Lets say I want to track employees working on projects.
Project 2015
- Employee A
Employee A now changes his healthcare-provider,
address and completes his bachelor degree.
Project 2018
- Employee A
For Project 2018 the Employee A details are up to date. But if I look
back at project 2015 the Employee A details are now newer than the Project itself. For example now it looks like Employee A had a bachelors degree when working at Project 2015, which is incorrect.
What I need is like an instance of Employee A frozen in time/time capsule/snapshot/copy when saving him to a Project. While still being able to update the "live" version of the employee.
There are other models where I will run into the same problem. It really boggles my mind, because it's so counterintuitive for database-thinking. Is there a right/correct way to handle this. Is there maybe a Django revision? solution? Thank You!
The project django-simple-history is very useful and you can have snapshots of your objects.
I had similiar challenges and we worked it out by doing a pattern that would rougly translate to this domain as:
class EmployeeProfile(Model):
class Meta:
abstract = True
common_field1 = CharField()
common_field2 = CharField()
common_field3 = CharField()
def get_employee_profile_data(self):
return {
'common_field1': self.common_field1,
'common_field2': self.common_field2,
'common_field3': self.common_field3,
}
class Employee(EmployeeProfile):
specific_fields
class ProjectProfile(EmployeeProfile):
class Meta:
unique_together = ('project', 'employee')
project = ForeignKey(Project)
owner = ForeignKey(Employee) # Means that the Employee "owns" this profile
# A factory function
def create_project_profile(employee, project):
return ProjectProfile.objects.create(
project=project,
owner=employee,
**employee.get_employee_profile_data())
We tried to think with separation of concern in mind.
I this scenario I think the pattern fulfills the following:
A project have project specific profile which is owned by an Employee
An employee can only have one profile per project
It is possible to change the specific profile for a project without affecting the "live data"
It is possible to change an employee profile live data without affecting any project
Benefits are that database migrations will affect both Employee and the ProjectProfile and it should be simple to put get_employee_profile_data under unittest.
The owner reference will make sure it's easy to query for participants etc for projects.
Hope it can give some ideas...
Related
First of all I am really not very familiar with the REST practice, and I am not very confident about the title of my question.
So I am trying to built a RESTful API using Laravel for a phonebook application. The phonebook may contain telephones of either employees (i.e real persons) or offices. For that reason I have three models
a Directorate with id and name fields,
an Employee with id and name fields and
a Telephone with id, tel, employee_id, directorate_id, description and type fields.
Telephones corresponding to a directorate's office have only the id, tel, directorate_id and description fields set, while the telephones corresponding to a person (i.e an employee) have set only the id, tel, employee_id, directorate_id, and type fields. That is how I separate them: a telephone having a description can only be an office's telephone, while a telephone having both the employee_id and the type_id set is an employee's telephone.
The models are related as follows:
an employee may have many telephones
a directorate, may have many telephones
class Directorate extends Model
{
public function telephones()
{
return $this->hasMany(Telephone::class);
}
public function employees()
{
return $this->hasMany(Employee::class);
}
}
class Employee extends Model
{
public function telephones()
{
return $this->hasMany(Telephone::class);
}
public function directorate()
{
return $this->belongTo(Directorate::class);
}
}
class Telephone extends Model
{
public function employee()
{
return $this->belongsTo(Employee::class);
}
}
My question is what should I a consider as my resource.
So far I am thinking of the following approach:
I shall use the concept of contact as resource. A contact may be the joined information of either an employee and a telephone, or a directorate and a telephone. For instance, a "contact" may contain the name of an employee with his related telephone numbers and telephone types, or it can contain the name of a directorate with the description of the telephone and the telephone number.
The "problem" with this approach is that I have ended up with (let's put it this way) two different types of resource: the employee's contacts and the directorate office's contacts, which contain slightly different information and thus, I need also to have different create and edit forms to interact with these two "types" of resources.
In order to implement the REST API, I am thinking of two different scenarios:
Use two different RESTful controllers, one EmployeeContacts and another OfficesContacts for separating conceptually the resource to an employee's and an office's resource, and accessing them through different URIs like:
example.com/phonebook/employees/{id}/edit
example.com/phonebook/offices/{id}/edit
example.com/phonebook/employees/create
etc...
Use a single RESTful controller, e.g. PhonebookContacts to access the resources through the same URIs as one resource (i.e. both employee's and office's contact resources now are considered to be just a "contact" resource)
//this refers to a contact resource that can be either an office's or a n employee's contact
example.com/phonebook/contact/{id}/edit
//this should list all resources (both employees and offices contacts)
example.com/phonebook/contact/
and then use conditional statements in the controller's create/store/edit/update methods to deal with them separately (e.g if an http POST request contains a description_id then it is an office contact and do this, or else if has an employee_id then it is an employee's contact so do that...)
I would like to hear your views, what of these two different scenarios do you consider to be better in the context of REST for my phonebook app? Would be better to think of a single "contact" resource and handle it using conditional statements with different return in the controller, or shall I separate the concept of "contact" to "employee's contact" and "office's contact" and use separate controllers and URI's to handle them?
Is there another approach that I could follow instead?
The way I would do it is with 2 different controllers for the simple reason of speed and responsiveness. Loading all contacts and filtering isn't as quick as loading the one part only.
However, you can always set in your controller the same return with different data. Such as EmployeeController#index returns view('contacts.index', compact('employeeContacts')), and OfficesController#index returns view('contacts.index', compact('officesContacts'))
EDIT:
Sorry, I have misread it...I thought you wanted to do the filtering in the view. Anyway, my practice is to do it separately, simply because the code is cleaner. If you want to make the whole REST more readable, you can put both resources in a group like so: Route::group(['prefix' => 'contact'], function(){ //routes here// });
So now you will have routes like:
example.com/contact/employees/
example.com/contact/offices/
I am not familiar at all with Laravel but since this question is about REST concepts (I have a small background on these) I should give it a try.
Since you are building a RESTful application, you must not consider others as human beings but only as machines. IMO the urls should determine the action that will be performed. Thus, by using different urls for different actions (perform a CRUD on a contact - either an Employee or a Directorate or SomethingElseInTheFuture) sounds good to me and fits the REST nice.
Hope this clarify the things for you!
[EDIT]
I believe jannis is right. It should be the verbs (GET, POST, PUT, PATCH etc) that make the action instead of the URLs. The urls are just respresenting the resources. My mistake. So both of your points of view are correct. It's just how convenient each approach is for your project (for now and for the near future of your project). IMO, I see #1 (two different restful controllers) more approchable.
Cheers and sorry for any misconception!
While creating an app in Laravel 4 after reading T. Otwell's book on good design patterns in Laravel I found myself creating repositories for every table on the application.
I ended up with the following table structure:
Students: id, name
Courses: id, name, teacher_id
Teachers: id, name
Assignments: id, name, course_id
Scores (acts as a pivot between students and assignments): student_id, assignment_id, scores
I have repository classes with find, create, update and delete methods for all of these tables. Each repository has an Eloquent model which interacts with the database. Relationships are defined in the model per Laravel's documentation: http://laravel.com/docs/eloquent#relationships.
When creating a new course, all I do is calling the create method on the Course Repository. That course has assignments, so when creating one, I also want to create an entry in the score's table for each student in the course. I do this through the Assignment Repository. This implies the assignment repository communicates with two Eloquent models, with the Assignment and Student model.
My question is: as this app will probably grow in size and more relationships will be introduced, is it good practice to communicate with different Eloquent models in repositories or should this be done using other repositories instead (I mean calling other repositories from the Assignment repository) or should it be done in the Eloquent models all together?
Also, is it good practice to use the scores table as a pivot between assignments and students or should it be done somewhere else?
I am finishing up a large project using Laravel 4 and had to answer all of the questions you are asking right now. After reading all of the available Laravel books over at Leanpub, and tons of Googling, I came up with the following structure.
One Eloquent Model class per datable table
One Repository class per Eloquent Model
A Service class that may communicate between multiple Repository classes.
So let's say I'm building a movie database. I would have at least the following following Eloquent Model classes:
Movie
Studio
Director
Actor
Review
A repository class would encapsulate each Eloquent Model class and be responsible for CRUD operations on the database. The repository classes might look like this:
MovieRepository
StudioRepository
DirectorRepository
ActorRepository
ReviewRepository
Each repository class would extend a BaseRepository class which implements the following interface:
interface BaseRepositoryInterface
{
public function errors();
public function all(array $related = null);
public function get($id, array $related = null);
public function getWhere($column, $value, array $related = null);
public function getRecent($limit, array $related = null);
public function create(array $data);
public function update(array $data);
public function delete($id);
public function deleteWhere($column, $value);
}
A Service class is used to glue multiple repositories together and contains the real "business logic" of the application. Controllers only communicate with Service classes for Create, Update and Delete actions.
So when I want to create a new Movie record in the database, my MovieController class might have the following methods:
public function __construct(MovieRepositoryInterface $movieRepository, MovieServiceInterface $movieService)
{
$this->movieRepository = $movieRepository;
$this->movieService = $movieService;
}
public function postCreate()
{
if( ! $this->movieService->create(Input::all()))
{
return Redirect::back()->withErrors($this->movieService->errors())->withInput();
}
// New movie was saved successfully. Do whatever you need to do here.
}
It's up to you to determine how you POST data to your controllers, but let's say the data returned by Input::all() in the postCreate() method looks something like this:
$data = array(
'movie' => array(
'title' => 'Iron Eagle',
'year' => '1986',
'synopsis' => 'When Doug\'s father, an Air Force Pilot, is shot down by MiGs belonging to a radical Middle Eastern state, no one seems able to get him out. Doug finds Chappy, an Air Force Colonel who is intrigued by the idea of sending in two fighters piloted by himself and Doug to rescue Doug\'s father after bombing the MiG base.'
),
'actors' => array(
0 => 'Louis Gossett Jr.',
1 => 'Jason Gedrick',
2 => 'Larry B. Scott'
),
'director' => 'Sidney J. Furie',
'studio' => 'TriStar Pictures'
)
Since the MovieRepository shouldn't know how to create Actor, Director or Studio records in the database, we'll use our MovieService class, which might look something like this:
public function __construct(MovieRepositoryInterface $movieRepository, ActorRepositoryInterface $actorRepository, DirectorRepositoryInterface $directorRepository, StudioRepositoryInterface $studioRepository)
{
$this->movieRepository = $movieRepository;
$this->actorRepository = $actorRepository;
$this->directorRepository = $directorRepository;
$this->studioRepository = $studioRepository;
}
public function create(array $input)
{
$movieData = $input['movie'];
$actorsData = $input['actors'];
$directorData = $input['director'];
$studioData = $input['studio'];
// In a more complete example you would probably want to implement database transactions and perform input validation using the Laravel Validator class here.
// Create the new movie record
$movie = $this->movieRepository->create($movieData);
// Create the new actor records and associate them with the movie record
foreach($actors as $actor)
{
$actorModel = $this->actorRepository->create($actor);
$movie->actors()->save($actorModel);
}
// Create the director record and associate it with the movie record
$director = $this->directorRepository->create($directorData);
$director->movies()->associate($movie);
// Create the studio record and associate it with the movie record
$studio = $this->studioRepository->create($studioData);
$studio->movies()->associate($movie);
// Assume everything worked. In the real world you'll need to implement checks.
return true;
}
So what we're left with is a nice, sensible separation of concerns. Repositories are only aware of the Eloquent model they insert and retrieve from the database. Controllers don't care about repositories, they just hand off the data they collect from the user and pass it to the appropriate service. The service doesn't care how the data it receives is saved to the database, it just hands off the relevant data it was given by the controller to the appropriate repositories.
Keep in mind you're asking for opinions :D
Here's mine:
TL;DR: Yes, that's fine.
You're doing fine!
I do exactly what you are doing often and find it works great.
I often, however, organize repositories around business logic instead of having a repo-per-table. This is useful as it's a point of view centered around how your application should solve your "business problem".
A Course is a "entity", with attributes (title, id, etc) and even other entities (Assignments, which have their own attributes and possibly entities).
Your "Course" repository should be able to return a Course and the Courses' attributes/Assignments (including Assignment).
You can accomplish that with Eloquent, luckily.
(I often end up with a repository per table, but some repositories are used much more than others, and so have many more methods. Your "courses" repository may be much more full-featured than your Assignments repository, for instance, if your application centers more around Courses and less about a Courses' collection of Assignments).
The tricky part
I often use repositories inside of my repositories in order to do some database actions.
Any repository which implements Eloquent in order to handle data will likely return Eloquent models. In that light, it's fine if your Course model uses built-in relationships in order to retrieve or save Assignments (or any other use case). Our "implementation" is built around Eloquent.
From a practical point of view, this makes sense. We're unlikely to change data sources to something Eloquent can't handle (to a non-sql data source).
ORMS
The trickiest part of this setup, for me at least, is determing if Eloquent is actually helping or harming us. ORMs are a tricky subject, because while they help us greatly from a practical point of view, they also couple your "business logic entities" code with the code doing the data retrieval.
This sort of muddles up whether your repository's responsibility is actually for handling data or handling the retrieval / update of entities (business domain entities).
Furthermore, they act as the very objects you pass to your views. If you later have to get away from using Eloquent models in a repository, you'll need to make sure the variables passed to your views behave in the same way or have the same methods available, otherwise changing your data sources will roll into changing your views, and you've (partially) lost the purpose of abstracting your logic out to repositories in the first place - the maintainability of your project goes down as.
Anyway, these are somewhat incomplete thoughts. They are, as stated, merely my opinion, which happens to be the result of reading Domain Driven Design and watching videos like "uncle bob's" keynote at Ruby Midwest within the last year.
I like to think of it in terms of what my code is doing and what it is responsible for, rather than "right or wrong". This is how I break apart my responsibilities:
Controllers are the HTTP layer and route requests through to the underlying apis (aka, it controls the flow)
Models represent the database schema, and tell the application what the data looks like, what relationships it may have, as well as any global attributes that may be necessary (such as a name method for returning a concatenated first and last name)
Repositories represent the more complex queries and interactions with the models (I don't do any queries on model methods).
Search engines - classes that help me build complex search queries.
With this in mind, it makes sense every time to use a repository (whether you create interfaces.etc. is a whole other topic). I like this approach, because it means I know exactly where to go when I'm needing to do certain work.
I also tend to build a base repository, usually an abstract class which defines the main defaults - basically CRUD operations, and then each child can just extend and add methods as necessary, or overload the defaults. Injecting your model also helps this pattern to be quite robust.
Think of Repositories as a consistent filing cabinet of your data (not just your ORMs). The idea is that you want to grab data in a consistent simple to use API.
If you find yourself just doing Model::all(), Model::find(), Model::create() you probably won't benefit much from abstracting away a repository. On the other hand, if you want to do a bit more business logic to your queries or actions, you may want to create a repository to make an easier to use API for dealing with data.
I think you were asking if a repository would be the best way to deal with some of the more verbose syntax required to connect related models. Depending on the situation, there are a few things I may do:
Hanging a new child model off of a parent model (one-one or one-many), I would add a method to the child repository something like createWithParent($attributes, $parentModelInstance) and this would just add the $parentModelInstance->id into the parent_id field of the attributes and call create.
Attaching a many-many relationship, I actually create functions on the models so that I can run $instance->attachChild($childInstance). Note that this requires existing elements on both side.
Creating related models in one run, I create something that I call a Gateway (it may be a bit off from Fowler's definitions). Way I can call $gateway->createParentAndChild($parentAttributes, $childAttributes) instead of a bunch of logic that may change or that would complicate the logic that I have in a controller or command.
Hi guys I have a situation where on a form I'm taking in orders for a car servicing application. I have the following models:
Car
belongs_to :car_company
Car_company
has_many :cars
Services
attributes_accessible :car_company_id, :car_id
#virtual attributes
attributes_accessible :car_company_name, :car_reg
The thing is that on a single form the user can enter in the name of the car company as well as the registration number of a car. If the company name doesnt exist it creates a new company and associates it with the service and the same goes for the car. I got this part working however the thing is that I want that on submitting this form the car created should be automatically associated with the car_company whether the carcompany exists or doesn't exist.
I'm pretty stuck here on how to get this thing done the right way? Its basically just to avoid having to enter the car details and the company details seperately just to use them on a form. Any ideas guys?
I see you are using an unconventional model name. By convention in rails, your model should be CarCompany. However, I think what you have will work.
Putting something like this in the appropriate controller may be something like what you want. If not, please clarify what you want.
car_company = Car_company.find_or_initialize_by_name(params[:car_company_name])
car = Car.find_or_initialize_by_registration(params[:car_registration])
car_company.cars << car
car_company.save
You actually may be able to combine the middle two lines with car_company.cars.find_or..., but I'm not sure if that works or not.
I hope that helps.
First, some background:
I have a Company model, a Project model and a Task model. A Project belongs to a company and a Task belongs_to a Project.
The Project model holds several attributes: company_id, date. These attributes uniquely identify a project
I am letting the users create a task by API by POSTing to a URL that contains the details necessary to identify the Project. For example:
POST /projects/<comnpany_name>/<date>/tasks/
In order to make life easier for the users, in case there is no project with the given details, I'd like to create the project on the fly by the given details, and then to create the task and assign it to the project.
...And my problem is:
When there is a problem to create the project, let's say that the company name is not valid, what is the right way to return the error message and communicate to the user?
I'll explain what I mean: I added a create_by_name_and_company_name method to the Project:
def self.create_by_name_and_company_name(name, company_name)
if company = Company.find_by_name(company_name)
project = Project.create(company_id: company.id,
name: name)
else # cannot create this project, trying to communicate the error
project = Project.new(name: name)
project.errors.add(:company, 'must have a valid name')
end
company
end
I was hoping that by returning an unsaved Company object, with errors set, will be a good way communicate the error (This is similar to how rails work when there's a validation error).
The problem is that when calling valid? on the company object, it removed the error I wrote there and adds the regular validation errors (in this case, company can't be blank).
And a bonus question...
And there is a conceptual problem as well: since I'm creating a model by providing parameters that are being used to create the actual attributes, they doesn't always map nicely to the errors[:attr] hash. In this case it is not so bad and I'm using the company field for the company name parameter, but I guess this can get messier when the parameters provided to the create method are less similar to the model attributes.
So what is the preferred approach to tackle that problem? Is there something basically wrong with that approach? if so, what is the preferred approach?
About overriding the default rails validation error message, you need to write your validation constraint like this:
validates_presence_of :name, :message => "must be a valid name"
I figure that it is best to avoid such nesting and stick to a shallower API.
how can I get all accounts of am employee?
In the "Siebel Object Interaces Reference" I found an example, how to get all industries of an account:
var myAccountBO = TheApplication().GetBusObject("Account");
var myAccountBC = myAccountBO.GetBusComp("Account");
var myAssocBC = myAccountBC.GetMVGBusComp("Industry");
So I would like to do something like:
var myEmployeeBO = TheApplication().GetBusObject("Employee");
var myEmployeeBC = myAccountBO.GetBusComp("Employee");
var myAssocBC = myAccountBC.GetMVGBusComp("Account");
But I get an error
Semantic Warning around line 23:No such predefined property Account in class BusComp[Employee].MVGFields.
I can see in Tools that there is no Multi Value Link called "Account" in Business Component "Employee", so I can actually understand the error message.
So I wonder how I can get all accounts of an employee.
I found the Business Component "User" which has a Multi Value Link to "Organisation" and another link "User/Account".
Is this what I am looking for?
How can I know? Where is documentation which tells me about the semantics of links? (Is this described in "Siebel data model reference"? I cannot download this document, although I have signed in...) This link could also link a user to the organization it belongs to.
If one of these links IS what I am looking for, what would be the way to go to get the "User" Business Component of a corresponding "Employee" Business Component?
Many questions of a Siebel newb...Thanks for your patience.
Nang. An easy way to approach this (and to learn it) is to figure out how you'd do it in the UI. Then move onto figuring out how to do the same thing in script.
When you say, "get all account of an employee," do you really mean get all accounts where a particular employee is on the account team? In the UI, that would be done by going to: Accounts > All Accounts Across Organizations, and querying for that specific user in the "Account Team" multi-value field.
From that same view, go to Help > About View in the application menu. You'll see in the popup that the view uses the Account business object and the Account business component. A quick examination of the applet you queried on will show you that the "Account Team" field on the applet is really the "Sales Rep" field on the Account business component. Here's how to mimic what we did in the UI, in script:
var boAccount = TheApplication().GetBusObject("Account");
var bcAccount = boAccount.GetBusComp("Account");
bcAccount.SetViewMode(AllView); // like All .. Across Orgs
bcAccount.ClearToQuery();
bcAccount.SetSearchSpec("Sales Rep", "NANG");
bcAccount.ExecuteQuery();
Then you can walk through the list of accounts and do something with each one like this:
// for each account
for (var bIsRowActive = bcAccount.FirstRecord();
bIsRowActive; b = bcAccount.NextRecord())
{
// do something here
}
I hope you're enjoying Siebel.