Machine-readable custom errors for Apollostack's GraphQL server
npm install apollo-errors
  
Install the package:
``bash`
npm install apollo-errors
Create some errors:
`javascript
import { createError } from 'apollo-errors';
export const FooError = createError('FooError', {
message: 'A foo error has occurred'
});
`
Hook up formatting:
`javascript
import express from 'express';
import bodyParser from 'body-parser';
import { formatError } from 'apollo-errors';
import { graphqlExpress } from 'apollo-server-express';
import schema from './schema';
const app = express();
app.use('/graphql',
bodyParser.json(),
graphqlExpress({
formatError,
schema
})
);
app.listen(8080)
`
Throw some errors:
`javascript
import { FooError } from './errors';
const resolverThatThrowsError = (root, params, context) => {
throw new FooError({
data: {
something: 'important'
},
internalData: {
error: The SQL server died.
}
});
}
Witness glorious simplicity:
POST /graphql (200)
`json`
{
"data": {},
"errors": [
{
"message":"A foo error has occurred",
"name":"FooError",
"time_thrown":"2016-11-11T00:40:50.954Z",
"data":{
"something": "important"
}
}
]
}
The internalData property is meant for data you want to store on the error object (e.g. for logging), but not send out to your end users.
You can utilize this data for logging purposes.
`js
import { isInstance as isApolloErrorInstance, formatError as formatApolloError } from 'apollo-errors';
function formatError(error) {
const { originialError } = error;
if (isApolloErrorInstance(originalError)) {
// log internalData to stdout but not include it in the formattedError
console.log(JSON.stringify({
type: error,
data: originalError.data,
internalData: originalError.internalData
}));
}
return formatApolloError(error)
}
`
Creates a new ApolloError object. Note that ApolloError in this context referscreateError
to an error class created and returned by documented below. Error can betime_thrown
initialized with a custom ISODate (default is current ISODate), data object (which will be merged with data specified through createError, if it exists), internalData object (which will be merged with internalData specified trough createError) and message (which will override the message specified through createError).
Creates and returns an error class with the given name and message, optionally initialized with the given data, internalData and options. data and internalData passed to createError will later be merged with any data passed to the constructor.
#### Options (default):
- showPath (false): Preserve the GraphQLError path data.showLocations
- (false): Preserve the GraphQLError locations` data.
Otherwise, if strict is not truthy, returns the original error passed into formatError.
Otherwise, if strict is truthy, returns null.