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var _ = require('lodash');
// This middleware component trims the results array by granularity when
// FallbackQuery was used. FallbackQuery is used for inputs like
// `1090 N Charlotte St, Lancaster, PA` where the address may not exist and
// we must fall back to trying `Lancaster, PA`. If the address does exist then
// FallbackQuery will return results for:
// - address+city+state
// - city+state
// - state
//
// Because the address matched, we're not interested in city+state or state, so
// this component removes results that aren't the most granular.
// layers in increasing order of granularity
var layers = [
'venue',
'address',
'neighbourhood',
'borough',
'locality',
'county',
'region',
'country'
];
// this helper method returns `true` if every result has a matched_query
// starting with `fallback.`
function isFallbackQuery(results) {
return results.every(function(result) {
return result.hasOwnProperty('_matched_queries') &&
!_.isEmpty(result._matched_queries) &&
_.startsWith(result._matched_queries[0], 'fallback.');
});
}
function hasRecordsAtLayers(results, layer) {
return results.some(function(result) {
return result._matched_queries[0] === 'fallback.' + layer;
});
}
function retainRecordsAtLayers(results, layer) {
return results.filter(function(result) {
return result._matched_queries[0] === 'fallback.' + layer;
});
}
function setup() {
return function trim(req, res, next) {
// don't do anything if there are no results or there are non-fallback.* named queries
// there should never be a mixture of fallback.* and non-fallback.* named queries
if (_.isUndefined(res.data) || !isFallbackQuery(res.data)) {
return next();
}
// start at the most granular possible layer. if there are results at a layer
// then remove everything not at that layer.
layers.forEach(function(layer) {
if (hasRecordsAtLayers(res.data, layer )) {
res.data = retainRecordsAtLayers(res.data, layer);
}
});
next();
};
}
module.exports = setup;