List

List

Class to handle Redis LIST type.

Behaves the same way as Array does so use it just like you would use Array, with some exceptions of course

Constructor

new List()

Source:
Example
const client = require('redis').createClient();
const types  = require('redis-type')(client);

const list = new types.List('my_list', true); // last flag for JSON=true

(async () => {

  await list.push({a: 1}, {a: 2}, {a: 3});

  console.log(await list.slice()); // get list contents

  const lastEl = await list.pop();

  console.log(await list.slice()); // [{a: 1}, {a: 2}];

  await list.setElementAt(0, lastEl);

  console.log(await list.slice()); // [{a: 3}, {a: 2}];

})();

Extends

Methods

length() → {Promise.<Number>}

Get length of a list

Source:
Example
(async () => {

  let len = await list.length();

})()

shift() → {Promise.<(Object|String)>}

Remove and get first element of the list

Source:
Example
(async () => {

  await list.push(1, 2, 3);       // fill list with values
  let first = await list.shift(); // gonna be 1 and list will contain [2, 3]

})()

pop() → {Promise.<(Object|String)>}

Remove and get last element

Source:
Example
(async () => {

  await list.push(1, 2, 3);    // fill list with values
  let last = await list.pop(); // gonna be 3 and list will contain [1, 2]

})()

unshift() → {Promise}

Prepend list with element(s)

Parameters:
Name Type Description
...els String

Element(s) to push in the beginning
Source:
Example
(async () => {

  await list.unshift(1);    // list [1]
  await list.unshift(3, 2); // list [3, 2, 1] - just like an Array in JS

})()

push() → {Promise.<Number>}

Push element(s) to the end of the list

Parameters:
Name Type Description
...els String

Element(s) to push
Source:
Example
(async () => {

  await list.push(1, 2, 3, 4); // return value: 4
  await list.push(1);          // return value: 5

})();

slice(beginopt, endopt) → {Promise.<Array>}

Get range of elements with BEGIN-END arguments

Supports just the same interface as Array does.

Parameters:
Name Type Attributes Default Description
begin Number <optional>
 0

Start point index
end Number <optional>
 null

End point index
Source:
Example
(async () => {

  await list.push(1, 2, 3, 4, 5);

  let one   = await list.slice();    // gonna be [1, 2, 3, 4, 5]
  let two   = await list.slice(1);   // gonna be [2, 3, 4, 5]
  let three = await list.slice(-2);  // gonna be [4, 5]
  let four  = await list.slice(1, 3) // gonna be [2, 3]

})()

insertAfter(key, el) → {Promise.<Number>}

Insert element after the element with given value (as String)

Parameters:
Name Type Description
key Number

Key to insert after
el String

Element to insert
Source:
Example
(async () => {

  await list.push('a', 'c', 'd');
  await list.insertAfter('a', 'b'); // returned value: 4, list: [a, b, c, d]

})()

insertBefore(key, el) → {Promise.<Number>}

Insert elenent before the elemnt with given index

Parameters:
Name Type Description
key Number

Key to insert after
el String

Element to insert
Source:
Example
(async () => {

  await list.push('a', 'c', 'd');
  await list.insertBefore('c', 'b'); // returned value: 4, list: [a, b, c, d]

})()

getElementAt(index) → {Promise.<(?String|Object)>}

Get element at the given index

  • Redis command: LINDEX
  • JavaScript analogy: none | or Array[index]
Parameters:
Name Type Description
index Number

Index to get element at
Source:
Example
(async () => {

  await list.push('a', 'b', 'c', 'd');
  let el1 = await list.getElementAt(0);   // value: 'a'
  let el2 = await list.getElementAt(-1);  // value: 'd'
  let el3 = await list.getElementAt(100); // value: null

})()

setElementAt(index, value) → {Promise.<String>}

Set element at given index

  • Redis command: LSET
  • JavaScript analogy: none | or Array[index] = value
Parameters:
Name Type Description
index Number

Index to set el at
value String

Value to set at given index
Source:
Throws:

When index is out of range (AKA greater than list.length())

Type
Error
Example
(async () => {

  await list.push('a', 'b', 'c', 'd');
  await list.setElementAt(0, 'd');     // OK, list is [d, b, c, d]
  await list.setElementAt(1, 'd');     // OK, list is [d, d, c, d]
  await list.setElementAt(2, 'd');     // OK, list is [d, d, d, d]

  await list.setElementAt(100, 'd').catch((e) => console.log(e)); // err: index out of range

})()

trim(begin, end) → {Promise.<String>}

Trim list in the given begin-end range

  • Redis command: LTRIM
  • JavaScript analogy: none; maybe Array.prototype.slice()

Indexes you specify are included (0, 0) - one element, (0, 1) - 2 elements

Parameters:
Name Type Description
begin Number

Start index
end Number

End index
Source:
Example
(async () => {

  await list.push(1, 2, 3, 4);
  await list.trim(0, -1);        // list [1,2,3,4] - the same
  await list.trim(-3, -1);       // list [2,3,4]   - from the end
  await list.trim(0, 1);         // list [2,3]     - from the start

})()

prom(method) → {function}

Return promisified version of Redis client's methods.

Uses util.promisify internally which is most native way of getting Promise. As all Redis commands have name of the key as first argument, we can and do set first argument with name/key of the storage/structure

Parameters:
Name Type Description
method String

Method to return promisified
Inherited From:
Source:

clear() → {Promise}

Remove any data type from global scope using DEL method and the key used in creation

Command might be used for debug clean-up, development purposes or for production reset of the storage

Inherited From:
Source: