Make populate param multilevel

src/index.js

@@ -146,11 +146,39 @@ const getProjection = projection => {
   return fields;
 };
 
-const getPopulation = population =>
-  population.split(',').map(path => {
-    return { path };
+const getPopulation = population => {
+  const cache = {};
+
+  function iterateLevels(levels, prevLevels = []) {
+    let populate;
+    let path;
+    const topLevel = levels.shift();
+    prevLevels.push(topLevel);
+
+    const cacheKey = prevLevels.join('.');
+    if (cache[cacheKey]) {
+      path = cache[cacheKey];
+    } else {
+      path = { path: topLevel };
+    }
+    cache[cacheKey] = path;
+
+    if (levels.length) {
+      populate = iterateLevels(levels, prevLevels);
+      if (populate) {
+        path.populate = populate;
+      }
+    }
+    return path;
+  }
+
+  const populations = population.split(',').map(path => {
+    return iterateLevels(path.split('.'));
   });
 
+  return [...new Set(populations)]; // Deduplicate array
+};
+
 const getSort = sort => parseUnaries(sort);
 
 const getSkip = skip => Number(skip);
@@ -213,24 +241,30 @@ const getFilter = (filter, params, options) => {
 };
 
 const mergeProjectionAndPopulation = result => {
-  if (result.projection && result.population) {
-    // Loop the population rows
-    result.population.forEach(row => {
-      const prefix = `${row.path}.`;
+  function iteratePopulation(population, prevPrefix = '') {
+    population.forEach(row => {
+      const prefix = `${prevPrefix}${row.path}.`;
       Object.keys(result.projection).forEach(key => {
-        // If field start with the name of the path, we add it to the `select` property
         if (key.startsWith(prefix)) {
           const unprefixedKey = key.replace(prefix, '');
-          row.select = {
-            ...row.select,
-            [unprefixedKey]: result.projection[key],
-          };
-          // Remove field with . from the projection
-          delete result.projection[key];
+          if (unprefixedKey.indexOf('.') === -1) {
+            row.select = {
+              ...row.select,
+              [unprefixedKey]: result.projection[key],
+            };
+            delete result.projection[key];
+          }
         }
       });
+      if (row.populate) {
+        iteratePopulation([row.populate], prefix);
+      }
     });
   }
+
+  if (result.projection && result.population) {
+    iteratePopulation(result.population);
+  }
 };
 
 const operators = [

test/index.js

@@ -349,21 +349,77 @@ test('populate', t => {
   t.deepEqual(res.population, [{ path: 'a' }, { path: 'b' }, { path: 'c' }]);
 });
 
-test('populate and projection', t => {
-  const res = aqp('populate=a,b,c&fields=j,k,l,a.x,a.y,a.z,b.x,b.y,foo.bar');
+test('populate (nested)', t => {
+  const res = aqp('populate=a,b.b1,c.c1.c2');
   t.truthy(res);
-  t.deepEqual(res.projection, { j: 1, k: 1, l: 1, 'foo.bar': 1 });
   t.deepEqual(res.population, [
     {
       path: 'a',
-      select: { x: 1, y: 1, z: 1 },
+    },
+    {
+      path: 'b',
+      populate: {
+        path: 'b1',
+      },
+    },
+    {
+      path: 'c',
+      populate: {
+        path: 'c1',
+        populate: {
+          path: 'c2',
+        },
+      },
+    },
+  ]);
+});
+
+test('populate (nested, no duplicated)', t => {
+  const res = aqp('populate=a,a.a1,a.a1.a2');
+  t.truthy(res);
+  t.deepEqual(res.population, [
+    {
+      path: 'a',
+      populate: {
+        path: 'a1',
+        populate: {
+          path: 'a2',
+        },
+      },
+    },
+  ]);
+});
+
+test('populate (nested) and projection', t => {
+  const res = aqp(
+    'populate=a,b.b1,c.c1.c2&fields=j,k,foo.bar,a.x,b.x,b.y,b.b1.x,c.x,c.c1.x,c.c1.c2.x,c.c1.c2.y'
+  );
+  t.truthy(res);
+  t.deepEqual(res.projection, { j: 1, k: 1, 'foo.bar': 1 });
+  t.deepEqual(res.population, [
+    {
+      path: 'a',
+      select: { x: 1 },
     },
     {
       path: 'b',
       select: { x: 1, y: 1 },
+      populate: {
+        path: 'b1',
+        select: { x: 1 },
+      },
     },
     {
       path: 'c',
+      select: { x: 1 },
+      populate: {
+        path: 'c1',
+        select: { x: 1 },
+        populate: {
+          path: 'c2',
+          select: { x: 1, y: 1 },
+        },
+      },
     },
   ]);
 });