Skip to main content

Lifecycle Hooks

Elemental provides a way to inject custom logic into the lifecycle of a model. This is done by defining middleware functions that are executed at specific points in its lifecycle.

Middleware Functions

Middleware functions are model methods which you can invoke to register custom callbacks/handlers to be executed before or after certain operations. They are executed in the order they are defined.

You can define any number of middleware functions on a single model. Each middleware function is passed in necessary arguments as pointers related to the current operation such as the document being operated on or the filters being used. Since these arguments are pointers, you can modify them within the middleware function in any way you want.

Each middleware function returns a boolean value indicating whether the operation should continue or not. If the middleware function returns false, the operation will be aborted and no further middleware functions will be executed.

There are 2 categories of middleware functions in Elemental:

  1. Pre Middleware Functions: These functions are executed before an operation is performed on a model.
  2. Post Middleware Functions: These functions are executed after an operation is performed on a model.

Example Usage

WitcherModel.PreSave(func(witcher *bson.M) bool {
	fmt.Println("PreSave middleware executed", *witcher)
	return true
})

In the example above, we define a PreSave middleware function on the WitcherModel. This middleware function will be executed before a document is saved to the database.

Available Middleware Functions

Pre Middleware Functions

  • PreSave: Executed before a document is saved to the database.
  • PreUpdateOne: Executed before a single document is updated in the database.
  • PreDeleteOne: Executed before a single document is deleted from the database.
  • PreDeleteMany: Executed before multiple documents are deleted from the database.
  • PreFindOneAndUpdate: Executed before a single document is updated in the database.
  • PreFindOneAndDelete: Executed before a single document is deleted from the database.
  • PreFindOneAndReplace: Executed before a single document is replaced in the database.

Post Middleware Functions

  • PostSave: Executed after a document is saved to the database.
  • PostUpdateOne: Executed after a single document is updated in the database.
  • PostDeleteOne: Executed after a single document is deleted from the database.
  • PostDeleteMany: Executed after multiple documents are deleted from the database.
  • PostFind: Executed after documents are found in the database.
  • PostFindOneAndUpdate: Executed after a single document is updated in the database.
  • PostFindOneAndDelete: Executed after a single document is deleted from the database.
  • PostFindOneAndReplace: Executed after a single document is replaced in the database.