graphql_mutations.js

const express = require('express');
const graphql = require('express-graphql');
const graphqlTools = require('graphql-tools');

const app = express();

// Sample Data
const blogsData = [{_id: 1, title: 'Hello', content: 'World'}];

// Simple Blog schema with ID, Title and Content fields
const typeDefs = `
    type Blog{
        _id: Int,
        title: String!,
        content: String!
    }

    type Query{
        blogs: [Blog],
        blog(_id: Int): Blog
    }

    input BlogEntry{
        title: String!,
        content: String!
    }

    type Mutation{
        createBlog(input: BlogEntry): Blog!,
        updateBlog(_id: Int, input: BlogEntry): Blog!,
        deleteBlog(_id: Int): Blog!
    }
`;

// Resolver to match the GraphQL query and return data
const resolvers = {
    Query: {
        blogs(root, args, context, info) {
            return blogsData
        },
        blog(root, {_id}, context, info){
            return blogsData.find((b) => b._id == _id);
        }
    },
    Mutation: {
        createBlog(root, {input}, context, info){
            const newBlog = {_id: blogsData.length+1, title: input.title, content: input.content};
            blogsData.push(newBlog);
            return newBlog;
        },

        updateBlog(root, {_id, input}, context, info){
            const blog = blogsData.find((b) => b._id == _id);
            blog.title = input.title;
            blog.content = input.content;
            return blog;
        },

        deleteBlog(root, {_id}, context, info){
            const blogIndex = blogsData.findIndex((b) => b._id == _id);
            const blog = blogsData[blogIndex];
            blogsData.splice(blogIndex, 1);
            return blog;
        }
    }
};

// Build the schema with Type Definitions and Resolvers
const schema = graphqlTools.makeExecutableSchema({typeDefs, resolvers});

app.use('/graphiql', graphql({
    graphiql: true,
    schema
}));

app.listen(3000)