search-string-for-google-drive/index.js

helper function to create query string for drive.files.list when using Google Drive API v3

/*
 * search-string-for-google-drive -- creates search string for Drive API v3 drive.files.list "q" parameter
 * This is a helper function for creating the "q" query string described in https://developers.google.com/drive/v3/web/search-parameters
 *
 *  Copyright 2017-2018 Paul Brewer, Economic and Financial Technology Consulting LLC <drpaulbrewer@eaftc.com>
 *  This file is open source software.  License: The MIT License
 *
 */

"use strict";

const folderMimeType = 'application/vnd.google-apps.folder';

function escape(s) {
  return "'" + String(s).replace(/'/g, "\\'") + "'";
}

// used capital Q here to avoid confusion with search string q defined later

const Q = {
  "string": function(op, combiner) {
    return function(k, v) {
      if (Array.isArray(v)) {
        return '( ' +
          v.map(function(eachv) {
            return (k + ' ' + op + ' ' + escape(eachv));
          }).join(' ' + combiner + ' ') +
          ' )';
      }
      return k + ' ' + op + ' ' + escape(v);
    };
  },

  "boolean": function() {
    return function(k, v) {
      if ((typeof(v) === 'string') && (v.charAt(0) === "F" || v.charAt(0) === "f" || v === "0"))
        v = false;
      return k + ' = ' + (!!v);
    };
  },

  "collection": function(combiner) {
    return function(k, v) {
      if (Array.isArray(v)) {
        return '( ' +
          v.map(function(eachv) {
            return escape(eachv) + ' in ' + k;
          }).join(' ' + combiner + ' ') +
          ' )';
      }
      return escape(v) + ' in ' + k;
    };
  },

  "hash": function() {
    return function(k, v) {
      return Object.keys(v).map(
        function(hk) {
          return k + ' has { key=' + escape(hk) + ' and value=' + escape(v[hk]) + ' }';
        }).join(' and ');
    };
  },

  "isFolder": function() {
    return function(k, v) {
      if ((typeof(v) === 'string') && (v.charAt(0) === "F" || v.charAt(0) === "f" || v === "0"))
        v = false;
      const sep = (v) ? ' = ' : ' != ';
      return 'mimeType' + sep + escape(folderMimeType);
    };
  }
};

const handlers = {
  name: Q.string('=', 'or'),
  fullText: Q.string('contains', 'and'),
  mimeType: Q.string('=', 'or'),
  trashed: Q.boolean(),
  starred: Q.boolean(),
  parents: Q.collection('or'),
  owners: Q.collection('or'),
  writers: Q.collection('or'),
  readers: Q.collection('or'),
  sharedWithMe: Q.boolean(),
  properties: Q.hash('and'),
  appProperties: Q.hash('and'),
  visibility: Q.string('=', 'or'),
  isFolder: Q.isFolder()
};


function ssgd(spec, matchAll) {
  const queries = (
    Object.keys(spec)
    .filter(function(k) {
      return (spec[k] !== undefined) && (spec[k] !== null);
    })
    .map(function(k) {
      if (typeof(handlers[k]) === 'function')
        return (handlers[k])(k, spec[k]);
      // fix singular<-->plural
      const lastChar = k.charAt(k.length - 1);
      const kPlural = (lastChar !== 's') ? k + 's' : false;
      const kSingular = (lastChar === 's') ? k.substr(0, k.length - 1) : false;
      if (kPlural && (typeof(handlers[kPlural]) === 'function'))
        return (handlers[kPlural])(kPlural, spec[k]);
      if (kSingular && (typeof(handlers[kSingular]) === 'function'))
        return (handlers[kSingular])(kSingular, spec[k]);
      throw new Error("search key " + escape(k) + " unsupported");
    })
  );
  const q = queries.join(' and ');
  if ((q.length === 0) && (matchAll))
    return q;
  if (q.length > 0)
    return q;
  throw new Error("blank, match-all, query prohibited by configuration at search-string-for-google-drive");
}

ssgd.supported = function() {
  return Object.keys(handlers);
};

// someobj.hasOwnProperty(prop) is replaced with
// Object.prototype.hasOwnProperty.call(someobj,prop)
// see https://eslint.org/docs/rules/no-prototype-builtins

ssgd.isSupported = function(k) {
  return (k in handlers) && (Object.prototype.hasOwnProperty.call(handlers,k));
};

ssgd.extract = function(slop) {
  const spec = {};
  Object.keys(handlers).forEach(function(k) {
    if ((k in slop) && (Object.prototype.hasOwnProperty.call(slop,k))) {
      spec[k] = slop[k];
    }
  });
  return spec;
};

module.exports = ssgd;