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This blog post is part of a series. You must finish part-1, part-2, part-3 & part-4 before continuing here.
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Adding a list of companies

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Our schema has an idea about the presence of a user. Next, we will introduce the idea of a company and relate it to a user.

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Every company will have an id, name and description. And we will associate a company with a particular user by adding a companyId property to the user object.

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First off, we will create a list of two companies in the db.json file and add a companyId property to the individual users. Then we will go to our schema.js file and define a CompanyType.

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server/db.json
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{\n  "users": [\n    {\n      "id": "45",\n      "firstName": "Nicole",\n      "age": 25,\n      "companyId": "1"\n    },\n    {\n      "id": "26",\n      "firstName": "Alex",\n      "age": 24,\n      "companyId": "1"\n    },\n    {\n      "id": "28",\n      "firstName": "Harry",\n      "age": 27,\n      "companyId": "2"\n    },\n  ],\n  "companies": [\n    {\n      "id": "1",\n      "name": "SendGrid",\n      "description": "Email"\n    },\n    {\n      "id": "2",\n      "name": "HP",\n      "description": "Computer"\n    }\n  ]\n}
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Now if we visit the JSON server at http://localhost:3000/companies, we get the list of companies that we have defined inside the db.json file.

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Now, let's understand the process that GraphQL went through to fetch the user(id:45) and the company associated with the user.

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When we made the query, it went to RootQuery with an args object with an id property of 45. The RootQuery then pointed GraphQL to the user with an id of 45, thanks to the resolve() function.

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We also wanted to know about the company associated with that user. This time the user’s resolve() function got called, with the first argument of parentValue and an empty args object. (The parentValue is the node on the graph the query is coming from, which is user 45 in our case.) The args object didn't get passed along the chain and the resolve() function of the UserType object returned a Promise that eventually returned to us the company we were looking for.

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So, a better way to thing about schema is to think of them as a bunch of functions that return references to other objects in our graph and we can think of the edges in the graph as resolve() functions.

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Go to part-6

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