Allow date and term calculation in liquid (#6)

* added moment library

* allow date and term calculation in liquid

* refactor addDuration and subtractDates

* return values directly

* Fix duration in days calculation

* add tests

* Maintain consistency in naming decorators

* use existing decorators to calculate date term calculation

* spell check

* remove functions that are not needed

* WIP: tests updated

* Co-authored-by: Madhav Bhagat <madhav89@gmail.com> tests for add duration and subrtract date

* return duration instead of no of days

* add default argument for getObjectValues function

* handle from_date greater than to_date case

* update tests for negative value of durationInDays

* support for adding durartion and tests for the same

* added tests for assign

* throw error if either value or type is incorrcect in duration calculation.

Co-authored-by: Sumanth Subbarao <sumanth@Sumanths-MacBook-Pro.local>

filters.js

@@ -1,6 +1,7 @@
 const strftime = require("./src/util/strftime.js");
 const _ = require("./src/util/underscore.js");
 const isTruthy = require("./src/syntax.js").isTruthy;
+const moment = require("moment");
 
 var escapeMap = {
   "&": "&",
@@ -9,6 +10,7 @@ var escapeMap = {
   '"': """,
   "'": "'"
 };
+
 var unescapeMap = {
   "&": "&",
   "&lt;": "<",
@@ -39,7 +41,6 @@ var filters = {
   divided_by: (v, arg) => divide(v, arg),
   downcase: v => v.toLowerCase(),
   escape: escape,
-
   escape_once: str => escape(unescape(str)),
   first: v => v[0],
   floor: v => Math.floor(v),
@@ -146,15 +147,41 @@ function filterNumericKeysFromObject(obj) {
   return Object.keys(obj).filter(key => !Number.isNaN(parseInt(obj[key])));
 }
 
-function getObjectValues(obj) {
+function getObjectValues(obj = {}) {
   let resultObj = {};
   keys = Object.keys(obj);
   keys.forEach(key => {
     resultObj[key] = obj[key];
   });
   return resultObj;
 }
-
+function calculateDurationInDays(fromDate, toDate) {
+  const durationInMilliSeconds = toDate.getTime() - fromDate.getTime();
+  const durationInDays = durationInMilliSeconds/(1000*3600*24);
+  if(durationInDays < 0) {
+    throw new Error("toDate should be greater than fromDate");
+  }
+  return {
+    type: "days",
+    value: durationInDays
+  }
+}
+function addDuration(v, arg) {
+  const v_days = computeDaysFromUnit(v.value, v.type);
+  const arg_days = computeDaysFromUnit(arg.value, arg.type);
+  const total_days = v_days + arg_days;
+  return {
+    type: "days",
+    value: total_days
+  }
+}
+function checkIfDurationObjects(v, arg) {
+  const units = ['days', 'weeks', 'months', 'years'];
+  if(units.indexOf(v.type) != -1 && units.indexOf(arg.type) != -1) {
+    return true;
+  }
+  return false;
+}
 function subtract(v, arg) {
   return performOperations(v, arg, "SUBTRACT");
 }
@@ -167,8 +194,26 @@ function add(v, arg) {
   return performOperations(v, arg, "ADD");
 }
 
+
 function performOperations(v, arg, operation) {
+  if(Object.prototype.toString.call(v) === '[object Date]' && Object.prototype.toString.call(arg) === '[object Date]') {
+    return operationOnDate(v, arg, operation);
+  }
+  if (Object.prototype.toString.call(v) === '[object Date]' && typeof arg === "object") {
+    const addType = ['days', 'weeks', 'months', 'years'];
+    const {value, type} = arg;
+    if (value && addType.indexOf(type) != -1) {
+      return operationOnDate(v, arg, operation);
+    }else {
+      throw new Error("value or type is incorrect.")
+    }
+  } 
   if (typeof v === "object" && typeof arg === "object") {
+    const isDurationObjects = checkIfDurationObjects(v, arg)
+    if(isDurationObjects) {
+      const result = addDuration(v, arg);
+      return result;
+    }
     result = Object.assign(getObjectValues(arg), getObjectValues(v));
     const numberKeysOfArg = filterNumericKeysFromObject(arg);
     const numberKeysOfV = filterNumericKeysFromObject(v);
@@ -182,24 +227,28 @@ function performOperations(v, arg, operation) {
       return result;
     } else {
       console.warn("The objects don't have any common numeric attributes");
+      return;
     }
-  } else if (typeof v === "number" && typeof arg === "object") {
+  } 
+  if (typeof v === "number" && typeof arg === "object") {
     result = getObjectValues(arg);
     const numberKeys = filterNumericKeysFromObject(arg);
     numberKeys.forEach(key => {
       result[key] = operationOnItem(v, arg[key], operation);
     });
     return result;
-  } else if (typeof v === "object" && typeof arg === "number") {
+  } 
+  if (typeof v === "object" && typeof arg === "number") {
     result = getObjectValues(v);
     const numberKeys = filterNumericKeysFromObject(v);
     numberKeys.forEach(key => {
       result[key] = operationOnItem(v[key], arg, operation);
     });
     return result;
-  } else {
-    return operationOnItem(v, arg, operation);
-  }
+  } 
+
+  return operationOnItem(v, arg, operation);
+
 }
 
 function operationOnItem(v, arg, operation) {
@@ -215,5 +264,32 @@ function operationOnItem(v, arg, operation) {
   }
 }
 
+function operationOnDate(v, arg, operation) {
+  switch(operation) {
+    case "ADD":
+      return new Date(moment(v).add(arg.value, arg.type));
+    case "SUBTRACT":
+      return calculateDurationInDays(v, arg);
+    default:
+      throw new Error(`${operation}, not supported`)
+  }
+}
+
+function computeDaysFromUnit(value, type) {
+  switch(type) {
+    case "days":
+      return value;
+    case "weeks":
+      return value * 7;
+    case "months":
+      return value * 30;
+    case "years":
+      return value * 365;
+    default:
+      return 0;
+  }
+}
+
+
 registerAll.filters = filters;
 module.exports = registerAll;

package.json

@@ -35,6 +35,7 @@
   "homepage": "https://github.com/harttle/liquidjs#readme",
   "dependencies": {
     "any-promise": "^1.3.0",
+    "moment": "^2.24.0",
     "resolve-url": "^0.2.1"
   },
   "browser": {

test/filters.js

@@ -3,6 +3,8 @@ const chaiAsPromised = require('chai-as-promised')
 const expect = chai.expect
 var liquid = require('..')()
 chai.use(chaiAsPromised)
+const moment = require("moment");
+
 
 var ctx = {
   date: new Date(),
@@ -16,7 +18,15 @@ var ctx = {
     category: 'foo'
   }, {
     category: 'bar'
-  }]
+  }],
+
+  duration_10_weeks: {value: 10, type: "weeks"},
+  duration_20_days: {value: 20, type: "days"},
+  duration_2_months: {value: 2, type: "months"},
+  duration_3_years: {value: 3, type: "years"},
+
+  from_date: new Date("March 17, 2020"),
+  to_date: new Date("March 17, 2022")
 }
 
 function test (src, dst) {
@@ -184,6 +194,14 @@ describe('filters', function () {
       () => test('{{ 183.357 | minus: 12 }}', '171.357'))
     it('should convert first arg as number', () => test('{{ "4" | minus: 1 }}', '3'))
     it('should convert both args as number', () => test('{{ "4" | minus: "1" }}', '3'))
+    it('should return {"type":"days","value":730}', () => {
+      try {
+        const dst = {type: "days", value: 730};
+        return test('{% assign duration = from_date | minus: to_date %}{{duration}}', JSON.stringify(dst))
+      } catch(e) {
+        console.error(e.message)
+      }
+    })
   })
 
   describe('modulo', function () {
@@ -213,6 +231,30 @@ describe('filters', function () {
       () => test('{{ 183.357 | plus: 12 }}', '195.357'))
     it('should convert first arg as number', () => test('{{ "4" | plus: 2 }}', '6'))
     it('should convert both args as number', () => test('{{ "4" | plus: "2" }}', '6'))
+    it('should add 10 weeks to current date', () => {
+      const dst = new Date(moment(ctx.date).add(10, "weeks")).toDateString()
+      return test('{% assign term = date | plus: duration_10_weeks | date: "%a %b %d %Y" %}{{ term }}', dst)
+    })
+    it('should add 20 days to current date', () => {
+      const dst = new Date(moment(new Date()).add(20, "days")).toDateString()
+      return test('{% assign term = date | plus: duration_20_days | date: "%a %b %d %Y"%}{{ term }}', dst)
+    })
+    it('should add 2 months to current date', () => {
+      const dst = new Date(moment(new Date()).add(2, "months")).toDateString()
+      return test('{% assign term = date | plus: duration_2_months | date: "%a %b %d %Y"%}{{ term }}', dst)
+    })
+    it('should add 3 years to current date', () => {
+      const dst = new Date(moment(new Date()).add(3, "years")).toDateString()
+      return test('{{ date | plus: duration_3_years | date: "%a %b %d %Y"}}', dst)
+    })
+    it('should return {type: "days", value: 80};', () => {
+      const dst = {type: "days", value: 80};
+      return test('{{ duration_20_days | plus: duration_2_months }}', JSON.stringify(dst))
+    })
+    it('should return {type: "days", value: 130};', () => {
+      const dst = {type: "days", value: 130};
+      return test('{{ duration_10_weeks | plus: duration_2_months }}', JSON.stringify(dst))
+    })
   })
 
   it('should support prepend', function () {