Stitcher

This project is here to learn and showcase HotChocolate schema stitching capabilities. It operates entirely in-memory as persistence mechanisms are already a well-known problem.

This example project is a conceptual cafe. It has a menu (products), a list of customers and a list of sales. Each of these sections is a separate GraphQL schema (and application). The schemas are stitched together into a single schema.

Running the project

Run all the downstream services first, and then followed by the stitcher (Gateway).

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Experiment results:

Type Stitching:

We able to achieve type stitching by using the @delegate directive. This needs to be defined in the Stitching.graphql file in the Sticher App.

In this example, there is type stitching available on the Transactions type. We are stitching both the customer, and product types onto the transaction type.

To see this, execute the following queries against the Stitcher App:

mutation AddCustomer {
    addCustomer(firstName: "John", lastName: "Smith") {
        customerId
    }
}

mutation PurchaseItem {
    purchaseItem(customerId: 2, productId: 2, amount: 5.0) {
        id
        customerId
        transactionType
    }
}

query GetCustomerTransactions {
    transactionsForCustomer(customerId: 2) {
        id,
        transactionType,
        transactionDate,
        amount,
        product {
            productId
            name
        }
        customer {
            customerId
            firstName
            lastName
        }
    }
}