Alright so I have a project in NodeJS where I'm utilizing Sequelize for a MySQL ORM. The thing works fantastically however I'm trying to figure out if there is a way to specify what fields are being returned on a query basis or if there's even a way just to do a .query() somewhere.
For example in our user database there can be ridiculous amounts of records and columns. In this case I need to return three columns only so it would be faster to get just those columns. However, Sequelize just queries the table for everything "*" to fulfill the full object model as much as possible. This is the functionality I'd like to bypass in this particular area of the application.
You have to specify the attributes as a property in the object that you pass to findAll():
Project.findAll({attributes: ['name', 'age']}).on('success', function (projects) {
console.log(projects);
});
How I found this:
The query is first called here: https://github.com/sdepold/sequelize/blob/master/lib/model-definition.js#L131
Then gets constructed here: https://github.com/sdepold/sequelize/blob/master/lib/connectors/mysql/query-generator.js#L56-59
Try this in new version
template.findAll({
where: {
user_id: req.params.user_id
},
attributes: ['id', 'template_name'],
}).then(function (list) {
res.status(200).json(list);
})
Use the arrays in the attribute key. You can do nested arrays for aliases.
Project.findAll({
attributes: ['id', ['name', 'project_name']],
where: {id: req.params.id}
})
.then(function(projects) {
res.json(projects);
})
Will yield:
SELECT id, name AS project_name FROM projects WHERE id = ...;
All Answers are correct but we can also use include and exclude as well
Model.findAll({
attributes: { include: ['id'] }
});
Model.findAll({
attributes: { exclude: ['createdAt'] }
});
Source
Related
I have a sequelize model called staff. One of the staff columns is called locations which holds the id's of all the locations this staff is available at. I want to create a query that uses a Location ID to get all staff active at that location. How can I do that using the ORM?
Assuming I have understood your question correctly and your locations column contains CSV data, then you need to use FIND_IN_SET() -
Staff.findAll({
where: sequelize.where(sequelize.fn('FIND_IN_SET', locationId, sequelize.col('locations')), {[Op.gt]: 0})
})
A better option would be to normalize your data as this query is non-SARGable.
In Sequelize, you can perform a query to filter staff based on their locations using the include and where options in your query.
const staff = await Staff.findAll({
include: [
{
model: Location,
as: 'locations',
where: { id: locationId },
through: { attributes: [] }
}
]
});
const findStaff = await StaffModel.findAll({
where: {
locationId: "your locationId"
}
})
I have the following scenario, my application has two entities: box and items with N to N relationship. I am using sequelize with MySQL.
I am using pseudocode to represent the tables:
Box {
id: Integer primary key
name: String
}
Item {
id: Integer primary key
name: String
}
I have set up the schemas with relations hasMany in both directions using the following through relation:
Box.hasMany(Item, { through: Box_Item });
Item.hasMany(Box, { through: Box_Item });
Box_Item {
id_box: Integer,
id_item: Integer,
item_order: Integer
}
With primary_key(id_box, id_item).
I tested it and I can call myBox.getItems() on my instance object myBox and easily get all the items it has.
I can make calls as
BoxModel.findOne({
where: { id: 1 },
include: [{ model: ItemModel }]
});
And it automatically understands there is a relation between the models through Box_Item and get everything correctly, except that I'm not getting the results sorted by item_order field. This field is a number from 1 to N that represents the item order inside that box.
I tried
BoxModel.findOne({
where: { id: 1 },
include: [
{
model: ItemModel,
order: 'item_order'
}
]
});
But it seems sequelizejs does not support order inside include yet (checked on their github repo).
I tried to force
BoxModel.findOne({
where: { id: 1 },
order: '`box_model`.`item_order`'
include: [ { model: ItemModel } ]
})
looking through the query sequelize creates but it just put the ORDER BY in two different places (inside INNER JOIN and at the end of the query, don't know why...) and I got an error.
So I searched for this on stackoverflow (1), found a few questions but I don't get a good way for doing that using the ORM.
How could I get the items sorted by item_order field when asking for specific box items?
After a few days trying to get it done I found an answer on stackoverflow that helped me.
After creating the relationships between Box and Item I can easily call on an instance:
myBox.getItems({
order: '`box_model`.`item_order`'
});
And then I get the result I'm expecting. But I had to look through the query sequelize is creating based on the models and get the correct field based on their renaming rules.
If you want you can pass the as parameter and rename your tables.
So, I'm using sequelize with a mysql instance and I have this hierarchy : a task has n images and also n metadata key value pairs.
I want to get all images based on userId column of task, and afterwards get them grouped by 'createdAt' column taking into consideration the day, since a normal groupby will be pointless ( no objects share the same datetime ). I did lots of test to try to group, and I ended up using this query, which gives bad results ( I have like 11 images for a task, and it retrieves 4 ). Honestly, i don't know what I'm doing wrong. Any of you have any idea?
This is the code snippet:
var userId = security.utils.getKeycloakSubject(req);
var where = {
userId: userId
};
db.image.findAll({
include: [{
model: db.task,
include: [{
model: db.metadata,
as: 'metadata'
}],
where: where
}],
group: [db.Sequelize.fn('DAY', db.Sequelize.col('image.createdAt'))]
}).then(function (images) {
return res.json(images);
}, function (error) {
return res.status(500).json(error);
})
I saw your question and also found this: Sequelize grouping by date, disregarding hours/minutes/seconds
It is a question about group the DAY(createdAt), looks similar with yours.
And my solution of GROUP BY DAY() is look like:
item.findAll({
attributes:
[[sequelize.fn('DATE_FORMAT', sequelize.col('TimeStamp'), '%H'), 'dates']],
group: [sequelize.fn('DAY', sequelize.col('TimeStamp'))]
}).
then(function(result){console.log(result)
}).
catch(function(error){}).catch(function(error) {
console.log(error);
});
So the raw SQL likes: SELECT DATE_FORMAT('TimeStamp', '%H') as 'dates' FROM tableName GROUP BY DAY('TimeStamp');
Hope it helps you, or you can show us the SQL you want to use, maybe it is easier to help you too.
Good luck.
I have a query I'm trying to perform based on a one to many relationship.
As an example there is a model called Users and one called Projects.
Users hasMany Projects
Projects have many types which are stored in a type (enum) column. There are 4 different types that potentially a user may have that I want to load. The catch is I want to include the most recent project record (createdAt column) for all networks that potentially will be there. I have not found a way to structure the query for it to work as an include. I have however found a way to do a raw query which does what I want.
I am looking for a way without having to do a raw query. By doing the raw query I have to map the returned results to users I've returned from the other method, or I have to do a simple include and then trim off all the results that are not the most recent. The latter is fine, but I see this getting slower as a user will have many projects and it will keep growing steadily.
This allow serialize a json for anywhere action about a model. Read it, very well
sequelize-virtual-fields
// define models
var Person = sequelize.define('Person', { name: Sequelize.STRING });
var Task = sequelize.define('Task', {
name: Sequelize.STRING,
nameWithPerson: {
type: Sequelize.VIRTUAL,
get: function() { return this.name + ' (' + this.Person.name + ')' }
attributes: [ 'name' ],
include: [ { model: Person, attributes: [ 'name' ] } ],
order: [ ['name'], [ Person, 'name' ] ]
}
});
// define associations
Task.belongsTo(Person);
Person.hasMany(Task);
// activate virtual fields functionality
sequelize.initVirtualFields();
Using sails 0.10.5/waterline 0.10.15:
I cannot find an answer to a simple question: how to count the elements of an association without using populate() (which would load all data).
Let take a simple many2many relation with via:
User:
attributes: {
following: {
collection: 'user',
via: 'follower',
dominant: true
},
follower: {
collection: 'user',
via: 'following'
}
Now I need the size of the collections.
Currently I try
User.findById(1).populateAll().exec(function(err, user) {
// count of followings -> user.following.length;
// count of followers-> user.follower.length;
}
which leads to loading the collections.
I'm missing a count function at collection level to avoid population/loading of data.
Is there a possibility to access the (auto generated) join tables to run a count-query directly on the join?
Something like:
User.findById(1).count({'followings'}).exec(function(err, followings) {
...}
or
UserFollowingFollow_FollowFollowing.countByUserFollowingFollowId(1).
exec(function(err, followings) {
...}
Waterline does offer the count query method and it can be used like this to solve your problem:
User.count().where({follower: followerId})
.exec(function(err, numberOfFollowings) {
//numberOfFollowings will be the integer that you need
})
followerId is the id that you are passing to User.findOne() in your example.
You can also read the Waterline documentation about this.