Structure

The backend is written in TypeScript and runs GraphQL server that talks to neo4j database.

In the setup stage, the backend takes a .csv file(s) and mapping each data row to an edge connecting two nodes. After setup and build, the system allows the user to query the dataset through GraphQL queries.

Libraries

  • apollo-server-express: Runs the GraphQL server, http server, parsing responses to GraphQL queries, validates inputs against GraphQL schema, etc'.

  • compression: Returns GZIP compressed responses to client.

  • cors: Defines cors policy.

  • csvtojson: Convert CSV file to json object in the seeding process.

  • dotenv: Environment variables management.

  • graphql: Official graphql library.

  • neo4j-driver: Official neo4j driver.

  • node-cache: In-memory cache storing frequently queries results.

  • winston: Logger.

Folder Structure

core/
├── LICENSE
├── README.md
├── build
├── logs
├── node_modules
├── nodemon.json
├── now.json
├── package-lock.json
├── package.json
├── setup
│   ├── createSchema.js
│   ├── createTypes.js
│   └── fieldsMapping.js
├── src
│   ├── consts.ts
│   ├── fieldsMapping.ts
│   ├── graphql-resolvers.ts
│   ├── index.ts
│   ├── neo4j.ts
│   ├── seed.ts
│   └── types.ts
├── tests
│   └── neo4j-tests.js
└── tsconfig.json

  • setup: Contains the all needed files for the initial setup of the system. The files in this folder will be described in detail in the Setup page.

  • src: Contains the source files to be compiled to TypeScript.

  • consts.ts: Contains constants and project settings like PROJECT_STAGE etc'.

  • index.ts: The entry point to the project. Runs the GraphQL server and listens for incoming requests.

  • neo4j.ts: A wrapper of neo4j driver implementing CRUD functions and query functions. Implements DBManager class.

  • graphql-resolvers.ts: The GraphQL resolvers which defines execution path for each query or mutation. It corresponds the graphql.schema created in setup stage.

  • fieldsMapping.ts, types.ts: Dynamically created files on the setup stage. More detailed information will be on the "Setup" documentation page.

  • seed.ts: A script using to seed the database, more details explanation will be on the "Seed" documentation page.

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