> JavaScript API for api.ideal-postcodes.co.uk

!Cross Browser Testing
!Dependency Status

!npm bundle size (scoped)
!npm bundle size (scoped)

@ideal-postcodes/core-interface is an environment agnostic implementation of the Ideal Postcodes JavaScript API client interface.

If you are looking for the browser or Node.js client which implements this interface, please check out the downstream clients links.

Links

- API Documentation
- npm Module
- GitHub Repository
- Typings Repository
- Fixtures Repository

Downstream Clients

- Browser Client Repository
- Bundled Browser Client Repository
- Node.js Client Repository
- Axios-backed Client Repository

Documentation

- Usage & Configuration
- Quick Methods
- Resource Methods
- Error Handling

$3

#### Usage

To install, pick one of the following based on your platform

``bash


For browser client

npm install @ideal-postcodes/core-browser

For node.js client

npm install @ideal-postcodes/core-node

For generic interface (you need to supply your own HTTP agent)

npm install @ideal-postcodes/core-interface
`

Instantiate a client with

`javascript
import { Client } from "@ideal-postcodes/core-";

const client = new Client({ api_key: "iddqd" });

// Only api_key is required by core-node and core-browser - all others are optional
// The agentless interface requires explicit configuration
`

Client configuration options

---

#### Quick Methods

The library exposes a number of simple methods to get at the most common tasks when interacting with the API

- Lookup a Postcode
- Search for an Address
- Search for an Address by UDPRN
- Search for an Address by UMPRN
- Check Key Usability

#### Lookup a Postcode

Return addresses associated with a given postcode

Invalid postcodes (i.e. postcode not found) return an empty array []

`javascript
import { lookupPostcode } from "@ideal-postcodes/core-browser";

const postcode = "id11qd";

lookupPostcode({ client, postcode }).then(addresses => {
console.log(addresses);
{
postcode: "ID1 1QD",
line_1: "2 Barons Court Road",
// ...etc...
}
});
`

lookupPostcode docs

#### Search for an Address

Return addresses associated with a given query

`javascript
import { lookupAddress } from "@ideal-postcodes/core-browser";

const query = "10 downing street sw1a";

lookupAddress({ client, query }).then(addresses => {
console.log(addresses);
{
postcode: "SW1A 2AA",
line_1: "Prime Minister & First Lord Of The Treasury",
// ...etc...
}
});
`

lookupAddress docs

#### Search for an Address by UDPRN

Return address for a given udprn

Invalid UDPRN will return null

`javascript
import { lookupUdprn } from "@ideal-postcodes/core-browser";

const udprn = 23747771;

lookupUdprn({ client, udprn }).then(address => {
console.log(address);
{
postcode: "SW1A 2AA",
line_1: "Prime Minister & First Lord Of The Treasury",
// ...etc...
}
});
`

lookupUdprn docs

#### Search for an Address by UMPRN

Return address for a given umprn

Invalid UMPRN will return null

`javascript
import { lookupUmprn } from "@ideal-postcodes/core-browser";

const umprn = 50906066;

lookupUmprn({ client, umprn }).then(address => {
console.log(address);
{
postcode: "CV4 7AL",
line_1: "Room 1, Block 1 Arthur Vick",
// ...etc...
}
});
`

lookupUmprn docs

#### Check Key Usability

Check if a key is currently usable

`javascript
checkKeyUsability({ client }).then((key) => {
console.log(key.available); // => true
});
`

checkKeyUsability docs

---

#### Resources

Resources defined in the API documentation are exported by the library. Each resource exposes a method (#retrieve, #list, etc) which maps to a resource action.

These methods expose a low level interface to execute HTTP requests and observe HTTP responses. They are ideal if you have a more complex query or usecase where low level access would be useful.

Resource methods return a promise with a HTTP response object type.

#### Retrieve

Requesting a resource by ID (e.g. a postcode lookup for postcode with ID "SW1A 2AA") maps to the #retrieve method.

The first argument is the client object. The second is the resource ID. The last argument is an object which accepts header and query attributes that map to HTTP header and the request querystring.

`javascript
resourceName.retrieve(client, "id", {
query: {
api_key: "foo",
tags: "this,that,those",
licensee: "sk_99dj3",
},
header: {
"IDPC-Source-IP": "8.8.8.8",
},
timeout: 5000,
});
`

#### List

Requesting a resource endpoint (e.g. an address query to /addresses) maps to the #list method.

`javascript
resourceName.list(client, {
query: {
api_key: "foo",
query: "10 downing street",
},
header: {
"IDPC-Source-IP": "8.8.8.8",
},
timeout: 5000,
});
`

The first argument is the client. The second is an object which accepts header and query attributes that map to HTTP header and the request querystring.

#### Custom Actions

Some endpoints are defined as custom actions, e.g. /keys/:key/usage. These can be invoked using the name of the custom action.

E.g. for key usage data extraction

`javascript
keys.usage(client, api_key, {
query: {
tags: "checkout,production",
},
header: {
Authorization: 'IDEALPOSTCODES user_token="foo"',
},
timeout: 5000,
});
`

---

#### Resource Methods

Listed below are the available resources exposed by the library:

- Postcodes
- Addresses
- Autocomplete
- UDPRN
- UMPRN
- Keys

#### Postcodes

Retrieve addresses for a postcode.

`javascript
import { postcodes } from "@ideal-postcodes/core-browser";
postcodes
.retrieve(client, "SW1A2AA", {
header: {
Authorization: 'IDEALPOSTCODES api_key="iddqd"',
},
})
.then((response) => {
const addresses = response.body.result;
})
.catch((error) => logger(error));
`

Postcode resource HTTP API documentation

Postcode resource docs

#### Addresses

Search for an address

`javascript
import { addresses } from "@ideal-postcodes/core-browser";

addresses
.list(client, {
query: {
query: "10 Downing street",
},
header: {
Authorization: 'IDEALPOSTCODES api_key="iddqd"',
},
})
.then((response) => {
const addresses = response.body.result.hits;
})
.catch((error) => logger(error));
`

Address resource HTTP API documentation

Address resource client docs

#### Autocomplete

Autocomplete an address given an address partial

`javascript
import { autocomplete } from "@ideal-postcodes/core-browser";

autocomplete
.list(client, {
query: {
query: "10 Downing stre",
},
header: {
Authorization: 'IDEALPOSTCODES api_key="iddqd"',
},
})
.then((response) => {
const suggestions = response.body.result.hits;
})
.catch((error) => logger(error));
`

Autocomplete resource HTTP API documentation

Autocomplete resource client docs

#### UDPRN

Retrieve an address given a UDPRN

`javascript
import { udprn } from "@ideal-postcodes/core-browser";

udprn
.retrieve(client, "12345678", {
header: {
Authorization: 'IDEALPOSTCODES api_key="iddqd"',
},
})
.then((response) => {
const address = response.body.result;
})
.catch((error) => logger(error));
`

UDPRN resource HTTP API documentation

UDPRN resource client docs

#### UMPRN

Retrieve a multiple residence premise given a UMPRN

`javascript
import { umprn } from "@ideal-postcodes/core-browser";

umprn
.retrieve(client, "87654321", {
header: {
Authorization: 'IDEALPOSTCODES api_key="iddqd"',
},
})
.then((response) => {
const address = response.body.result;
})
.catch((error) => logger(error));
`

UMPRN resource HTTP API documentation

UMPRN resource client docs

#### Keys

Find out if a key is available

`javascript
import { keys } from "@ideal-postcodes/core-browser";

keys
.retrieve(client, "iddqd", {})
.then((response) => {
const { available } = response.body.result;
})
.catch((error) => logger(error));
`

Method docs

Get private information on key (requires user_token)

`javascript
import { keys } from "@ideal-postcodes/core-browser";

keys
.retrieve(client, "iddqd", {
header: {
Authorization: 'IDEALPOSTCODES user_token="secret-token"',
},
})
.then((response) => {
const key = response.body.result;
})
.catch((error) => logger(error));
`

Method docs

Get key usage data

`javascript
import { keys } from "@ideal-postcodes/core-browser";

keys
.usage(client, "iddqd", {
header: {
Authorization: 'IDEALPOSTCODES user_token="secret-token"',
},
})
.then((response) => {
const key = response.body.result;
})
.catch((error) => logger(error));
`

Method docs

Keys resource HTTP API documentation

Key resource client docs

---

#### Error Handling

This library exports a static variable errors which contains custom error constructors that wrap specific API errors. These constructors can be used to test for specific cases using the instanceof operator.

For example:

`javascript
const { IdpcInvalidKeyError } = Client.errors;

try {
const addresses = await lookupPostcode({ client, postcode: "SW1A2AA" });
} catch (error) {
if (error instanceof IdpcInvalidKeyError) {
// Handle an invalid key error
}
}
`

Not all specific API errors will be caught. If a specific API error does not have an error constructor defined, a more generic error (determined by the HTTP status code) will be returned.

For example:

`javascript
import {
IdpcRequestFailedError,
lookupPostcode,
} from "@ideal-postcodes/core-browser";

try {
const addresses = await lookupPostcode({ client, postcode: "SW1A2AA" });
} catch (error) {
if (error instanceof IdpcRequestFailedError) {
// IdpcRequestFailedError indicates a 402 response code
// Possibly the key balance has been depleted
}
}
`

You may view a sketch of the error prototype chain.

---

$3

For more advanced use cases, this core-interface library provides:

- Class implementations for Ideal Postcodes API errors that inherit from Error
- A parser that converts raw error data into one of these error instances

#### Error Usage

Aside from inspecting the HTTP request status code and/or JSON body response codes, you may also test for specific error instances.

Errors that don't inherit from IdealPostcodesError would indicate some kind of error external to the API (e.g. bad network, request timeout).

`javascript
import { errors } from "@ideal-postcodes/core-browser";
const { IdpcPostcodeNotFoundError } = errors;

// Handle a specific error
if (error instanceof IdpcPostcodeNotFoundError) {
// You got yourself an invalid API Key
}

// Alternatively use a switch statement
switch (true) {
case error instanceof IdpcPostcodeNotFoundError:
// You got yourself an invalid API Key
default:
// Default error handling path
}
`

#### Error Prototype Chain

All errors inherit from JavaScript's Error prototype.

Errors are grouped by HTTP status code classes.

Specific errors may be supplied for the following reasons:

- Convenience. They are frequently tested for (e.g. invalid postcode, postcode not found)
- Useful for debug purposes during the implementation stages

`javascript
Prototype Chain

Parent class inherits from Javascript Error. Returned if no JSON Response body


IdealPostcodesError < Error
|
|- IdpcApiError # Generic Error Class, returned if JSON response body present
|
|- IdpcBadRequestError # 400 Errors
|- IdpcUnauthorisedError # 401 Errors
|- IdpcRequestFailedError # 402 Errors
| |- IdpcBalanceDepletedError
| |- IdpcLimitReachedError
|
|- IdpcResourceNotFoundError # 404 Errors
| |- IdpcPostcodeNotFoundError
| |- IdpcKeyNotFoundError
| |- IdpcUdprnNotFoundError
| |- IdpcUmprnNotFoundError
|
|- IdpcServerError # 500 Errors
`

#### Error Parser

The error parser consumes a HTTP API response and returns the correct error instance.

`javascript
import { errors } from "@ideal-postcodes/core-browser";
const { parse, IdpcPostcodeNotFoundError } = errors;

const invalidPostcodeUrl = "https://api.ideal-postcodes.co.uk/v1/postcodes/bad_postcode?api_key=iddqd"

const response = await fetch(invalidPostcodeUrl);

// Generate an error object if present, otherwise returns undefined
const error = parse(response);

// Handle the error
if (error instanceof IdpcPostcodeNotFoundError) {...}
`

Test

`bash
npm test
``

Licence

MIT