mysql - Counting associated entries with Sequelize -

i have 2 tables, locations , sensors. each entry in sensors has foreign key pointing locations. using sequelize, how entries locations , total count of entries in sensors associated each entry in locations?

raw sql:

select      `locations`.*,     count(`sensors`.`id`) `sensorcount`  `locations`  join `sensors` on `sensors`.`location`=`locations`.`id`; group `locations`.`id`; 

models:

module.exports = function(sequelize, datatypes) {     var location = sequelize.define("location", {         id: {             type: datatypes.integer.unsigned,             primarykey: true         },         name: datatypes.string(255)     }, {         classmethods: {             associate: function(models) {                 location.hasmany(models.sensor, {                     foreignkey: "location"                 });             }         }     });      return location; };   module.exports = function(sequelize, datatypes) {     var sensor = sequelize.define("sensor", {         id: {             type: datatypes.integer.unsigned,             primarykey: true         },         name: datatypes.string(255),         type: {             type: datatypes.integer.unsigned,             references: {                 model: "sensor_types",                 key: "id"             }         },         location: {             type: datatypes.integer.unsigned,             references: {                 model: "locations",                 key: "id"             }         }     }, {         classmethods: {             associate: function(models) {                 sensor.belongsto(models.location, {                     foreignkey: "location"                 });                  sensor.belongsto(models.sensortype, {                      foreignkey: "type"                 });             }         }     });      return sensor; }; 

use findall() include() , sequelize.fn() count:

location.findall({     attributes: {          include: [[sequelize.fn("count", sequelize.col("sensors.id")), "sensorcount"]]      },     include: [{         model: sensor, attributes: []     }] }); 

or, may need add group well:

location.findall({     attributes: {          include: [[sequelize.fn("count", sequelize.col("sensors.id")), "sensorcount"]]      },     include: [{         model: sensor, attributes: []     }],     group: ['location.id'] })