If there are no errors or no identical tag is found, only then would you add the data. The alternative is to query the database before adding data and checking if a result returns. The catch (error) section is necessary for the insert because it will offload checking for duplicates to the database to notify you if an attempt to create a tag that already exists occurs. You are going to insert a tag name, description, and the author name into the database. create() method inserts some data into the model. Tags.create() uses the models that you created previously. You could potentially set it to be a blank or empty string, but it has to be something. Duplicate tag names are disallowed in this database.ĭefaultValue allows you to set a fallback value if there's no initial value during the insert.ĪllowNull is not all that important, but this will guarantee in the database that the attribute is never unset. Unique: true will ensure that this field will never have duplicated entries. The most common types are number, string, and date, but other data types are available depending on the database. Type refers to what kind of data this attribute should hold. Keys in the object become the model's attributes, and the values describe the attributes. 'tags' are passed as the name of our table, and an object that represents the table's schema in key-value pairs. There will be a table with four fields called name, description, username, and usage_count. The model mirrors very closely what the database defines. To do that in Sequelize, define a model based on this structure below the connection information, as shown below. The table in the database will look something like this: name This simple tag system will use four fields. In any relational database, you need to create tables to store your data. storage is a sqlite-only setting because sqlite is the only database that stores all its data to a single file. You can disable it by setting it to false. Logging enables verbose output from Sequelize–useful for when you are trying to debug. Otherwise, don't touch this unless you know what you're doing.ĭialect refers to the database engine you are going to use. If you have a remote database, however, then you can set it to that connection address. For most systems, the host will be localhost, as the database usually resides with the application. Host tells Sequelize where to look for the database. # Installing and using SequelizeĬreate a new project folder and run the following: Note that you will need Node 7.6 or above to utilize the async/await operators. We will explain SQlite as the first storage engine and show how to use other databases later. To begin, you should install Sequelize into your discord.js project. # A simple tag systemįor this tutorial, we will create a simple tag system that will allow you to add a tag, output a tag, edit a tag, show tag info, list tags, and delete a tag. You can create a database-agnostic query using an ORM that works on multiple database systems. Although databases generally adhere very closely to SQL, they each have their slight nuances and differences. As a side benefit, an ORM will enable you to write code that can run in almost every database system. The main benefit of using an ORM like Sequelize is that it allows you to write code that virtually looks like native JavaScript. Sequelize is an object-relational-mapper, which means you can write a query using objects and have it run on almost any other database system that Sequelize supports.
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