Add query param to define the number of categories to be ranked

lib/cartodb/backends/dataview.js

@@ -24,7 +24,7 @@ module.exports = DataviewBackend;
 
 DataviewBackend.prototype.getDataview = function (mapConfigProvider, user, params, callback) {
 
-    var dataviewName = params.dataviewName;  
+    var dataviewName = params.dataviewName;
     step(
         function getMapConfig() {
             mapConfigProvider.getMapConfig(this);
@@ -94,7 +94,7 @@ function getQueryRewriteData(mapConfig, dataviewDefinition, params) {
 }
 
 function getOverrideParams(params, ownFilter) {
-    var overrideParams = _.reduce(_.pick(params, 'start', 'end', 'bins', 'offset'),
+    var overrideParams = _.reduce(_.pick(params, 'start', 'end', 'bins', 'offset', 'categories'),
         function castNumbers(overrides, val, k) {
             if (!Number.isFinite(+val)) {
                 throw new Error('Invalid number format for parameter \'' + k + '\'');

lib/cartodb/controllers/layergroup.js

@@ -109,7 +109,8 @@ LayergroupController.prototype.register = function(app) {
         'bins', // number
         'aggregation', //string
         'offset', // number
-        'q' // widgets search
+        'q', // widgets search
+        'categories', // number
     ];
 
     app.get(

lib/cartodb/models/dataview/aggregation.js

@@ -245,6 +245,10 @@ module.exports = class Aggregation extends BaseDataview {
             return null;
         }
 
+        const limit = Number.isFinite(override.categories) && override.categories > 0 ?
+            override.categories :
+            CATEGORIES_LIMIT;
+
         const aggregationSql = aggregationDataviewQueryTpl({
             override: override,
             query: this.query,
@@ -256,7 +260,7 @@ module.exports = class Aggregation extends BaseDataview {
                 aggregationColumn: this.aggregationColumn || 1
             }),
             isFloatColumn: this._isFloatColumn,
-            limit: CATEGORIES_LIMIT
+            limit
         });
 
         debug(aggregationSql);

test/acceptance/dataviews/aggregation.js

@@ -325,7 +325,7 @@ describe('aggregation-dataview: special float values', function() {
     });
 });
 
-describe('categories param', function () {
+describe('aggregation dataview tuned by categories query param', function () {
     afterEach(function(done) {
         if (this.testClient) {
             this.testClient.drain(done);
@@ -388,16 +388,41 @@ describe('categories param', function () {
         ]
     };
 
-    it('should accept cartegories param to customize aggregation dataview', function (done) {
-        this.testClient = new TestClient(mapConfig, 1234);
-        const params = {
-            categories: 2
-        };
+    var scenarios = [
+        {
+            params: { own_filter: 0, categories: -1 },
+            categoriesExpected: 4
+        },
+        {
+            params: { own_filter: 0, categories: 0 },
+            categoriesExpected: 4
+        },
+        {
+            params: { own_filter: 0, categories: 1 },
+            categoriesExpected: 1
+        },
+        {
+            params: { own_filter: 0, categories: 2 },
+            categoriesExpected: 2
+        },
+        {
+            params: { own_filter: 0, categories: 4 },
+            categoriesExpected: 4
+        },
+        {
+            params: { own_filter: 0, categories: 5 },
+            categoriesExpected: 4
+        }
+    ];
 
-        this.testClient.getDataview('categories', params, (err, dataview) => {
-            assert.ifError(err);
-            assert.equal(dataview.categoriesCount, 2);
-            done();
+    scenarios.forEach(function (scenario) {
+        it(`should handle cartegories to customize aggregations: ${JSON.stringify(scenario.params)}`, function (done) {
+            this.testClient = new TestClient(mapConfig, 1234);
+            this.testClient.getDataview('categories', scenario.params, (err, dataview) => {
+                assert.ifError(err);
+                assert.equal(dataview.categories.length, scenario.categoriesExpected);
+                done();
+            });
         });
     });
 });

test/support/test-client.js

@@ -415,7 +415,7 @@ TestClient.prototype.getDataview = function(dataviewName, params, callback) {
                 own_filter: params.hasOwnProperty('own_filter') ? params.own_filter : 1
             };
 
-            ['bbox', 'bins', 'start', 'end', 'aggregation', 'offset'].forEach(function(extraParam) {
+            ['bbox', 'bins', 'start', 'end', 'aggregation', 'offset', 'categories'].forEach(function(extraParam) {
                 if (params.hasOwnProperty(extraParam)) {
                     urlParams[extraParam] = params[extraParam];
                 }