Extract fetch-by-page from BPE to service

app/assets/javascripts/admin/services/bulk_products.js.coffee

@@ -1,4 +1,4 @@
-angular.module("ofn.admin").factory "BulkProducts", (dataFetcher) ->
+angular.module("ofn.admin").factory "BulkProducts", (PagedFetcher, dataFetcher) ->
   new class BulkProducts
     products: []
 
@@ -6,13 +6,9 @@ angular.module("ofn.admin").factory "BulkProducts", (dataFetcher) ->
       queryString = filters.reduce (qs,f) ->
         return qs + "q[#{f.property.db_column}_#{f.predicate.predicate}]=#{f.value};"
       , ""
-      return dataFetcher("/api/products/bulk_products?page=1;per_page=20;#{queryString}").then (data) =>
-        @addProducts data.products
 
-        if data.pages > 1
-          for page in [2..data.pages]
-            dataFetcher("/api/products/bulk_products?page=#{page};per_page=20;#{queryString}").then (data) =>
-              @addProducts data.products
+      url = "/api/products/bulk_products?page=::page::;per_page=20;#{queryString}"
+      PagedFetcher.fetch url, (data) => @addProducts data.products
 
     cloneProduct: (product) ->
       dataFetcher("/admin/products/" + product.permalink_live + "/clone.json").then (data) =>

app/assets/javascripts/admin/services/paged_fetcher.js.coffee

@@ -0,0 +1,16 @@
+angular.module("ofn.admin").factory "PagedFetcher", (dataFetcher) ->
+  new class PagedFetcher
+    # Given a URL like http://example.com/foo?page=::page::&per_page=20
+    # And the response includes an attribute pages with the number of pages to fetch
+    # Fetch each page async, and call the processData callback with the resulting data
+    fetch: (url, processData) ->
+      dataFetcher(@urlForPage(url, 1)).then (data) =>
+        processData data
+
+        if data.pages > 1
+          for page in [2..data.pages]
+            dataFetcher(@urlForPage(url, page)).then (data) ->
+              processData data
+
+    urlForPage: (url, page) ->
+      url.replace("::page::", page)

spec/javascripts/unit/admin/services/paged_fetcher.js.coffee

@@ -0,0 +1,13 @@
+describe "PagedFetcher service", ->
+  PagedFetcher = null
+
+  beforeEach ->
+    module "ofn.admin"
+
+  beforeEach inject (_PagedFetcher_) ->
+    PagedFetcher = _PagedFetcher_
+
+  describe "substituting a page in the URL", ->
+    it "replaces ::page:: with the given page number", ->
+      expect(PagedFetcher.urlForPage("http://example.com/foo?page=::page::&per_page=20", 12)).
+        toEqual "http://example.com/foo?page=12&per_page=20"