join - Rails create form for model with many to many relation - Stack Overflow
I am trying to create a many-to-many table relationship in a Rails 5 project. When I submit my Shop form, I receive the soft error: "Unpermitted. same time. You can watch this tutorial as a screencast Complex Forms in Rails 5. Declare the has_many tasks relationship in the project model. class Project You can now create a project with many tasks. The log file. I think the issue is this line @mephistolessiveur.info << params[:tags]. The association method you're calling with << takes an object (in this case expecting a tag object), but.
For example, if you had a Person model with an associated ContactDetail model, you could create a form for creating both like so: The Article model is directly available to users of the application, so - following the best practices for developing with Rails - you should declare it a resource: In short, you can just pass the model instance and have Rails figure out model name and the rest: Creating a new article long-style: Record identification is smart enough to figure out if the record is new by asking record.
It also selects the correct path to submit to and the name based on the class of the object. Rails will also automatically set the class and id of the form appropriately: These attributes will be omitted for brevity in the rest of this guide. When you're using STI single-table inheritance with your models, you can't rely on record identification on a subclass if only their parent class is declared a resource. You will have to specify the model name,: If you have several levels of namespacing then the syntax is similar: Here is what the markup might look like: Internally the application only wants to handle their IDs so they are used as the options' value attribute.
Let's see how Rails can help out here. The option value is what will be submitted to your controller. Often this will be the id of a corresponding database object but this does not have to be the case.
Whenever Rails sees that the internal value of an option being generated matches this value, it will add the selected attribute to that option. You can add arbitrary attributes to the options using hashes: One advantage here is that you don't have to worry about pre-selecting the correct city if the user already has one - Rails will do this for you by reading from the person. As with other helpers, if you were to use the select helper on a form builder scoped to the person object, the syntax would be: City expected, got String when you pass the params hash to Person.
Another way of looking at this is that form helpers only edit attributes. You should also be aware of the potential security ramifications of allowing users to edit foreign keys directly.RailsCasts - #47 Two Many-to-Many
But what if you had a City model perhaps an Active Record one and you wanted to generate option tags from a collection of those objects? One solution would be to make a nested array by iterating over them: This helper expects a collection of arbitrary objects and two additional arguments: Read the API documentation to learn about the possible arguments for these two methods.
When using this, be aware that the exclusion or inclusion of certain names from the list can be somewhat controversial and was the reason this functionality was extracted from Rails. These date and time helpers differ from all the other form helpers in two important respects: Dates and times are not representable by a single input element.
Instead you have several, one for each component year, month, day etc.
Both of these families of helpers will create a series of select boxes for the different components year, month, day etc. You may omit this parameter, in which case the current date is used.
To get an actual Date, Time or DateTime object you would have to extract these values and pass them to the appropriate constructor, for example: The model object helpers for dates and times submit parameters with special names; when Active Record sees parameters with such names it knows they must be combined with the other parameters and given to a constructor appropriate to the column type.
In particular, by default Rails will generate year options 5 years either side of the current year. If this is not an appropriate range, the: For an exhaustive list of the available options, refer to the API documentation. In many cases the built-in date pickers are clumsy as they do not aid the user in working out the relationship between the date and the day of the week. These helpers are fairly straightforward. The first parameter specifies which value should be selected and can either be an instance of a Date, Time or DateTime, in which case the relevant component will be extracted, or a numerical value.
The following two forms both upload a file. The only difference with other helpers is that you cannot set a default value for file inputs as this would have no meaning. As you would expect in the first case the uploaded file is in params[: Depending on the size of the uploaded file it may in fact be a StringIO or an instance of File backed by a temporary file.
The intricacies of this are beyond the scope of this guide, but there are several libraries designed to assist with these. Two of the better known ones are CarrierWave and Paperclip.
Building a has_many, through model relationship and form with Cocoon - HackHands
Note that the mass-assignment white-list on the join model also includes its own attribute of an: This allows easy access to the recipes that an ingredient is associated to via simple ingredient. Installing Cocoon to make nested forms easy-peasy To make setting up a nested form for a Recipe that can have 1 or more Ingredients each with a Quantity easy, we use a little gem called Cocoon.
Setting up the form code The tricky part of getting all this model magic to work of course is getting your nested form setup. Nested forms are a pain in the butt, but hopefully this will help get you rolling on your project. You can build your form with the helper of your choice, but I'm going to just use Rails' built in form helpers for this example to focus on the core of the setup instead of muddying the waters with a third-party helper. In this lesson, we'll look at some different ways we can create data from our complex associations to make for a great user experience.
Join Model Forms Sometimes, it may be appropriate for a user to create an instance of our join model directly. Think back to the hospital domain from our previous lab.
How to model a many-to-many relationship in rails
We're assigning these properties directly to the appointment as it's created. Other times, we need to be more abstract. Let's return to our blog example, but this time we'll say that a post can have many categories and categories can have many posts.
Let's look at a more abstract way that we can do this thanks to the magic of Active Record. We did this in a previous example without a join table. Our post was directly related to its category, and the posts table had the foreign key for its category.
We called upon this method from our form helpers to build out a nested form. The HTML generated looks something like this: This means that we can interact with our higher-level models directly without having to think too much at all about our join table - ActiveRecord will manage that relationship for us behind the scenes.