HappyGAPI

A Clojure library for calling Google APIs; gsheets, drive, bigquery, and so on.

Rationale

HappyGAPI is a bunch of generated functions (as code, not macros) for calling GAPI, so that your editor can help you (autocomplete, help documentation, and arg checking).

HappyGAPI generates source code:

Navigate to source
See all available resources and methods
Clear exception stack traces on failure
The function doc-strings contain a description, a link to online docs, and example inputs (TODO: is this true?)
Needs to be regenerated to discovery API updates

HappyGAPI accepts data instead of objects. Data composes flexibly and is straight-forward to construct.

Oauth2 works "out of the box" for standalone, and with minimal configuration in a web server.

The discovery of GAPIs was inspired by clj-gapi. See Google API discovery: https://developers.google.com/discovery/v1/getting_started

Usage

Add the dependency to the project file:

Require happygapi.<<api>>.<<resource>> in the code:

(ns my.ns
  (:require [happygapi.sheets.spreadsheets :as gsheets]
            [happy.oauth2-credentials :as credentials]))

Browse all available endpoints from your editor:

(gsheets/)

Get help documentation in your editor for arguments:

(gsheets/get$)

happygapi.sheets.spreadsheets/get$
[auth parameters]

https://developers.google.com/sheets/api/reference/rest/v4/spreadsheets/get

Required parameters: spreadsheetId

Optional parameters: ranges, includeGridData

Returns the spreadsheet at the given ID.

Call it:

(gsheets/get$ (credentials/auth!) {:spreadsheetId "xyz"})

(gsheets/values-batchUpdate$ (credentials/auth!)
                             {:spreadsheetId spreadsheet-id}
                             {:valueInputOption "USER_ENTERED"
                              :data             [{:range  "Sheet1"
                                                  :values [[1 2 3]
                                                           [4 5 6]]}]})

Functions are generated according to this pattern:

(happygapi.<<api>>.<<resource>>/<<?subresource(s)>>-<<method>>$ auth params ?body)

Where auth is a map to apply to the request, params and body align with REST documentation. For example see batchUpdate.

The json-schema files are written as edn to resources. I plan to add json-schema validation to the body soon.

Authorization

The auth argument can be one of:

{}                                                   ; anonymous
{:query-params {"key" api-key}}                      ; api-key
{:headers {"Authorization" (str "Bearer " api-key)}} ; api-key in header is better (TODO: check)
{:headers {"Authorization" (str "Bearer " token)}}   ; oauth2 token

The auth argument gets merged into the request. You can specify additional request options if you want to.

To participate in oauth2 you need to fetch and store tokens.

To create an app in the Google Console, follow Setting up OAuth 2.0. When setting up the app credentials, add http://localhost/redirect to the authorized redirect URIs, and add yourself as a test user.

There are two methods for obtaining a token:

User redirects, which prompt a user to authorize your app. Download the secret.json from the Google Console. Do not add this file to source control, keep it secured. This method is suitable if you want users to grant your app access to their data.
Service account private key (suitable for server to server). Create a Service account and download a service.json key file. Do not add this file to source control, keep it secured. This method is suitable for automated jobs.

The happy.oauth2-credentials namespace provides a convenient way to manage authorization. By default, it tries to read secret.json or service.json from disk in the current directory. You can pass in configuration map of the same shape instead. happy.oauth2-credentials stores tokens on disk. If you want to use HappyGAPI in a web app, you should instead store and fetch tokens from your database. This can be done by calling init! with a fetch and store function, or by creating your own implementation of auth!.

The happy.oauth2-capture-redirect namespace provides a listener to capture a code when the user is redirected to your site from the oauth2 provider. If you use it, you will need to include ring as a dependency. Web applications should instead define a route to capture the code.

The happy.oauth2 namespace provides generic functions to support oauth2 authorization so that you can assemble only the parts you need.

Retries

HappyGAPI leaves retries up to the consuming application. However, if you are doing many requests, it is likely you will want to retry failed requests, as failures can happen for a variety of availability reasons.

Providing your own retry strategy can be done by redefining the happy.util/get-response behavior:

(defmacro with-get-response-retries
  [& body]
  `(let [get-response# @#'hu/get-response]
     (with-redefs [hu/get-response (fn get-response-with-retries# [& args#]
                                     (again/with-retries [2000 5000 10000 15000]
                                                         (apply get-response# args#)))]
       ~@body)))

Now you can wrap calls using with-get-response-retries:

(with-get-response-retries
  (g.sheets/create$ (credentials/auth!)
                    {}
                    {:properties {:title title}}))

This example uses the "again" library.

Contributing

Issues, pull requests, and suggestions are welcome.

Updating

Building pulls down the latest schema. You can build it yourself if this library has not been updated in a while. Please email me if you'd like me to push an updated version.

Building

The api namespaces can be generated by running happy.lion/-main

lein run

Testing

To run the tests you need to download secret.json from the Google console.

lein test

Deploying

lein release clojars

License

This program and the accompanying materials are made available under the terms of the Eclipse Public License 2.0 which is available at http://www.eclipse.org/legal/epl-2.0.

This Source Code may also be made available under the following Secondary Licenses when the conditions for such availability set forth in the Eclipse Public License, v. 2.0 are satisfied: GNU General Public License as published by the Free Software Foundation, either version 2 of the License, or (at your option) any later version, with the GNU Classpath Exception which is available at https://www.gnu.org/software/classpath/license.html.

echeran/happygapi