I have table Forums and entity Forum. But when I doing query to this table, Entity Framework generation query to table Fora. When in entity class Forum add attribute Table("Forums") I get proper query. Why this happens?
This is actually not a bug, the proper english plural form of Forum is Fora. However, you kind of answered your own questions. You can indeed solve it by adding an attribute Table("Forums").
Source: http://en.wiktionary.org/wiki/forum#English
Related
In a Django application, I have three models:
Service
Product
AppliedTax
I want to create a many-to-many relationship between Service and AppliedTax and between Product and AppliedTax. Normally I would have an intermediate model (i.e. AppliedTaxTaxable) with three fields (applied_tax_id, taxable_type and taxable_id) and taxable_type + taxable_id would be a composite foreign key for each related model with taxable_type having as value the name of the related model (Service or Product in my case) and the taxable_id field the id of the related record of the respective model.
I understand how to make it work with raw queries, but Is there a "Django" way to do that with a ManyToMany relationship? So far I had no luck with that. I don't have much experience with Django, but I hope there is a way to do that without using raw queries.
Help :)
Well, after some thought, I did a better search and stumbled upon django-polymorphic. Here is a pretty straightforward explanation on how it works, for a basic set up and it does what I am describing in my question. The implemented schema differs a bit from what my description, but in the end we will home one intermediate table for all associated models.
I have a model for articles with various attributes like author, title, etc. One of the attributes is "comments_on" for all of the articles that the article in question (let's call it "main article" for now) is responding to.
I use a reciprocal many-to-many relationship to represent this.
I know how to display on a website all of the articles that the main article comments on. I would like to know if it's possible to display all of the articles that have commented on the main article.
I assume I don't need to create a separate field in my model for this, since the relationship between the main article and other articles that comment on the main article is reflected in the same reciprocal many-to-many relationship.
Any idea what the code for this is will be? Thank you.
I think you're looking for related_name.
Why does the TYPO3 Extension Builder don't generate Foreign keys?
I've set some relations between the models, but in SQL Code there are noe FKs only colums for the Value of the key.
Does anyone can help me?
Cite from Kartsen Dambekalns
It is a half-conscious design decision. Just look up the date when
foreign key constraints where introduced in MySQL, and compare to when
TYPO3 was 'born'.
Of course it would be great to add such references, especially since
MySQL can always handle themm, even if the underlying storage engine
doesn't handle them (in case of which they'll just be ignored).
(source)
Nothing changed till now, so you need to create foreign keys yourself after modeling.
Answer to comment:
how did you handle the relations between two tables? for example I've got a table people which relates to the table house with the column housenr
That depends on relation type of course (1:n, n:1, m:n, etc) and Builder supports creating relations in modeling tool perfectly. Keep in mind, that foreign keys are NOT required for keeping relations in TYPO3.
There are some rules described in TCA section of documentation, i.e. in mentioned case you can use select or group (with internal_type) type of field. For many-to-many relation also you'll need to create MM table. If you'll follow these documents, you can be sure, that in common backend editing form they will be handled properly.
As mentioned before Extension Builder supports creating different types of relations in its click-click modeling tool and it's worthy to spend some time to play with it to see how relations of different types are handled in TYPO3. It uses the same rules that are used in creating relations also in pre-extbase extensions. What's more Builder adds required methods to the models i.e. for getting, attaching and detaching MM objects of given relation field, therefore it's most important to model all your relations at start. In other case you'll need to write these methods manually (which is boring process)
Summary
I have a bit of a problem using Ember-Model, trying to establish a unique relationship between two models.
Based on current responses that I have received here on S.O., Ember Forums, and #emberjs. I am beginning to believe that there is no built-in solution for this problem, and I am reformatting my question to specify what is needed.
Details
I am populating a template currently with a full set of debtor information. All the information comes from multiple calls to the server.
The first bit is the basic Debtor info. This part is easy because I can use the model hook and a dynamic segment to retrieve it.
My server returns a JSON for a Debtor... Here's the short version:
{
"debtor" = {
"debtor_id": 1003,
"debtor_name": Steve,
//... more JSON
"debtor_contact_id": 1345
}
}
The dynamic segment for Debtor is filled with the value of the debtor_id, but also notice this debtor has a debtor_contact_id. Every Debtor record retrieved from the server has a unique debtor_contact_id. On the database, this value is a "foreign key" that will tell which contact table belongs to which debtor table.
There is no way to predict which contact info relates to which debtor without this key/value pair.
I currently have "Contacts" belongsTo "Debtor", but that is not enough to do the job.
When it is time to fill the "Contacts" model. Ember-Model needs to know to build the value from debtor_contact_id into the ajax URL as a query parameter in order to GET the correct API.
I am still learning all of this stuff and so far I have not been able to fully follow any tutorials because my use case has an extra step needed somewhere.
This is the expected behavior I am hoping to see:
Model hook will work as expected to pull the specific debtor and put it into a "debtor" model (this part is currently working just fine)
Somehow "debtor_contact_id" is read from the payload
that value is added as part of a server query to find a separate API
the resulting contact info will be pulled into a "contact" model
hopefully a hasMany/belongsTo relationship can be established after both corresponding models are returned.
all this needs to be done in one promise before entering my template
You will also find the question at: discuss.emberjs.com if that is more appropriate place to discuss.
I can elaborate more if this does not make sense... thanks!
Assuming you are using ember-data, alongside the attributes of your model you need to add:
debtor_contact: DS.belongsTo('name_of_the_other_model')
This then provides you a promise which will resolve to the other model on demand. It won't resolve straight away, but bound variables in templates will update as it is resolved. The other API call will be made for you if things are set up properly.
http://emberjs.com/api/data/classes/DS.html#method_belongsTo
The answer I gave here might also be helpful if you need to force resolving the relationship for some reason: Ember Unbound & Belongsto
I'm porting a project from Rails to Django with a legacy database. In Rails I had a polymorphic association that allowed me to add a footnote to any row in the database. I'm trying to implement the same thing in the Django app. I found the documentation on Generic Relations and it looks perfect. Unfortunately, I first need to create new fields in my legacy database to hold the ContentType id for the relevant models. I only used the polymorphic association with 2 tables, so all I need are those two corresponding ids from the Django app, but I can't seem to find the appropriate command for looking up a ContentType id in Django.
Any suggestions are most welcome. I tried searching through previous questions but couldn't seem to find what I am looking for. Thank you very much for you time and help.
from the docs
you can do:
>>> b = Bookmark.objects.get(url='https://www.djangoproject.com/')
>>> bookmark_type = ContentType.objects.get_for_model(b)
>>> TaggedItem.objects.filter(content_type__pk=bookmark_type.id,
... object_id=b.id)
so just instantiate an instance of your model and then do ContentType.objects.get_for_model(<instance>).id
I think there's a way to pass just the model name, too... let me know if that would work better and I'll try to find it; I've used it in the past.
You can also get ContentType ID without creating an instance, which is more efficient if you don't have and don't need an instance but just want to get ContentType ID by model name.
ContentType.objects.get(model='bookmark').id
Notes : if the name of your model is upper case, please use lower case to search. For example: model = 'bookmark' rather than 'Bookmark'