Initial commit

Author: pqvst

generator.js

@@ -0,0 +1,51 @@
+const moment = require("moment-timezone");
+const _ = require("lodash");
+
+
+module.exports = function (start, end, timezone) {
+
+    // get range as moments
+    start = moment(start);
+    end = moment(end);
+
+
+    // get zone information
+    const zone = moment.tz.zone(timezone);
+
+
+    // find timezone offset boundaries for the specified range
+    const boundaries = [];
+    _.each(zone.untils, (until, i) => {
+        const offset = zone.offsets[i];
+        if (until > start.valueOf()) {
+            boundaries.push({ until, offset });
+            if (until > end.valueOf()) {
+                return false;
+            }
+        }
+    });
+
+
+    // recursively build condition structure
+    function getCondition(boundaries) {
+        const boundary = boundaries.shift();
+        const until = boundary.until;
+        const offset = boundary.offset * 60 * 1000; // minutes -> milliseconds
+
+        if (boundaries.length == 0) {
+            return { $subtract: ["$time", offset] };
+        }
+
+        return {
+            $cond: {
+                if: { $lt: ["$time", new Date(until)] },
+                then: { $subtract: ["$time", offset] },
+                else: getCondition(boundaries)
+            }
+        }
+    }
+
+
+    return getCondition(boundaries);
+};
+

package.json

@@ -0,0 +1,18 @@
+{
+  "name": "tzoffset",
+  "version": "1.0.0",
+  "description": "",
+  "main": "test.js",
+  "scripts": {
+    "start": "node ./test.js"
+  },
+  "author": "",
+  "license": "ISC",
+  "dependencies": {
+    "async": "^2.0.1",
+    "lodash": "^4.15.0",
+    "moment": "^2.14.1",
+    "moment-timezone": "^0.5.5",
+    "mongodb": "^2.2.9"
+  }
+}

test.js

@@ -0,0 +1,84 @@
+const async = require("async");
+const moment = require("moment");
+const mongo = require("mongodb");
+const client = mongo.MongoClient;
+
+const generator = require("./generator");
+const DB_URL = "mongodb://<username>:<password>@<hostname>:<port>/<database>";
+const DB_COLLECTION = "tzoffset_test";
+
+
+let db, res;
+async.waterfall([
+
+    // connect to database
+    function (done) {
+        client.connect(DB_URL, (err, _db) => {
+            db = _db;
+            done(err);
+        });
+    },
+
+    //------------------------------------------------------
+    // drop test collection
+    //function (done) {
+    //    db.collection(DB_COLLECTION).drop((err) => {
+    //        done(err);
+    //    });
+    //},
+    //------------------------------------------------------
+
+    //------------------------------------------------------
+    // insert test documents
+    //function (done) {
+    //    const docs = [
+    //        { time: new Date("2016-03-27T00:59:59Z"), name: "CET" },
+    //        { time: new Date("2016-03-27T01:00:00Z"), name: "CEST" },
+    //        { time: new Date("2016-03-27T01:00:01Z"), name: "CEST" },
+    //        { time: new Date("2016-10-30T00:59:59Z"), name: "CEST" },
+    //        { time: new Date("2016-10-30T01:00:00Z"), name: "CET" },
+    //        { time: new Date("2016-10-30T01:00:01Z"), name: "CET" }
+    //    ];
+    //    db.collection(DB_COLLECTION).insert(docs, (err, res) => {
+    //        done(err);
+    //    })
+    //},
+    //------------------------------------------------------
+
+    // perform test query
+    function (done) {
+        const start = moment.utc("2016-01-01T00:00:00Z");
+        const end = moment.utc("2017-01-01T00:00:00Z");
+        const tz = "Europe/Berlin";
+
+        const cond = generator(start, end, tz);
+        db.collection(DB_COLLECTION).aggregate([
+            {
+                $project: {
+                    name: "$name",
+                    time_orig: "$time",
+                    time_conv: cond
+                }
+            },
+            {
+                $limit: 100
+            }
+        ]).toArray((err, _res) => {
+            res = _res;
+            done(err);
+        });
+    }
+
+], (err) => {
+
+    if (err) {
+        console.error(err);
+    } else {
+        console.log(res);
+    }
+
+    if (db) {
+        db.close();
+    }
+
+});