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17.4.0 • Public • Published


API Snippets makes it easy to work with Mojaloop's APIs, by breaking down the definitions into reusable, composable chunks.

Swagger UI Api Preview



Install the snippet library

  npm install @mojaloop/api-snippets --save-dev

Install the reference resolving library

  npm install @redocly/openapi-cli --save-dev

Modify swagger file to reference api-snippets.


  $ref: /path/to/node_modules/@mojaloop/api-snippets/fspiop/v1_1/openapi3/components/schemas/Money.yaml

Render and resolve the references.

  openapi bundle --output openapi.yaml --ext yaml openapi_template.yaml

Validate the result file.

  swagger-cli validate api_render.yaml

Quick Demonstration



The snippets specification is previewable using swagger-ui. Swagger-UI files are found in docs/dist/. Github pages uses the main branch docs/ folder to build the page found at https://docs.mojaloop.io/api-snippets/

Dev Tools

To create snippets the tool found at https://redoc.ly/docs/cli/#installation-and-usage was used to break up large specification files. Some manual edits to the paths are needed to format the files.

TODO: Add more detailed instructions for this workflow.

  • npm install -g @redocly/openapi-cli
  • openapi split fspiop-rest-v1.1-openapi3-snippets.yaml --outDir ./fspiop/v1_1


  1. Do we need to support both Swagger 2.0 and Open Api 3?

Suggestions for Improvement

  1. Avoid storing generated files in the repo. All artifacts should be generated during build time (when building docker image).
  2. Organize snippets into folders based on their usage (i.e. bulk API, participants API, etc)

DTO TypeScript definitions for snippets

Data Transfer Object description

The reason to have DTO is to allow separation between data transfer and data access phases.

From OpenAPI definition perspective api-snippets module allows building api.yaml definitions using a structured set of building blocks - the snippets.

From microservices implementation point of view there is a need to have similar mechanism to allow declaring aggregated api data transfer types using basic types. These basic types reflect api-snippets definitions at implementation language level of TypeScript

Example of payload definition

Let assume we want to define a new type to represent the http request POST payload body with two properties: requestId and amount using already defined in api-snippets basic types: CorrelationId and Money

import { Schemas } from '@mojaloop/api-snippets/v1_0'

interface ExampleTransferRequest {
  requestId: Schemas.CorrelationId
  amount: Schemas.Money

structure of @mojaloop/api-snippets TypeScript type system module

api-snippets OpenAPI definitions are grouped in three sections/folders with corresponding Javascript sub-modules

OpenApi TypeScript
v1.0/openapi3/ v1_0
v1.1/openapi3/ v1_1
thirdparty/opeanapi3 thirdparty

The same structure is kept in TypesScript module, but with some handy shortcuts: there are no openapi3/schemas sub-folders/sub-modules

To use the types defined for CorrelationId and Money snippets

  • v1.0/openapi3/schemas/CorrelationId.yaml
  • v1.0/openapi3/schemas/Money.yaml

You can import them in a such short way:

import { Schemas } from `@mojaloop/api-snippets/v1_0`

interface ExampleTransferRequest {
  requestId: Schemas.CorrelationId
  amount: Schemas.Money

You can also have access to full openapi interface auto generated by openapi-typescript including paths & components

import { openapi } from `@mojaloop/api-snippets/v1_0`

interface ExampleTransferRequest {
  requestId: openapi.components['schemas']['CorrelationId']
  amount: openapi.components['schemas']['Money']

DTO auto generation

For development of api-snippets module please use this mantra

npm run build

It will generate OpenAPI specifications from snippets, then generate DTO from these snippets and finally generate javascript code

Auto generation for micro services

When developing a micro service, to generate interfaces from your own OpenAPI specification custom types, please use

npx openapi-typescript src/interface/api.yaml --output src/interface/openapi.ts

The src/interface/api.yaml should be final OpenAPI specification, not a template one.

openapi -typescript cli is installed in your system as @mojaloop/api-snippets dependency

By convention we are keeping micro service OpenAPI specification in src/interface folder

DTO type aliasing

Type aliasing could be very handy when working with src/interface/openapi.ts file. Suggested pattern is to create a new file src/interface/api.ts and declare aliases inside:

import { components } from './openapi.ts'

// reexport openapi if needed
export * as openapi from './openapi.ts'

// let define some aliases for schemas
export namespace Schemas {
  export type CorrelationId = components['schemas']['CorrelationId']
  export type Money = components['schemas']['Money']
  export type MyCustomRequest = components['schemas']['MyCustomRequest']

So later in you implementation code you can refer to interfaces via these aliases:

import { Schemas } from 'src/interface/api.ts'

let request: Schemas.MyCustomRequest = { ... }

DTO usage examples

please check in src/example.ts for further reading

DTO linting

to lint generated files use:

npm run lint

the npm run build:dto script is already executing linting with auto-fixing

there is pre-commit hook setup witch do a linting for staged files.

DTO testing

  • testing of DTO declarations

Comparing openapi specification - useful commands

For difference:

docker run --rm -t -v $(pwd)/docs:/docs:ro tufin/oasdiff diff /docs/fspiop-rest-v1.1-openapi3-snippets.yaml /docs/fspiop-rest-v2.0-openapi3-snippets.yaml -f text

For changelog:

docker run --rm -t -v $(pwd)/docs:/docs:ro tufin/oasdiff changelog /docs/fspiop-rest-v1.1-openapi3-snippets.yaml /docs/fspiop-rest-v2.0-openapi3-snippets.yaml



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