Ghost/core/frontend/helpers/match.js
Hannah Wolfe 981f11da95
Added basic {{match}} helper
refs: https://github.com/TryGhost/Team/issues/759

- The match helper allows for basic equals and not equals comparisons,
Example:
  {{match title "=" "Getting Started"}}
  {{match slug "!=" "welcome"}}
- There's a lot more functionality we want to add here, so that it ends up being a replacement for {{#has}}
- However, this first iteration is already useful, especially in the context of custom theme settings
- Therefore we are adding it early, and will document it along with custom theme settings when that goes GA very soon
2021-10-14 19:36:56 +01:00

104 lines
3.0 KiB
JavaScript

const {SafeString} = require('../services/rendering');
const logging = require('@tryghost/logging');
const tpl = require('@tryghost/tpl');
const _ = require('lodash');
const messages = {
invalidAttribute: 'Invalid or no attribute given to match helper'
};
/**
* This is identical to the built-in if helper, except inverse/fn calls are replaced with false/true
* https://github.com/handlebars-lang/handlebars.js/blob/19bdace85a8d0bc5ed3a4dec4071cb08c8d003f2/lib/handlebars/helpers/if.js#L9-L20
*/
function isEmptyValue(value) {
if (!value && value !== 0) {
return true;
} else if (Array.isArray(value) && value.length === 0) {
return true;
} else {
return false;
}
}
const handleConditional = (conditional, options) => {
if (_.isFunction(conditional)) {
conditional = conditional.call(this);
}
// Default behavior is to render the positive path if the value is truthy and not empty.
// The `includeZero` option may be set to treat the condtional as purely not empty based on the
// behavior of isEmpty. Effectively this determines if 0 is handled by the positive path or negative.
if ((!options.hash.includeZero && !conditional) || isEmptyValue(conditional)) {
return false;
} else {
return true;
}
};
const handleMatch = (data, operator, value) => {
let result;
switch (operator) {
case '!=':
result = data !== value;
break;
default:
result = data === value;
}
return result;
};
module.exports = function match(...attrs) {
// options = options || {};
// options.hash = options.hash || {};
// options.data = options.data || {};
const options = attrs.pop();
const isBlock = _.has(options, 'fn');
let result;
if (_.isEmpty(attrs)) {
logging.warn(tpl(messages.invalidAttribute));
return;
}
// If any of the attributes are safe strings, change them back to their original value
attrs = attrs.map((attr) => {
if (attr instanceof SafeString) {
return attr.string;
}
return attr;
});
if (attrs.length === 1) {
// CASE: single attribute, treat it as simple true/false (like the if helper)
result = handleConditional(attrs[0], options);
} else if (attrs.length === 2) {
// CASE: two attributes, assume the operator is "="
result = handleMatch(attrs[0], '=', attrs[1]);
} else if (attrs.length === 3) {
// CASE: three attributes, handle the match exactly
result = handleMatch(attrs[0], attrs[1], attrs[2]);
} else {
logging.warn(tpl(messages.invalidAttribute));
return;
}
// If we're in block mode, return the outcome from the fn/inverse functions
if (isBlock) {
if (result) {
return options.fn(this);
}
return options.inverse(this);
}
// Else return the result as a SafeString Eg.{string: false} || {string: true}
return new SafeString(result);
};