Driver MongoLab

This is the the driver for DB.MONGOLAB described in Database abstraction with google apps script
The library reference is

MPAHw_-cHNDxsYAg263J7Fai_d-phDA33

Background to implementation.

MongoLab offers a number of plans for cloud based MongoDB. I discovered they have a .5gb Free Sandbox plan, so I thought I’d give it a go. They recommend using their supplied libraries, but of course there is not one for Google Apps Script, so I used their REST API access to implement enough capabilities to cover all the features of Database abstraction with google apps script. Of course, MongoDB has zillions of other features that I don’t use, but in this mode it’s a great substitute for ScriptDB and alternative to Parse.com – and the performance is excellent

Authentication

It’s simple – just an API key you can get from your MongoLab dashboard

Getting started

  • Sign up with MongoLab
  • Create a hosting plan
  • Create a database
  • Store your API key in your script Properties.

Getting a handle

Like all other drivers it all starts with getting a handle.  In this case, the MongoDB collection is ‘customers’, and the database I created is called ‘xliberation’. The property is the one you stored your API key against, and should like this
{“restAPIKey”:”your api key”}

 var userStore = PropertiesService.getScriptProperties();

  var handler = new cDataHandler.DataHandler (
      'customers',                        
      cDataHandler.dhConstants.DB.MONGOLAB,      
      undefined,
      'xliberation',
      JSON.parse(userStore.getProperty("mongoLabKeys")) );
     
  if(!handler.isHappy()) {
    throw ( 'unable to get mongolab handler');
  }

The example above uses the cDataHandler. Nowadays it’s better to use the cDbAbstraction interface. An example is shown in the slides below. 

Now you’re good to go. The syntax is the same for all back ends. See Some test cases for various backends for examples of various syntaxes, and see Comparing all back ends performance for how MongoLab performs. It’s superfast as a scriptDB replacement.

The Code

/** wrapper
 */
function createDriver (handler,siloId,driverSpecific,driverOb, accessToken) {
    return new DriverMongoLab(handler,siloId,driverSpecific,driverOb, accessToken);
}

function getLibraryInfo () {
  return {
    info: {
      name:'cDriverMongoLab',
      version:'2.2.0',
      key:'MPAHw_-cHNDxsYAg263J7Fai_d-phDA33',
      description:'mongolab driver for dbabstraction',
      share:'https://script.google.com/d/11N6camwOikILS28dwqvIlv44D1y0JMCTL9IeeUKkDV1amGvjWIeg-KbH/edit?usp=sharing'
    },
    dependencies:[
    ]
  }; 
}

/**
 * DriverMongoLab
 * @param {cDataHandler} handler the datahandler thats calling me
 * @param {string} collection the name of the mongodb collection
 * @param {string} database the mongo database
 * @param {object} database the mongo credential object
 * @return {object} result with handle or some error
 */ 
var DriverMongoLab = function (handler,collection,database,credentials) {
  var siloId = collection;
  var self = this;
  var uniqueKey = database;
  var parentHandler = handler;
  var enums = parentHandler.getEnums();
  var keyOb = credentials;
  var handleError, handleCode;
  var DRIVERFIELDS = ['_id'];
  
  // im not able to do transactions
  self.transactionCapable = false;
  
  // i  need transaction locking
  self.lockingBypass = false;
  
  // i am aware of transactions and know about the locking i should do
  self.transactionAware = true;
  
  self.getDbId = function () {
    return uniqueKey;
  };
  
  // create connection to mongo
  self.createHandle = function() {
    return uniqueKey;
  }

  var handle = self.createHandle();

  self.getVersion = function () {
    var v = getLibraryInfo().info;
    return v.name + ':' + v.version;
  };
  
  self.getDriveHandle =  function () {
    return handle;
  };
  
  self.getType = function () {
    return enums.DB.MONGOLAB;
  };
  
  /**
   * DriverMongoLab.getTableName()
   * @return {string} table name or silo
   */
  self.getTableName = function () {
    return siloId;
  };

  self.getEndPoint = function (optExtras) {
    extras = optExtras ? "/" + optExtras : "";
    return  "https://api.mongolab.com/api/1/databases/" + self.getDbId() + "/collections/" + self.getTableName() + extras + "?apiKey=" + keyOb.restAPIKey;
  };
  
/** create the urlfetch options 
 * @param {object} options any additional options to add
 * @return {object} the urlfetch options
 */
  self.getOptions = function (options) {
    var options = options || {};
    options.contentType = "application/json" ;
    options.muteHttpExceptions = true;
    return options;
  }
  
  self.execute = function (url,options) {
    handleCode = enums.CODE.OK;
    handleError ="";
    
    var result = parentHandler.rateLimitExpBackoff ( function () {

      var h = UrlFetchApp.fetch(url,options);

      if (h.getResponseCode() !== 201 && h.getResponseCode() !== 200 && h.getResponseCode() !== 204) {
        handleCode = enums.CODE.HTTP;
        handleError = h.getContentText() +"(http error code:" + h.getResponseCode()+ ")(url:" +url+")";
      }
      var t = h.getContentText();

      if (t) {
        var o = JSON.parse(t);

        if (o && o.message) {
          handleCode = enums.CODE.DRIVER;
          handleError = JSON.stringify(o.message);
          return null;
        }
        else { 
          return o;
        }
      }
      else {
        return h.getResponseCode();
      }

    });

    return result;
  }
  
  
  /**
   * DriverMongoLab.save()
   * @param {Array.object} obs array of objects to write
   * @return {object} results from selected handler
   */
   
   self.save = function (obs) {

    // save it after adding my own id fields
    var obd = obs.map(function(d) { 
      var o = parentHandler.clone(d);
      o._id = parentHandler.generateUniqueString() ; 
      return o; 
    });
    
    // lock the entire transaction
    var result =  parentHandler.writeGuts ( 'save', function () {
      return self.execute (self.getEndPoint() , self.getOptions ({
        method: "POST",
        payload: JSON.stringify(obd)
      }));
    // the result property of the lock protect is the result of the function that was protected
   });
   return parentHandler.makeResults ( handleCode, handleError, obs , null , obd.map(function(d) { 
     return getMixedId_(d);
   }));
       
  };

  /**
   * DriverMongoLab.removeByIds()
   * @param {array.string} keys  list of keys to delete
   * @return {object} results from selected handler
   */   
  self.removeByIds = function (keys) {

    var options = self.getOptions({
      method: "DELETE"
    });
    
    var r = parentHandler.writeGuts ( 'removeByIds', function () {    
      var dr = keys.map( function (d) {
        return self.execute (self.getEndPoint(d) , options);
      });
      return dr;
    });
    
   r.keys = keys;
   return r;
    
  };

  /**
   * DriverMongoLab.remove()
   * @param {object} queryOb some query object 
   * @param {object} queryParams additional query parameters (if available)
   * @param {Array.object} optReplaceWith adding this makes it a replace
   * @return {object} results from selected handler
   */   
  self.remove = function (queryOb,queryParams,optReplaceWith) {

    var obs = optReplaceWith || [];
    var params = parentHandler.getQueryParams(parentHandler.clone(queryParams));
    handleCode = params.handleCode;
    handleError = params.handleError;
    
    // lock the entire transaction
    if (handleCode === enums.CODE.OK) {
      var useParams = parentHandler.makeUseParams(params.data);
      var options = self.getOptions({
        method: "PUT",
        payload: JSON.stringify(obs)
      });
        
      var result =  parentHandler.writeGuts ( 'remove', function () {
        return self.execute (self.getEndPoint() + makeQueryString_(queryOb) + makeParamString_(useParams) , options);
      });
    }
    return parentHandler.makeResults (  handleCode, handleError, result);
  };
   /**
   * DriverMongoLab.count()
   * @param {object} queryOb some query object 
   * @param {object} queryParams additional query parameters (if available)
   * @return {object} results from selected handler
   */
   
  self.count = function (queryOb,queryParams) {
  
    var params = parentHandler.getQueryParams(parentHandler.clone(queryParams)), result;
    handleCode = params.handleCode;
    handleError = params.handleError;

    if (handleCode === enums.CODE.OK) {
      var useParams = parentHandler.makeUseParams(params.data);
      try {
        var r = parentHandler.readGuts ( 'count', function () {
          return self.execute (self.getEndPoint() + makeQueryString_(queryOb) + makeParamString_(useParams) + "&c=true" , 
            self.getOptions({
              method: "GET",
            }));
        });
        result = [{count:r}];
      }
      catch(err) {
        handleError = JSON.stringify(err);
        handleCode =  enums.CODE.DRIVER;
      }
    }
    return parentHandler.makeResults (  handleCode, handleError, result);
  };

//-------------------------- 
   /**
   * DriverMongoLab.query()
   * @param {object} queryOb some query object 
   * @param {object} queryParams additional query parameters (if available)
   * @param {boolean} keepIds whether or not to keep driver specifc ids in the results
   * @return {object} results from selected handler
   */
  self.query = function (queryOb,queryParams,keepIds,optFlatten) {
  
    // take a copy of params so as not to disturb what's passed
    var exhausted = false;
    var driverIds = [], handleKeys = [];
    
    var queryString = makeQueryString_(queryOb,optFlatten);
    var params = parentHandler.getQueryParams(parentHandler.clone(queryParams));
    handleCode = params.handleCode;
    handleError = params.handleError;
    
    try {
      if (handleCode === enums.CODE.OK) {
        
        var result = parentHandler.readGuts ( 'query', function () {
          // this is chunking to get over limits
          var useParams = parentHandler.makeUseParams(params.data);
          
          var skip = useParams.skip.skip ,  limit = useParams.limit.limit ,exhausted = false;
          var result = [];
          
          while (handleCode === enums.CODE.OK &amp;&amp; (result.length < limit || limit ===0) &amp;&amp; !exhausted) {
            
            useParams.skip.skip = skip + result.length;
            var paramString = makeParamString_(useParams);
            
            var w = self.execute ( 
              self.getEndPoint() + queryString + paramString , self.getOptions ({
              method: "GET"
              }));
            
            exhausted = !w || (w.length === 0 );
            
            if (handleCode === enums.CODE.OK &amp;&amp; !exhausted) {
              
              w.forEach (function(d) {
                if( result.length < limit || limit ===0) {
                  var o ={};
                  driverId ={};
                  for (var k in d) {
                    if (DRIVERFIELDS.indexOf(k) === -1) {
                      o[k] = d[k];
                    }
                    else {
                      driverId[k] = d[k];
                    }
                  }
                  handleKeys.push(getMixedId_ (d) );
                  driverIds.push(driverId);
                  result.push(o);
                }
              });
            }
          }
          return result;
        });
      }
    }
    catch(err) {
      handleError = err;
      handleCode =  enums.CODE.DRIVER;
    }
    
    return parentHandler.makeResults (handleCode,handleError,result,keepIds ? driverIds :null,keepIds ? handleKeys:null);
  };
  function getMixedId_ (ob) {
    return parentHandler.isObject(ob._id) ? ob._id["$oid"] : ob._id; 
  }
  function makeParamString_(ps) {

      // fix with mongo api equivalents
    p='';
    
    if (ps.sort) {
      p+= '&amp;s=' + encodeURIComponent('{"' + ps.sort.sortKey + '":' + (ps.sort.sortDescending ?  -1:1) +'}'); 
    }
    if (ps.limit) {
        p+= '&amp;l=' + ps.limit.limit;
    }
    if (ps.skip) {
        p+= '&amp;sk=' + ps.skip.skip;
    }
    
    return p;
  }

  function makeQueryString_(queryOb, optFlatten) {
  
    // special case - we dont flatten $or
    var flatten = typeof optFlatten === 'undefined' ? true: optFlatten;
    var q='';
    if (queryOb) {
      var qb = flatten ? parentHandler.flatten(queryOb,true) : queryOb;

      var qob = Object.keys(qb).reduce(function(p,c) {
        if  (qb.hasOwnProperty (enums.SETTINGS.CONSTRAINT)) {
          p = qb[enums.SETTINGS.CONSTRAINT].reduce( function (a,b) {
            a[b.constraint] = b.value; 
            return a;
          },{});
        }
        else {
          p=qb;
        }
        return p;
      },{});
      return '&amp;q=' + encodeURIComponent(JSON.stringify(qob));
    }
    else {
      return '';
    }

  };
  
    
  /**
   * Driver.get()
   * @param {Array.string} keys the unique return in handleKeys for this object
   * @return {object} results from selected handler
   */


  self.get = function (keys) {
   
   // this kind of sucks, since we have to to a separate update for each key

   if(!Array.isArray(keys)) keys = [keys];

   handleCode=enums.CODE.OK;
   handleError='';
   var result;
   try {
     result = parentHandler.readGuts ( 'get', function () {
      return keys.map (function(d) {
        var k = parentHandler.isObject(d) ? d.key : d;
        var r = self.execute (self.getEndPoint(k)  , self.getOptions({
          method: "GET"
        }));
        if (!r || r.length === 0) handleCode = enums.CODE.NOMATCH;
        return r;
      });
     });
    }
    catch(err) {
      handleError = err;
      handleCode =  enums.CODE.DRIVER;
    }

    return self.splitKeys(parentHandler.makeResults (handleCode,handleError,result));
  };
  
  /**
   * DriverSheet.splitKeys()
   * take a result and remove special fields and move handlekeys
   * @param {object} qResult standard result
   * @return {object} modified standard result
   */
  self.splitKeys = function (qResult) {
    
    if (qResult.handleCode >=0) {
      var s = parentHandler.dropFields ( DRIVERFIELDS , '_id' , qResult.data);
      qResult.data = s.obs;
      qResult.handleKeys = s.keys;
    }
    
    return qResult;
  };

  /**
   * Driver.update()
   * @param {Array.string} keys the unique return in handleKeys for this object
   * @param {object} obs what to update it to
   * @return {object} results from selected handler
   */
  self.update = function (keys,obs) {
   
   // this kind of sucks, since we have to to a separate update for each key

   if(!Array.isArray(keys)) keys = [keys];
   if(!Array.isArray(obs)) obs = [obs];
   
   if(keys.length !== obs.length &amp;&amp; obs.length !== 1)  {
     return parentHandler.makeResults (enums.CODE.KEYS_AND_OBJECTS,'objects- ' + obs.length + ' keys- ' + keys.length,result);
   }
   
   
   handleCode=enums.CODE.OK;
   handleError='';
   var result;
   try {
      result = parentHandler.writeGuts ( 'update', function () { 
        return keys.map (function(d,i) {
          var r = self.execute (self.getEndPoint(d)  , self.getOptions({
            method: "PUT",
            payload: JSON.stringify(obs.length === 1 ? obs[0] : obs[i])
          }));
          if (!r || r.length === 0) handleCode = enums.CODE.NOMATCH;
          return r;
        });
      });
    }
    catch(err) {
      handleError = err;
      handleCode =  enums.CODE.DRIVER;
    }

    return parentHandler.makeResults (handleCode,handleError,result);
  };
  
  return self;
  
}

Here’s some libraries you’ll need or are used internally

librarykeycomments
cDataHandlerMj61W-201_t_zC9fJg1IzYiz3TLx7pV4jAbstracted interface to back end databases, and all known drivers
cCacheHandlerM3reA5eBxtwxSqCEgPywb9ai_d-phDA33Manages caching of query results
cNamedLockMpv7vUR0126U53sfSMXsAPai_d-phDA33Cross script locking of abstract resources
cFlattenMqxKdBrlw18FDd-X5zQLd7yz3TLx7pV4jFlattens complex objects to 1 level dot syntax objects  so they can be stored/queries in a 2 dimensional space

See more like this in Database abstraction with google apps script