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"use strict";
Object.defineProperty(exports, "__esModule", {
value: true
});
exports.subscribe = subscribe;
exports.createSourceEventStream = createSourceEventStream;
var _inspect = _interopRequireDefault(require("../jsutils/inspect.js"));
var _isAsyncIterable = _interopRequireDefault(require("../jsutils/isAsyncIterable.js"));
var _Path = require("../jsutils/Path.js");
var _GraphQLError = require("../error/GraphQLError.js");
var _locatedError = require("../error/locatedError.js");
var _values = require("../execution/values.js");
var _execute = require("../execution/execute.js");
var _getOperationRootType = require("../utilities/getOperationRootType.js");
var _mapAsyncIterator = _interopRequireDefault(require("./mapAsyncIterator.js"));
function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
function subscribe(argsOrSchema, document, rootValue, contextValue, variableValues, operationName, fieldResolver, subscribeFieldResolver) {
/* eslint-enable no-redeclare */
// Extract arguments from object args if provided.
return arguments.length === 1 ? subscribeImpl(argsOrSchema) : subscribeImpl({
schema: argsOrSchema,
document: document,
rootValue: rootValue,
contextValue: contextValue,
variableValues: variableValues,
operationName: operationName,
fieldResolver: fieldResolver,
subscribeFieldResolver: subscribeFieldResolver
});
}
/**
* This function checks if the error is a GraphQLError. If it is, report it as
* an ExecutionResult, containing only errors and no data. Otherwise treat the
* error as a system-class error and re-throw it.
*/
function reportGraphQLError(error) {
if (error instanceof _GraphQLError.GraphQLError) {
return {
errors: [error]
};
}
throw error;
}
function subscribeImpl(args) {
var schema = args.schema,
document = args.document,
rootValue = args.rootValue,
contextValue = args.contextValue,
variableValues = args.variableValues,
operationName = args.operationName,
fieldResolver = args.fieldResolver,
subscribeFieldResolver = args.subscribeFieldResolver;
var sourcePromise = createSourceEventStream(schema, document, rootValue, contextValue, variableValues, operationName, subscribeFieldResolver); // For each payload yielded from a subscription, map it over the normal
// GraphQL `execute` function, with `payload` as the rootValue.
// This implements the "MapSourceToResponseEvent" algorithm described in
// the GraphQL specification. The `execute` function provides the
// "ExecuteSubscriptionEvent" algorithm, as it is nearly identical to the
// "ExecuteQuery" algorithm, for which `execute` is also used.
var mapSourceToResponse = function mapSourceToResponse(payload) {
return (0, _execute.execute)({
schema: schema,
document: document,
rootValue: payload,
contextValue: contextValue,
variableValues: variableValues,
operationName: operationName,
fieldResolver: fieldResolver
});
}; // Resolve the Source Stream, then map every source value to a
// ExecutionResult value as described above.
return sourcePromise.then(function (resultOrStream) {
return (// Note: Flow can't refine isAsyncIterable, so explicit casts are used.
(0, _isAsyncIterable.default)(resultOrStream) ? (0, _mapAsyncIterator.default)(resultOrStream, mapSourceToResponse, reportGraphQLError) : resultOrStream
);
});
}
/**
* Implements the "CreateSourceEventStream" algorithm described in the
* GraphQL specification, resolving the subscription source event stream.
*
* Returns a Promise which resolves to either an AsyncIterable (if successful)
* or an ExecutionResult (error). The promise will be rejected if the schema or
* other arguments to this function are invalid, or if the resolved event stream
* is not an async iterable.
*
* If the client-provided arguments to this function do not result in a
* compliant subscription, a GraphQL Response (ExecutionResult) with
* descriptive errors and no data will be returned.
*
* If the the source stream could not be created due to faulty subscription
* resolver logic or underlying systems, the promise will resolve to a single
* ExecutionResult containing `errors` and no `data`.
*
* If the operation succeeded, the promise resolves to the AsyncIterable for the
* event stream returned by the resolver.
*
* A Source Event Stream represents a sequence of events, each of which triggers
* a GraphQL execution for that event.
*
* This may be useful when hosting the stateful subscription service in a
* different process or machine than the stateless GraphQL execution engine,
* or otherwise separating these two steps. For more on this, see the
* "Supporting Subscriptions at Scale" information in the GraphQL specification.
*/
function createSourceEventStream(schema, document, rootValue, contextValue, variableValues, operationName, fieldResolver) {
// If arguments are missing or incorrectly typed, this is an internal
// developer mistake which should throw an early error.
(0, _execute.assertValidExecutionArguments)(schema, document, variableValues);
return new Promise(function (resolve) {
// If a valid context cannot be created due to incorrect arguments,
// this will throw an error.
var exeContext = (0, _execute.buildExecutionContext)(schema, document, rootValue, contextValue, variableValues, operationName, fieldResolver);
resolve( // Return early errors if execution context failed.
Array.isArray(exeContext) ? {
errors: exeContext
} : executeSubscription(exeContext));
}).catch(reportGraphQLError);
}
function executeSubscription(exeContext) {
var schema = exeContext.schema,
operation = exeContext.operation,
variableValues = exeContext.variableValues,
rootValue = exeContext.rootValue;
var type = (0, _getOperationRootType.getOperationRootType)(schema, operation);
var fields = (0, _execute.collectFields)(exeContext, type, operation.selectionSet, Object.create(null), Object.create(null));
var responseNames = Object.keys(fields);
var responseName = responseNames[0];
var fieldNodes = fields[responseName];
var fieldNode = fieldNodes[0];
var fieldName = fieldNode.name.value;
var fieldDef = (0, _execute.getFieldDef)(schema, type, fieldName);
if (!fieldDef) {
throw new _GraphQLError.GraphQLError("The subscription field \"".concat(fieldName, "\" is not defined."), fieldNodes);
}
var path = (0, _Path.addPath)(undefined, responseName, type.name);
var info = (0, _execute.buildResolveInfo)(exeContext, fieldDef, fieldNodes, type, path); // Coerce to Promise for easier error handling and consistent return type.
return new Promise(function (resolveResult) {
var _fieldDef$subscribe;
// Implements the "ResolveFieldEventStream" algorithm from GraphQL specification.
// It differs from "ResolveFieldValue" due to providing a different `resolveFn`.
// Build a JS object of arguments from the field.arguments AST, using the
// variables scope to fulfill any variable references.
var args = (0, _values.getArgumentValues)(fieldDef, fieldNodes[0], variableValues); // The resolve function's optional third argument is a context value that
// is provided to every resolve function within an execution. It is commonly
// used to represent an authenticated user, or request-specific caches.
var contextValue = exeContext.contextValue; // Call the `subscribe()` resolver or the default resolver to produce an
// AsyncIterable yielding raw payloads.
var resolveFn = (_fieldDef$subscribe = fieldDef.subscribe) !== null && _fieldDef$subscribe !== void 0 ? _fieldDef$subscribe : exeContext.fieldResolver;
resolveResult(resolveFn(rootValue, args, contextValue, info));
}).then(function (eventStream) {
if (eventStream instanceof Error) {
throw (0, _locatedError.locatedError)(eventStream, fieldNodes, (0, _Path.pathToArray)(path));
} // Assert field returned an event stream, otherwise yield an error.
if (!(0, _isAsyncIterable.default)(eventStream)) {
throw new Error('Subscription field must return Async Iterable. ' + "Received: ".concat((0, _inspect.default)(eventStream), "."));
}
return eventStream;
}, function (error) {
throw (0, _locatedError.locatedError)(error, fieldNodes, (0, _Path.pathToArray)(path));
});
}
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