About MERN details

1. COURSE NAME: MERN STACK WEB
DEVELOPMENT(MSWD)
COURSE CODE: 22SDCS01R
TOPIC: GRAPHQL, APOLLOSERVER, APOLLO STUDIO EXPLORER,
PARAMETERS RESOLVER, MUTATIONS
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2. GRAPHQL
GraphQL is a query language. It provides a query in the form of a string
thatis sent to a server. The server interprets the query and then returns the
result in the form of JSON format to the client.
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3. ADVANTAGES OF GRAPHQL
• GraphQL is faster
• Best for complex systems and microservices
• No over-fetching and under-fetching problems
• Hierarchical Structure
• Defines a data shape
• Code-sharing
• Strongly typed
• Protocol, not a storage
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4. DISADVANTAGES OF GRAPHQL
• GraphQL Query Complexity
• GraphQL Caching
• GraphQL Rate Limiting
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7. STEPS FOR GRAPHQL QUERY
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10. THE SCHEMA DEFINITION LANGUAGE (SDL)
type Person {
name: String!
age: Int!
}
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11. APOLLOSERVER
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13. APOLLO STUDIO EXPLORER
• Type this into URL http://localhost:4000/ then it is redirected to
open into apollo server studio explorer
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15. PARAMETERS RESOLVER
A resolver is a function that's responsible for populating the data
for a single field in your schema. It can populate that data in any
way you define, such as by fetching data from a back-end
database or a third-party API.
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16. type Query {
reviews: [Review]
review(id: ID!): Review
games: [Game]
authors: [Author]
}`
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const resolvers = {
Query: {
games() {
return db.games
},
authors() {
return db.authors
},
reviews() {
return db.reviews
},
review(_, args) {
return db.reviews. find((review) => review.id === args.id)
}
}

17. IN APOLLO STUDIO EXPLORER
query ReviewQuery($id: ID!) {
review(id: $id) {
rating,
content
}
}
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19. THANK YOU
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