Define Frost Schema

The schema for The Frost Client is defined using the Frost Schema Language (FSL), a detailed guide on FSL can be found here.

Please checkout Types Definitions and Enums Definitions Sections in FSL guide

Before Defining Models create frost/schema.fsl file in your project directory, this will contain the schema.

Define the models

The syntax for defining a model is very similar for defining a Type except for a few differences.

• Start the definition with model keyword followed by the model name, As in lines [1,10].
• After the name of the model open two curly brackets which denotes the model block containing all the properties of that model
• define the properties of the model with this pattern <property_name> <property_type>
  • checkout the allowed property types in the "Allowed Data types" section in FSL quick guide.
  • properties could be optional by adding ? to the type
  • properties could be arrays by adding [] to the type

model Student {

  name String
  email String

  dateOfBirth Date 

}

model Course {

  level CourseLevel // a user-defined enum
  name String
  duration Int

}

Node database path

The node pragma is used to add any extra metadata for the node model. The path argument in the node pragma is used to determine the path of the node in the firebaseDB that will contain the list of the model nodes. if the node pragma is not used the path will default to the same name of the model.

As you can see in Lines 4 and 19, the node pragma is used to define the paths for each model

model Student {  name String  email String  // the students list will be stored in te following path in the database /students/<student_id>  @@node(path:'students')   dateOfBirth Date}model Course {  // the courses list will be stored in te following path in the database /courses/<course_id>  @@node(path:'courses')   level CourseLevel // a user-defined enum  name String  duration Int}

Defining the Relations

• Property definition statements in the model can accept the Relation modifier.
  • Other models can be used as data types in the model properties declaration, and actually you will have to use them if you want to decalre a relation between two models
• To connect two models, simply:
  • Define a property on each model with the type of the other model you want to connect to.
  • Add @Relation() after the property definition, as in Lines [10,26] in the code block below.
  • The Type of the relation is determined by the Data type (wheter it's an array or not):
    • Many To Many: if both sides are arrays
    • One To Many: if one side is an array and the other is not.
    • One To One: if both sides are not arrays
  • In the example below the relation is Many-to-Many due to both sides being array types.

info

You can define multiple relations between the same models; by passing the name of the relation to the name argument in the relation modifier, you can find a detailed guide here

model Student {// the students list will be stored in te following path in the database /students/<student_id>  @@node(path:'students')   name String  email String   dateOfBirth Date   courses Courses[] @Relation() // this property is used to define a relation with the Course model,// since the data type is model. you will find a corresponding property in the Course model// Since properties on both side are array types then the relation is `many to many`}model Course {  // the courses list will be stored in te following path in the database /courses/<course_id>  @@node(path:'courses')   level CourseLevel // a user-defined enum  name String  duration Int  students Student[] @Relation()}