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List keys

To list all the keys in your KV namespace, call the list() method of the KV binding on any KV namespace you have bound to your Worker code:

env.NAMESPACE.list();

The list() method returns a promise you can await on to get the value.

Example

An example of listing keys from within a Worker:

export default {
  async fetch(request, env, ctx) {
    try {
      const value = await env.NAMESPACE.list();


      return new Response(JSON.stringify(value.keys), {
        status: 200
      });
    }
    catch (e)
    {
      return new Response(e.message, {status: 500});
    }
  },
};

Reference

The following method is provided to list the keys of KV:

list() method

To list all the keys in your KV namespace, call the list() method of the KV binding on any KV namespace you have bound to your Worker code:

env.NAMESPACE.list(options?)

Parameters

  • options: { prefix?: string, limit?: string, cursor?: string }
    • An object with attributes prefix (optional), limit (optional), or cursor (optional).
      • prefix is a string that represents a prefix you can use to filter all keys.
      • limit is the maximum number of keys returned. The default is 1,000, which is the maximum. It is unlikely that you will want to change this default but it is included for completeness.
      • cursor is a string used for paginating responses.

Response

  • response: Promise<{ keys: { name: string, expiration?: number, metadata?: object }[], list_complete: boolean, cursor: string }>
    • A Promise that resolves to an object containing keys, list_complete, and cursor attributes.
      • keys is an array that contains an object for each key listed. Each object has attributes name, expiration (optional), and metadata (optional). If the key-value pair has an expiration set, the expiration will be present and in absolute value form (even if it was set in TTL form). If the key-value pair has non-null metadata set, the metadata will be present.
      • list_complete is a boolean, which will be false if there are more keys to fetch, even if the keys array is empty.
      • cursor is a string used for paginating responses.

The list() method returns a promise which resolves with an object that looks like the following:

{
  "keys": [
    {
      "name": "foo",
      "expiration": 1234,
      "metadata": { "someMetadataKey": "someMetadataValue" }
    }
  ],
  "list_complete": false,
  "cursor": "6Ck1la0VxJ0djhidm1MdX2FyD"
}

The keys property will contain an array of objects describing each key. That object will have one to three keys of its own: the name of the key, and optionally the key's expiration and metadata values.

The name is a string, the expiration value is a number, and metadata is whatever type was set initially. The expiration value will only be returned if the key has an expiration and will be in the absolute value form, even if it was set in the TTL form. Any metadata will only be returned if the given key has non-null associated metadata.

If list_complete is false, there are more keys to fetch, even if the keys array is empty. You will use the cursor property to get more keys. Refer to Pagination for more details.

Consider storing your values in metadata if your values fit in the metadata-size limit. Storing values in metadata is more efficient than a list() followed by a get() per key. When using put(), leave the value parameter empty and instead include a property in the metadata object:

await NAMESPACE.put(key, "", {
  metadata: { value: value },
});

Changes may take up to 60 seconds (or the value set with cacheTtl of the get() or getWithMetadata() method) to be reflected on the application calling the method on the KV namespace.

Guidance

List by prefix

List all the keys starting with a particular prefix.

For example, you may have structured your keys with a user, a user ID, and key names, separated by colons (such as user:1:<key>). You could get the keys for user number one by using the following code:

export default {
  async fetch(request, env, ctx) {
    const value = await env.NAMESPACE.list({ prefix: "user:1:" });
    return new Response(value.keys);
  },
};

This will return all keys starting with the "user:1:" prefix.

Ordering

Keys are always returned in lexicographically sorted order according to their UTF-8 bytes.

Pagination

If there are more keys to fetch, the list_complete key will be set to false and a cursor will also be returned. In this case, you can call list() again with the cursor value to get the next batch of keys:

const value = await NAMESPACE.list();


const cursor = value.cursor;


const next_value = await NAMESPACE.list({ cursor: cursor });

Checking for an empty array in keys is not sufficient to determine whether there are more keys to fetch. Instead, use list_complete.

It is possible to have an empty array in keys, but still have more keys to fetch, because recently expired or deleted keys ↗ must be iterated through but will not be included in the returned keys.

When de-paginating a large result set while also providing a prefix argument, the prefix argument must be provided in all subsequent calls along with the initial arguments.

Optimizing storage with metadata for list() operations

Consider storing your values in metadata if your values fit in the metadata-size limit. Storing values in metadata is more efficient than a list() followed by a get() per key. When using put(), leave the value parameter empty and instead include a property in the metadata object:

await NAMESPACE.put(key, "", {
  metadata: { value: value },
});

Other methods to access KV

You can also list keys on the command line with Wrangler or with the REST API.

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