Prisma, how to see relational foreign key id?
They say when you do this
await ctx.prisma.post.create({
data: {
title: input.title,
content: input.content,
contentHtml: markdownToHtml(input.content),
author: {
connect: {
id: ctx.session.user.id,
},
},
},
})
It says "connect:" automatically connects. However, when I enter the database on planet scale and check, the corresponding column does not exist. How is this data permanently preserved? Also where can I extract it?
Related
I am using prisma + mysql (on planetscale). When I link two items that are in different tables, I normally use connect or disconnect:
const getUser = await prisma.user.update({
where: {
id: 9
},
data: {
posts: {
| connect: {
| id: 11
| },
create: {
title: "My new post title"
}
}
}
})
I am wondering whether that's necessary or why that's necessary?
I also noticed that I can just update records in my database by updating the id (as a plain string), and it will still work. e.g.:
// example for updating a one-to-many relationship:
const getUser = await prisma.user.update({
where: {
id: 9
},
data: {
postId: "123192312i39123123"
}
}
})
... or if it's an explicit many-to-many relation, I can just edit the row in the relation-table & update the id.
Is this a bad way of doing things? Am I going to break something later down the line in doing it this way?
Your cloud provider is not relevant in the context of the question. It will not affect how your framework(prisma) behaves in updates.
I am wondering whether that's necessary or why that's necessary?
You have a user with a one to many relation: user => n posts.
You have an existing post in the db, and you want to add that post to the posts collection of a user.
That posts relation can be either explicit or implicit. The connect clause handles the addition of relation:
{
posts: {
connect: { id: 11 }
}
}
Without using the connect you'd have to create a new post:
{
posts: {
create: {
title: "My new post title"
}
}
}
update records in my database by updating the id (as a plain string)
Not sure what you mean here, mind sharing the schema?
or if it's an explicit many-to-many relation, I can just edit the row in the relation-table & update the id
If it's explicit many-to-many then it's OK to manually edit the id fields. As long as the ids are found and the relation makes sense, there's no problem with manual updates.
I found out that sequelize is creating tables automatically according to the definition of my model names.
I have the following code:
const DataTypes = require("sequelize");
const sequelize = require("../mysql.js");
const Approver = sequelize.define("approver", {
subordinate_id: {
type: DataTypes.INTEGER,
allowNull: false,
references: {
model: "user",
key: "id",
},
},
leader_id: {
type: DataTypes.INTEGER,
allowNull: false,
references: {
model: "user",
key: "id",
},
},
main_leader_id: {
type: DataTypes.INTEGER,
allowNull: false,
references: {
model: "user",
key: "id",
},
},
});
const connect = async () => {
await Approver.sync();
};
connect();
module.exports = Approver;
every time I run the local server, I get the following message in the terminal:
CREATE TABLE IF NOT EXISTS `approvers` (`id` INTEGER NOT NULL auto_increment , `subordinate_id` INTEGER NOT NULL, `leader_id` INTEGER NOT NULL, `main_leader_id` INTEGER NOT NULL, `createdAt` DATETIME NOT NULL, `updatedAt` DATETIME NOT NULL, PRIMARY KEY (`id`), FOREIGN KEY (`subordinate_id`) REFERENCES `user` (`id`), FOREIGN KEY (`leader_id`) REFERENCES `user` (`id`), FOREIGN KEY (`main_leader_id`) REFERENCES `user` (`id`)) ENGINE=InnoDB;
and I found out that the table creation is generated from the model's define because I put other names in the model and the table created was the same as the one I had named the code.
I don't know why the table that is created is in the plural "approvers" and in the model I put the name "approver" and apparently if I try to put another name the plural doesn't happen as well as the word "approver".
the big problem is that I have migrations and when I run them the table "approver" is created in my database, but when I run the command to start the local server, the sequelize creates one more table. So I end up with 2 tables in the database, "approver" of the migration and "approvers" of the model.
I already tried to put the migration and the model with the plural name "approver" but this causes an error when I try to use the model, the sequelize shows a missing field error when I try to create or update data, it says that the value "updatedAt" is missing, and this only happens because the automatically generated table creates this field, but the funniest thing is that the table was not created in my Dbeaver but the sequelize shows the error of being missing a field, even the model containing the plural name and the migration too...
I would like to get the result that the table is not created with the plural.
does anyone know how to solve this bug?
enter image description here
You have two problems here:
An auto-creation of a table according to a model definition
Pluralization of a table name while auto-creating it
Solutions:
Just remove sync call or the whole piece of the following code:
const connect = async () => {
await Approver.sync();
};
connect();
If you use migrations to create the whole structure and to make modifications to it then you don't need to use sync method of a model or a Sequelize instance.
Pluralization of table names can be turned off by indicating 'freezeTableName: true' in the model's options (see Enforcing table name to be equal to a model name in the official documentation).
i am new in Loopback 4
I followed this tutorial to get started and everything worked fine.
I tried to create my own models Category and SubCategory using a MySQL database, with one to many relation (one category has many sub categories), i have noticed that it did create a field in subcategory table (categoryId) but the foreign key index is missing.
can someone help?
LoopBack 4 does not implicitly add foreign key constraints. This is to allow weak cross-datasource relations (e.g. a relation between PostgreSQL & Oracle).
Hence, the responsibility falls on the connectors to provide an interface to define these constraints. This however, means that there isn't a consistent interface across different connectors. There is an open issue to track this.
In the case of MySQL:
#model({
settings: {
foreignKeys: {
categorySubCategoryFK: {
name: 'categorySubCategoryFK',
entity: 'Category',
entityKey: 'id',
foreignKey: 'categoryId',
},
},
},
})
In case auto-migration is used (which it should not be used in production!), migrate.ts would need to be updated to define explicit ordering of the schemas:
await app.migrateSchema({
existingSchema,
models: ['Category', 'SubCategory'],
});
Further reading
https://loopback.io/doc/en/lb4/todo-list-tutorial-sqldb.html#specify-the-foreign-key-constraints-in-todo-model
https://loopback.io/doc/en/lb4/MySQL-connector.html
found the answer here, besides adding the settings to #model annotation, like so
#model({
settings: {
foreignKeys: {
categorySubCategoryFK: {
name: 'categorySubCategoryFK',
entity: 'Category',
entityKey: 'id',
foreignKey: 'categoryId',
},
},
},
})
you have to change to specify in which order tables should be created in migrate.ts and change this
await app.migrateSchema({existingSchema});
to this
await app.migrateSchema({
existingSchema,
models: ['Category', 'SubCategory'],
});
more details here
Loopback 4 creates relation on models and Api's not on database. Thus it won't get reflected on your mysql database
I have a following table. I don't want user to follow himself so I want to add a CHECK constraint.
For example, if this is inserted, I want database to throw an error.
{
userID: 1,
followingID: 1,
}
I can check with Javascript if userID and followingID are equal but I want database to check it.
My MYSQL version is 8.0.17 so I think it is possible to create this constraint with SQL. How can I add this constraint with Sequelize?
There is two solution
1. Using Model wise validation and adding check constraint in database manually:
Model wise validation:
const FollowingModel = sequelize.define("following", {
userId: {
type: Sequelize.INTEGER,
// .. other configuration like `allowNull`
},
followingId: {
type: Sequelize.INTEGER,
// .. other configuration like `allowNull`
}
}, {
validate: {
userShouldNotFollowSelf : function() {
if(this.userId === this.followingId) {
throw Error("User should not follow self") // Use any custom error class if your application has such class.
}
}
}
}
Beware this will allow you create entry in database which does not maintain this constraint.
It is just ORM's application layer check that, this application won't allow any entry where userId and followingId is not same.
Mysql database layer check constraint.
CREATE TABLE `following`
(
`userId` INT NOT NULL,
`followingId` INT NOT NULL,
CONSTRAINT `no_self_following` CHECK (`userId` <> `followingId`)
-- other properties and foreign key constraints.
);
It will ensure that, no such entry inserted where userId and followingId is same.
2. Declaring constraint in sequelize query interface.
This require to declare your model using query interfaces addConstraint as follows
sequelize.getQueryInterface().addConstraint("following", ['userId'], {
type: 'check',
name: "no_self_following"
where: {
userId: {
[Sequelize.Op.ne]: Sequelize.col("followingId")
}
}
});
Run this while all database model is been synced correctly. It will add database level constraint.
Which one to use ?
Approach #1 is more efficient. It is checking within the application without going into the database call, Makes your database less busy.
I think I've done enough research on this subject and I've only got a headache.
Here is what I have done and understood: I have restructured my MySQL database so that I will keep my user's data in different tables, I am using foreign keys. Until now I only concluded that foreign keys are only used for consistency and control and they do not automatize or do anything else (for example, to insert data about the same user in two tables I need to use two separate insert statements and the foreign key will not help to make this different or automatic in some way).
Fine. Here is what I want to do: I want to use Sequelize to insert, update and retrieve data altogether from all the related tables at once and I have absolutely no idea on how to do that. For example, if a user registers, I want to be able to insert the data in the table "A" containing some user information and in the same task insert in the table B some other data (like the user's settings in the dedicated table or whatever). Same with retrievals, I want to be able to get an object (or array) with all the related data from different tables fitting in the criteria I want to find by.
Sequelize documentation covers the things in a way that every thing depends on the previous one, and Sequelize is pretty bloated with a lot of stuff I do not need. I do not want to use .sync(). I do not want to use migrations. I have the structure of my database created already and I want Sequelize to attach to it.
Is it possible insert and retrieve several rows related at the same time and getting / using a single Sequelize command / object? How?
Again, by "related data" I mean data "linked" by sharing the same foreign key.
Is it possible insert and retrieve several rows related at the same
time and getting / using a single Sequelize command / object? How?
Yes. What you need is eager loading.
Look at the following example
const User = sequelize.define('user', {
username: Sequelize.STRING,
});
const Address = sequelize.define('add', {
address: Sequelize.STRING,
});
const Designation = sequelize.define('designation', {
designation: Sequelize.STRING,
});
User.hasOne(Address);
User.hasMany(Designation);
sequelize.sync({ force: true })
.then(() => User.create({
username: 'test123',
add: {
address: 'this is dummy address'
},
designations: [
{ designation: 'designation1' },
{ designation: 'designation2' },
],
}, { include: [Address, Designation] }))
.then(user => {
User.findAll({
include: [Address, Designation],
}).then((result) => {
console.log(result);
});
});
In console.log, you will get all the data with all its associated models that you want to include in the query