fastify-openapi-glue/docs/operationResolver.md

generate a fastify configuration from an openapi specification

<h1 align="center">fastify-openapi-glue</h1>

## operationResolver
The easiest way to use `fastify-openapi-glue` is to use the [serviceHandlers](serviceHandlers.md) option.

However if you need more flexibility in mapping operationId's to methods then the `operationResolver` can be convenient.

You provide a function and that function returns the method that will handle the request.

An example of a simple resolver is:
```javascript
const myObject = { getPetbyId: async () => { pet: "Doggie the dog" }};

function (operationId) {
  if (operationId in myObject) {
    return myObject[operationId];
  }
};
```
But you can make the logic as complex as you like. 

In this example `myObject[operationId]` points to a function, but you can also point it to a full Fastify route definition, e.g.:
```javascript
const myObject = { getPetbyId: {
    onSend: async (req, res) => {
      res.code(304);
      return null;
    },
    handler: async () => {
      return { pet: "Doggie the dog" };
    },
  };
}
```
In that case any properties returned by the operationResolver are added to the route configuration that the plugin already created itself, overriding any already existing properties.

The operationResolver will only be called during the creation of the Fastify configuration.