expose the printf function in handlebars

informatics-isi-edu · Mar 29, 2024 · 47d10f6 · 47d10f6
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diff --git a/docs/user-docs/handlebars.md b/docs/user-docs/handlebars.md
@@ -24,6 +24,7 @@ This document summarizes the key concepts of Handlebars that are relevant to Der
   - [$location](#location)
   - [$session](#session)
 - [Helpers](#helpers)
+  - [printf helper](#printf-helper)
   - [formatDate helper](#formatdate-helper)
   - [humanizeBytes helper](#humanizebytes-helper)
   - [Math Helpers](#math-helpers)
@@ -485,9 +486,27 @@ A Handlebars helper call is a simple identifier, followed by zero or more parame
 {{HELPER_NAME PARAM1 PARAM2 }}
 ```
 
+### printf helper
+
+You can use the `printf` helper to format a value. The expected format follows the same syntax as [PreFormat](pre-format.md#syntax).
+
+Syntax:
+```
+{{printf value format }}
+```
+
+Example:
+```
+{{printf 3.1415 "%.1f" }} ==> "3.1"
+
+{{printf 43 "%4d" }} ==> "  43"
+```
+
+Keep in mind that `printf` doesn't check the validity of the given values. So for example if the value might not be a number, you cannot blindly use the `d` type and should guard against it.
+
 ### formatDate helper
 
-You can use the `formatDate` helper to take any `date` or `timestamp[tz]` value and format it according to the [Pre Format Guide](pre-format.md#syntax-for-dates-and-timestamps).
+You can use the `formatDate` helper to take any `date`, `timestamp`, or `timestamptz` value and format it according to the [Pre Format Guide](pre-format.md#syntax-for-dates-and-timestamps).
 
 Syntax:
 ```

diff --git a/js/utils/constants.js b/js/utils/constants.js
@@ -227,7 +227,7 @@
         "eq", "ne", "lt", "gt", "lte", "gte", "and", "or", "not", "ifCond",
         "escape", "encode", "formatDate", "encodeFacet",
         "regexMatch", "regexFindFirst", "regexFindAll",
-        "jsonStringify", "toTitleCase", "replace", "humanizeBytes",
+        "jsonStringify", "toTitleCase", "replace", "humanizeBytes", 'printf',
         // math helpers
         "add", "subtract"
     ];

diff --git a/js/utils/handlebar_helpers.js b/js/utils/handlebar_helpers.js
@@ -71,6 +71,13 @@
                 return module.encodeFacetString(options);
             },
 
+            /**
+             * {{printf value "%4d" }}
+             */
+            printf: function (value, format) {
+                return module._printf({ format: format }, value);
+            },
+
             /**
              * {{formatDate value format}}
              *

diff --git a/test/specs/print_utils/tests/01.print_utils.js b/test/specs/print_utils/tests/01.print_utils.js
@@ -36,7 +36,7 @@ exports.execute = function (options) {
             var printInteger = formatUtils.printInteger;
             expect(printInteger(null)).toBe('');
             expect(printInteger(12341234)).toBe('12,341,234');
-            expect(printInteger(0001)).toBe('1');
+            expect(printInteger('0001')).toBe('1');
             expect(printInteger(233)).toBe('233');
             expect(printInteger(23.)).toBe('23');
             expect(printInteger(23.000000000)).toBe('23');
@@ -600,6 +600,12 @@ exports.execute = function (options) {
                 expect(module.renderHandlebarsTemplate("{{formatDate date 'YYYY'}}", {date: null})).toBe("");
             });
 
+            it('printf helper', function () {
+                const render = (t, v) => module.renderHandlebarsTemplate(t, v);
+                expect(render('{{printf 3.1415 "%.1f" }}', {})).toBe('3.1');
+                expect(render('{{printf num "%4d" }}', { num: 43 })).toBe('  43');
+            });
+
             it('humanizeByte helper', function () {
                 // test overloading
                 expect(module.renderHandlebarsTemplate('{{humanizeBytes data }}', {data: 12345678})).toBe('12.3 MB');