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Make sure to first setup the repository tooling to ease your journey!

This repository leverages openapi-generator to generate API clients.

Find a template to start with​

Provided templates should be a good starting point to generate a client but make sure to implement the Algolia requirements to make it work properly.

You can pick a default template on the openapi-generator’s “generators” page

Extract the template locally​

apic exec java "yarn openapi-generator-cli author template -g <templateName> -o templates/<languageName>"

Example for the JavaScript client with the typescript-node template:

apic exec java "yarn openapi-generator-cli author template -g typescript-node -o templates/javascript/"

Update the generator config​

Please read the add a new client guide for information on how to structure your new client and setup the configuration files.

Algolia requirements​

caution

DX is key.

We require the generated API clients to have an up-to-date usage with their ecosystem, make sure to provide correct tooling to lint and format generated code.

Strip code​

The default generators includes a lot of features that won’t be used with the Algolia engine:

  • Multiple authentication methods: appId/apiKey are the only authentication methods, located in the requests headers.
  • Built-in transporters: A retry strategy is required to target the DSNs of an appId, along with other transporter details listed below.
  • File support, payload format etc.: Requests only require JSON support to communicate with the engine.

Init method​

By default, OpenAPI will put the AppId and ApiKey in every method parameters, but the clients needs to be initialized with those values and put them in the header of every requests, with the right hosts.

The constructor of the client can be edited (from the .mustache files) to accept and store those values.

Retry strategy​

The retry strategy cannot be generated and needs to be implemented outside of the generated client folder. You can achieve this by creating a utils (or any naming that you find relevant) folder and add a transporter and retry strategy logic to it.

Different client hosts​

Some Algolia clients (search and recommend) targets the default appId host (${appId}-dsn.algolia.net, ${appId}.algolia.net, etc.), while clients like personalization have their own regional host (eu | us | de).

As the generator does not support reading servers in a spec file yet, hosts methods and variables are extracted with a custom script and create variables for you to use in the mustache templates, read more here.

User Agent​

The header ‘User-Agent’ must respect a strict pattern of a base, client, plus additional user defined segments:

base: `Algolia for <language> (<apiVersion>)`
client: `; <clientName> (<clientVersion>)`
segment: `; <Description> ([version])`

The version is optional for segments.

The resulting User Agent is the concatenation of base, then client and all the segments in any order.

For example, if we have:

  • base: Algolia for Java (4.0.0)
  • client: ; Search (4.0.0)
  • segment:
    • ; JVM (11.0.14)
    • ; experimental
    • ; test (8.0.0-beta)

Then the resulting User Agent is (the order is arbitrary):

Algolia for Java (4.0.0); JVM (11.0.14); Search (4.0.0); experimental ; test (8.0.0-beta)

You can take a look at the Java implementation here.

The User-Agent MUST match the following regular expression:

^Algolia for <LANGUAGE> \\(\\d+\\.\\d+\\.\\d+(-?.*)?\\)(; [a-zA-Z. ]+ (\\(\\d+((\\.\\d+)?\\.\\d+)?(-?.*)?\\))?)*(; <CLIENT> (\\(\\d+\\.\\d+\\.\\d+(-?.*)?\\)))(; [a-zA-Z. ]+ (\\(\\d+((\\.\\d+)?\\.\\d+)?(-?.*)?\\))?)*$

The function MUST be named addAlgoliaAgent because of JavaScript exception that doesn’t allow custom User-Agent in the header, and must use x-algolia-agent for JavaScript.

Dependencies​

You can use any dependency you want to create the client, it can be Json parser or HTTP client, but it’s important to never expose those dependencies through the client, meaning:

  • a function cannot return an object from a dependency
  • a function cannot accept an object from a dependency as a parameter
  • and so on

It matters because when a dependency is exposed, a breaking change from our deps can affect the user code while the API client is still working correctly (because they have to use the dependency in their code), and that prevent us from upgrading our deps. In some languages it also requires the user to add our internal dependencies to his build system, which is very inconvenient and our clients should always be standalone.

To achieve this you can create interfaces that can be exposed, and wrap the method you want to be exposed, for an HTTP client for example.

useReadTransporter​

Some methods of our REST API send POST requests via the read transporter of the API client, to reflect this implementation, we provide a variable in the template for you to distinguish those methods, called vendorExtensions.x-use-read-transporter.

This option is provided at the spec level and used in the mustache files.

You can take a look at the implementation over all clients, in this pull request.

requestOptions​

Every methods of every clients provide a parameter that does not exist in the REST API, called requestOptions.

This parameter MUST be the last parameter of a method, and allow a user to override/merge additional query parameters or headers with the transporter ones.

Requesters​

The requester needs to be configurable and capable to be overwritten to use a user defined requester. The default requester must be the classic HTTP requester, and it’s possible to provide other alternatives like an Echo Requester that just send the request back.

Logger​

TODO: information

Generated file banner​

The banner SHOULD be added at the very top of every generated files, to avoid confusion for our users, but also redirect them to the api-clients-automation monorepo, where the contribution happens.

To do so, a generationBanner variable is available on every mustache templates, see the initial implementation for more context.