promise

Removes the key-value store either from the Apify cloud storage or from the local directory, depending on the mode of operation.

keyValueStore.forEachKey(iteratee, [options]) ⇒ Promise

Iterates over key value store keys, yielding each in turn to an iteratee function. Each invocation of iteratee is called with two arguments: (item, index).

If the iteratee function returns a Promise then it is awaited before the next call. If it throws an error, the iteration is aborted and the forEachKey function throws the error.

Example usage

const keyValueStore = await Apify.openKeyValueStore();
keyValueStore.forEachKey(async (key, index) => {
  console.log(`Key at ${index}: ${key}`);
});

Param	Type
iteratee	function
A function that is called for every key in the key value store.
[options]	Object
All forEachKey() parameters are passed via an options object with the following keys:
[options.exclusiveStartKey]	string
All keys up to this one (including) are skipped from the result.