Merge pull request #25 from rynobax/master

Adding conditional (and/or) helpers

Author: thebigredgeek

README.md

@@ -168,6 +168,28 @@ const resolvers = combineResolvers([
 export default resolvers;
 ```
 
+Conditional resovlers:
+```javascript
+import { and, or } from 'apollo-resolvers';
+
+import isFooResolver from './foo';
+import isBarResolver from './bar';
+
+const banResolver = (root, { input }, { models: { UserModel } })=> UserModel.ban(input);
+
+// Will execute banResolver if either isFooResolver or isBarResolver successfully resolve
+// If none of the resolvers succeed, the error from the last conditional resolver will
+// be returned
+const orBanResolver = or(isFooResolver, isBarResolver)(banResolver);
+
+// Will execute banResolver if both isFooResolver and isBarResolver successfully resolve
+// If one of the condition resolvers throws an error, it will stop the execution and
+// return the error
+const andBanResolver = and(isFooResolver, isBarResolver)(banResolver);
+
+// In both cases, conditions are evaluated from left to right
+```
+
 ## Resolver context
 
 Resolvers are provided a mutable context object that is shared between all resolvers for a given request.  A common pattern with GraphQL is inject request-specific model instances into the resolver context for each request.  Models frequently reference one another, and unbinding circular references can be a pain.  `apollo-resolvers` provides a request context factory that allows you to bind context disposal to server responses, calling a `dispose` method on each model instance attached to the context to do any sort of required reference cleanup necessary to avoid memory leaks:

dist/context.js.map

@@ -1 +1,3 @@
 export declare const combineResolvers: (resolvers?: any[]) => any;
+export declare const and: (...conditions: any[]) => (resolver: any) => any;
+export declare const or: (...conditions: any[]) => (resolver: any) => (...query: any[]) => Promise<{}>;

dist/helper.d.ts

@@ -3,3 +3,27 @@ import * as merge from "deepmerge";
 // Helper function to combine multiple resolver definition hashes into a single hash for consumption by Apollostack's graphql-server
 export const combineResolvers = (resolvers = []) => resolvers
   .reduce((combined, resolver) => merge(combined, resolver));
+
+// Accepts multiple authentication resolvers and returns a function which will be called
+// if all of the authentication resolvers succeed, or throw an error if one of them fails
+export const and = (...conditions) => resolver => {
+  return conditions.reduceRight((p, c) => {
+    return c.createResolver(p);
+  }, resolver)
+}
+
+// Accepts multiple authentication resolvers and returns a function which will be called
+// if any of the authentication resolvers succeed, or throw an error if all of them fail
+export const or = (...conditions) => resolver => (...query) => {
+  return new Promise((resolve, reject) => {
+    let limit = conditions.length - 1;
+    const attempt = (i) =>
+      conditions[i].createResolver(resolver)(...query)
+        .then(res => resolve(res))
+        .catch(err => {
+          if(i === limit) reject(err);
+          else attempt(i + 1);
+        });
+    attempt(0);
+  });
+}

dist/helper.js

@@ -1,8 +1,10 @@
 import { expect } from 'chai';
+import { stub } from 'sinon';
 
 import {
-  combineResolvers
+  combineResolvers, and, or,
 } from '../../dist/helper';
+import { createResolver } from '../../dist/resolver';
 
 describe('(unit) src/helper.js', () => {
   describe('combineResolvers', () => {
@@ -51,4 +53,125 @@ describe('(unit) src/helper.js', () => {
       });
     })
   });
+
+  describe('Conditional resolvers', () => {
+    const conditionalErr = new Error('conditional error');
+    const successResolver = createResolver(() => null, () => null);
+    const failureResolver = createResolver(() => { throw conditionalErr; }, () => null);
+
+    describe('and', () => {
+      it('(true, true) succeeds', () => {
+        const resolver = and(successResolver, successResolver)(() => true);
+        return resolver().then(res => expect(res).to.be.true);
+      });
+
+      it('(false, true) throws', () => {
+        const resolver = and(failureResolver, successResolver)(() => true);
+        return resolver().catch(err => expect(err).to.equal(conditionalErr));
+      });
+
+      it('(false, false) throws', () => {
+        const resolver = and(failureResolver, failureResolver)(() => true);
+        return resolver().catch(err => expect(err).to.equal(conditionalErr));
+      });
+
+      it('stops evaluating resolvers after first failure', () => {
+        const r1 = {
+          handle: () => { throw conditionalErr },
+          error: () => null,
+        };
+
+        const r2 = {
+          handle: () => null,
+          error: () => null,
+        };
+
+        stub(r1, 'handle', r1.handle);
+        stub(r2, 'handle', r2.handle);
+
+        const resolver = or(
+          createResolver(r1.handle, r1.error),
+          createResolver(r2.handle, r2.error)
+        )(() => true);
+        return resolver().catch(err => {
+          expect(err).to.equal(conditionalErr)
+          expect(r1.handle.calledOnce).to.be.true;
+          expect(r2.handle.notCalled).to.be.true;
+        });
+      });
+
+      it('only calls the result resolver once', () => {
+        const r1 = {
+          handle: () => true,
+          error: () => null,
+        };
+
+        stub(r1, 'handle', r1.handle);
+
+        const resolver = and(successResolver, successResolver)(createResolver(r1.handle, r1.error));
+        return resolver().then(res => {
+          expect(res).to.be.true;
+          expect(r1.handle.calledOnce).to.be.true;
+        });
+      });
+    });
+
+    describe('or', () => {
+      it('(true, true) succeeds', () => {
+        const resolver = or(successResolver, successResolver)(() => true);
+        return resolver().then(res => expect(res).to.be.true);
+      });
+
+      it('(false, true) succeeds', () => {
+        const resolver = or(failureResolver, successResolver)(() => true);
+        return resolver().then(res => expect(res).to.be.true);
+      });
+
+      it('(false, false) throws', () => {
+        const resolver = or(failureResolver, failureResolver)(() => true);
+        return resolver().catch(err => expect(err).to.equal(conditionalErr));
+      });
+
+      it('stops evaluating resolvers after first success', () => {
+        const r1 = {
+          handle: () => null,
+          error: () => null,
+        };
+
+        const r2 = {
+          handle: () => null,
+          error: () => null,
+        };
+
+        stub(r1, 'handle', r1.handle);
+        stub(r2, 'handle', r2.handle);
+
+        const resolver = or(
+          createResolver(r1.handle, r1.error),
+          createResolver(r2.handle, r2.error)
+        )(() => true);
+        return resolver().then(res => {
+          expect(res).to.be.true;
+          expect(r1.handle.calledOnce).to.be.true;
+          expect(r2.handle.notCalled).to.be.true;
+        });
+      });
+
+      it('only calls the result resolver once', () => {
+        const r1 = {
+          handle: () => true,
+          error: () => null,
+        };
+
+        stub(r1, 'handle', r1.handle);
+
+        const resolver = or(failureResolver, successResolver)(createResolver(r1.handle, r1.error));
+        return resolver().then(res => {
+          expect(res).to.be.true;
+          expect(r1.handle.calledOnce).to.be.true;
+        });
+      });
+    });
+
+  });
 });