Always order collection suggestions alphabetically (#38)

Instead of by count, because the count is always 1 or 2 anyway (depending on whether the backend is listed with 1 or 2 versions). And then the count doesn't need to be displayed anymore either.

The new ordering revealed that there was a collection with id=null and title=null, which I traced back to the old Mundialis backend. It returned an error instead of a valid collections object in its `GET /collections` response. So I introduced a safety check in the pipelines that populate the `collections` and `processes` MongoDB collections.

server.js

@@ -367,7 +367,7 @@ server.get('/api/backends/:backend/*', function(req, res, next) {
 
 // list collections
 server.get('/api/collections', function(req, res, next) {
-    aggregate(dbqueries.GET_DISTINCT_COLLECTIONS_WITH_COUNT_PIPELINE, 'collections')
+    aggregate(dbqueries.GET_DISTINCT_COLLECTIONS_PIPELINE, 'collections')
         .then(prepare)
         .then(data => { res.send(data); next(); })
         .catch(err => next(err));

src/components/DiscoverSection.vue

@@ -28,7 +28,6 @@
 				:multiple="true" :hideSelected="true" :closeOnSelect="false" :preserveSearch="true" openDirection="below">
 				<template slot="option" slot-scope="props" style="width: 100%">
 					<strong>{{props.option.id || '"'+props.search+'"'}}</strong>
-					<span v-if="props.option.count">&nbsp;({{props.option.count}})</span>
 					<p style="margin-bottom:0">{{props.option.title || "&nbsp;"}}</p>
 				</template>	
 			</Multiselect>

src/dbqueries.js

@@ -65,31 +65,30 @@ module.exports = {
         } }
     ],
     GET_ALL_COLLECTIONS_PIPELINE: [
-        { $match: { path: '/collections' } },
+        { $match: { path: '/collections', 'content.collections': {$exists: true} } },
         { $addFields: { 'content.collections.backend': '$backend', 'content.collections.backendTitle': '$backendTitle', 'content.collections.retrieved': '$retrieved', 'content.collections.unsuccessfulCrawls': '$unsuccessfulCrawls' } },
         { $project: { 'collection': '$content.collections' } },
         { $unwind: '$collection' },
         { $replaceRoot: { newRoot: '$collection' } }
     ],
     GET_ALL_PROCESSES_PIPELINE: [
         // basically like for collections
-        { $match: { path: '/processes' } },
+        { $match: { path: '/processes', 'content.processes': {$exists: true} } },
         { $addFields: { 'content.processes.backend': '$backend', 'content.processes.backendTitle': '$backendTitle', 'content.processes.retrieved': '$retrieved', 'content.processes.unsuccessfulCrawls': '$unsuccessfulCrawls' } },
         { $project: { 'process': '$content.processes' } },
         { $unwind: '$process' },
         { $replaceRoot: {newRoot: '$process'} },
         // convert `parameters` object to array because otherwise we can't search for parameter descriptions (MongoDB doesn't support wildcards for object keys)
         { $addFields: { 'parametersAsArray' : { $objectToArray: '$parameters' } } }
     ],
-    GET_DISTINCT_COLLECTIONS_WITH_COUNT_PIPELINE: [
+    GET_DISTINCT_COLLECTIONS_PIPELINE: [
         { $project: {id: {$ifNull: ["$id", "$name"]}, title: 1} },   // allow both id (v0.4) and name (v0.3)
         { $group: {     // group by collection id, at the same time calculate the sum, and maintain title
             _id: {$toLower: "$id"},
             id: {$first: "$id"},
             title: {$first: "$title"},  // if a collection *does* appear twice, the title is usually the same, so just using the first occurrence is enough
-            count: {$sum: 1}
         } },
-        { $sort: {count: -1, id: 1} }  // sort by count DESC, id ASC
+        { $sort: {id: 1} }  // sort by id ASC
     ],
     GET_DISTINCT_PROCESSES_WITH_COUNT_PIPELINE: [
         { $project: {id: {$ifNull: ["$id", "$name"]}, summary: 1} },   // allow both id (v0.4) and name (v0.3)