Merge pull request #1037 from ministryofjustice/fix/deserializer

fix: Apply transformer to duplicate resources correctly
ministryofjustice · Nov 24, 2020 · c82160f · c82160f
2 parents 6386a96 + fe1b203
commit c82160f
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Showing 2 changed files with 55 additions and 7 deletions.
diff --git a/common/lib/api-client/transformers/transform-resource.js b/common/lib/api-client/transformers/transform-resource.js
@@ -2,17 +2,31 @@ const { cloneDeep } = require('lodash')
 
 module.exports = function transformResource(transformer) {
   return function deserializer(item, included) {
+    if (!transformer) {
+      return this.deserialize.resource.call(this, item, included)
+    }
+
     const _this = cloneDeep(this)
     const modelName = this.pluralize.singular(item.type)
 
+    // Ensure we remove this deserializer to avoid infinite loop
     delete _this.models[modelName].options.deserializer
 
-    const deserialized = _this.deserialize.resource.call(_this, item, included)
+    // call devour deserializer
+    const deserializedData = _this.deserialize.resource.call(
+      _this,
+      item,
+      included
+    )
 
-    if (!transformer) {
-      return deserialized
-    }
+    const transformedData = transformer(deserializedData)
+
+    // we need to clear the cache to avoid the original resource being loaded
+    // the cache is a collection and doesn't allow an item to be updated
+    this.deserialize.cache.clear()
+    // set the new transformed data to the cache for future deserializations
+    this.deserialize.cache.set(item.type, item.id, transformedData)
 
-    return transformer(deserialized)
+    return transformedData
   }
 }
diff --git a/common/lib/api-client/transformers/transform-resource.test.js b/common/lib/api-client/transformers/transform-resource.test.js
@@ -3,8 +3,8 @@ const { cloneDeep } = require('lodash')
 const transformResource = require('./transform-resource')
 
 describe('API Client', function () {
-  describe('Models', function () {
-    describe('#transform', function () {
+  describe('Transformers', function () {
+    describe('#transformResource', function () {
       let output, _this, item, included
 
       beforeEach(function () {
@@ -18,11 +18,16 @@ describe('API Client', function () {
             singular: sinon.stub().returnsArg(0),
           },
           deserialize: {
+            cache: {
+              clear: sinon.stub(),
+              set: sinon.stub().returnsArg(1),
+            },
             resource: sinon.stub().returnsArg(0),
           },
         }
         included = []
         item = {
+          id: '12345',
           type: 'book',
           foo: 'bar',
         }
@@ -35,10 +40,23 @@ describe('API Client', function () {
 
         it('should not transform output', function () {
           expect(output).to.deep.equal({
+            id: '12345',
             type: 'book',
             foo: 'bar',
           })
         })
+
+        it('should call original deserializer', function () {
+          expect(_this.deserialize.resource).to.be.calledOnceWithExactly(
+            item,
+            included
+          )
+        })
+
+        it('should not adjust cache', function () {
+          expect(_this.deserialize.cache.clear).not.to.be.called
+          expect(_this.deserialize.cache.set).not.to.be.called
+        })
       })
 
       context('with transformer', function () {
@@ -61,6 +79,7 @@ describe('API Client', function () {
 
         it('should return transformed resource', function () {
           expect(output).to.deep.equal({
+            id: '12345',
             type: 'book',
             foo: 'bar',
             _fizz: 'buzz',
@@ -69,6 +88,7 @@ describe('API Client', function () {
 
         it('should not mutate original item', function () {
           expect(item).to.deep.equal({
+            id: '12345',
             type: 'book',
             foo: 'bar',
           })
@@ -81,6 +101,20 @@ describe('API Client', function () {
           )
         })
 
+        it('should adjust devour cache', function () {
+          expect(_this.deserialize.cache.clear).to.have.been.calledWithExactly()
+          expect(_this.deserialize.cache.set).to.have.been.calledWithExactly(
+            'book',
+            '12345',
+            {
+              id: '12345',
+              type: 'book',
+              foo: 'bar',
+              _fizz: 'buzz',
+            }
+          )
+        })
+
         it.skip('should delete model deserializer', function () {
           const _that = cloneDeep(_this)
           delete _that.models.book.options.deserializer