I just wanted to validate my data structure.
It seems a bit convoluted to me, maybe it can be simplified?
Questions are grouped into chapters.
For each question, only one answer per session is possible.
The purpose is to be able to compare / analyze answers to the same questions (by different users or by the same users at different times, i.e. with different sessions).
A template, being a collection of chapters & questions, should not have to be replicated, if chapters and questions are the same.
(That would be necessary if Answer did not have a relationship to Session.)
Is the relationship from Answer back to Session the right strategy?
What else would you improve to simplify the model?
Thank you!
EDIT
Follow-up clarification:
The Answer is not static (e.g. "right" answer, "solution"), but some text the user inputs. It is more like a "questionnaire" than a "quiz". The answer has quantitative attributes that can be analyzed.
As stated, one question can have only one answer within a session. Because questions can indirectly belong to more than one session (via (NSSet*) question.chapter.template.sessions), they could have more than one answers and thus need a to-many relationship.
The typical scenario: User starts a new session with a certain template and fills out the answers. Then he can look at the analysis of the results and compare those with the results of other sessions that use the same template.
EDIT 2
The snapshot of the data model including attributes
honestly, this is what I would do instead of your structure, but I don't know what the purpose of the each entity because I'm not able to find out from their simple names.
this is just an idea to resolve the loop.
you can still reach all templates and all answers from the session, not directly but it does not make your life much harder.
UPDATE:
at the first and second sight, for me, it seems the Session entity is just an extra entity only here. honestly you would not need it, if you concatenate with the Template (aka Questionnaire) entity.
you have to add a many-to-many relationship between the Template and User (you can do it, don't worry about it). using this way, from each template you can reach all answers as well, and you won't have any loop.
Despite the really helpful effort by the part of #holex - the best way still seems to be to stick with my design. The simplifications I had hoped for have not materialized.
Related
I have a situation as described in the ExtbaseFluid book:
I would like to store information in the intermediate table which is not recommended at all.
Here is a cite from the warning box of the above linked book chapter:
Do not store data in the Intermediate Table that concern the Domain. Though TYPO3 supports this (especially in combination with Inline Relational Record Editing (IRRE) but this is always a sign that further improvements can be made to your Domain Model. Intermediate Tables are and should always be tools for storing relationships and nothing else.
Let’s say you want to store a CD with its containing music tracks: CD -- m:n (Intermediate Table) -- Song. The track number may be stored in a field of the Intermediate Table. However, the track should be stored as a separate domain object, and the connection be realized as CD -- 1:n -- Track -- n:1 -- Song.
So I want not to do what is not recommended. But thinking about the workflow for the editor that results of the recommended solution rises a few question for me.
To stay with this example I would need the following tables:
tx_extname_domain_model_cd
tx_extname_domain_model_cd_track_mm
tx_extname_domain_model_track (which holds the track number)
tx_extname_domain_model_track_song_mm
tx_extname_domain_model_song
From what I know this would end in the situation that the editor would need to create following records:
one record for the cd
one record for the song
now the editor can create one record for the track.
There the track number is added.
Furthermore the cd record needs to be assigned as well as the song.
So here are my questions:
I guess this workflow cannot be improved with some (to me unknown) TCA setup?
An editor cannot directly reach the song when the cd record is opened?
Instead first she / he has to open the track record and can from there navigate to the song?
Is it really that bad to store data in the intermediate table? The TYPO3 table sys_file_reference does the same!? But I wonder how those data could be shown (because IRRE is not possible because it shall only be used for 1:n relations (source).
The question you have to ask yourself is: Do I want to do coding by the book, or do I want to create a pragmatic approach to solve a customer's problem?
In this specific case the additional problem is, that the people who originally invented Extbase had a quite sophisticated and academic approach, but when it comes to a pragmatic use and performance, they were blocked by their own rules and stuck with coding by the book.
Especially this example and the warning message shows a way of thinking that was one of the reasons, why I never actually used Extbase but went for Core-API methods to create performant and pragmatic queries to get the desired result sets. Now that we've got Doctrine under the hood, this works like a charm even with quite exotic DB flavors.
Of course intermediate tables are a good idea and of course those intermediate tables can and should be enriched with additional data fields, that do not require a 3rd, 4th or nth table to store i.e. a simple set of dropdown options, since this can easily be handled with attributes configured in TCA, as it is shown here: https://docs.typo3.org/m/typo3/reference-tca/master/en-us/ColumnsConfig/Type/Inline/Examples.html
sys_file_reference is the most prominent example since it provides exactly that kind of additional information that should not be pumped into additional tables - and guess what, the TYPO3 core does not make use of a single line of Extbase code to deal with that data or almost any other data of the core tables.
To answer your last question: Take a look at the good old IRRE Tutorial to get a clue how to do m:n connections with intermediate inline tables.
https://docs.typo3.org/typo3cms/extensions/irre_tutorial/0.4.0/Manual/Index.html#intermediate-tables-for-m-n-relations
Depends on the issue, sometimes the intermediate table is an entity, sometimes not. In this example the intermediate table is the track, which would contain: [uid, cd, song, track_no, ... (whatever else needed to define the track)]
Be carefull when you define your data, that you do not make it too advanced.
Given there is a one to many relationship between users and comments, and all ids are provided to be unique;
what are the considerations between naming the operation as:
DELETE /users/{user_uuid}/comments/{comment_uuid}
or
DELETE /comments/{comment_uuid}?
In the former user_uuid is redundant as it's not needed to delete a comment. Is it worth keeping user_uuid just to make the urls looks RESTful?
Both work fine for well structured RESTful resource--long as the comment_uuid is indeed a uuid. Neither hint at the underlying implementation or strikes me as screaming this is an RPC service :)
Whatever you choose, rule #1... Keep it consistent.
That being said, I prefer the first one as it reinforces semantic information that this is a user comment. I can see that and know pretty much what I'm getting back, without making a request.
Comment is a bad one to show a counter case, because most comments are from users, but think about this... conceivably, you could have some other type of entity that leaves comments, imagine registering bots in your system /bot/{bot_uuid},
Now if you go with just /comment you did you just delete a user or bot comment?
Compare this as you're scanning code vs /bot/{bot_uuid}/comment/{comment_uuid}. The more verbose is a lot clearer IMOP.
Finally, if someone provides a get request for a specific comment /users/{user_uuid}/comments/{comment_uuid} I know the URL for the user, just drop the omment part. Sure, most might guess, /user/{user_uuid}, but like I said, user and comment are bad examples, as you get more non-typical resource name it becomes less obvious. The thing is if you're alway's explicit, you don't have to worry when the resources looks like these:
/widget/{widget_uuid}/contrawidget/{co_uuid}/parts/{part_uuid}
/spaceframe/{spaceframe_uuid}/parts/{part_uuid}
Now would you just do parts:
/parts/{part_uuid}
probably nots as it could be confusing to the consumer
Is it worth keeping user_uuid just to make the urls looks RESTful?
No. The business value that you get from making the identifiers look RESTful is indistinguishable from zero.
You might do it for other reasons: URI design is primarily about making things easier for humans. As far as the machines are concerned, all of the URI could just be UUIDS with no other hints.
That said, there is something important to consider....
/users/{user_uuid}/comments/{comment_uuid}
/comments/{comment_uuid}
These are different identifiers; therefore, as far as the clients are concerned, they are different resources. This means that, as far as clients are concerned, they are cached separately. Invalidating one does not invalidate the other.
(Of course, other clients, unaware that the DELETE happened, will continue using cached copies of both resources. Cache invalidation is one of the two hard problems).
I think that what your question is a design question and not a RESTful question as #ray said, and like for all design question the answer is... depends.
I prefer the first one also, because the comment (as I understand a comment) could not exist without a user.
But for this kind of questions I use the Entity-Control-Boundary Pattern (EBC) it basically propose a form to interact with your application in the context of certain entities, not using all the entities of the system, just the key ones, I generally use this as my rule to identify the paths that make more sense.
This question is about why I would use the above keywords. I've found plenty of MSDN pages that explain how. I'm looking for the why.
What query would I be trying to write that means I need them? I ask because the examples I have found appear to be achievable in other ways...
To try and figure it out myself, I created a very simple entity model using the Employee and EmployeePayHistory tables from the AdventureWorks database.
One example I saw online demonstrated something similar to the following Entity SQL:
SELECT VALUE
DEREF(CREATEREF(AdventureWorksEntities3.Employee, row(h.EmployeeID))).HireDate
FROM
AdventureWorksEntities3.EmployeePayHistory as h
This seems to pull back the HireDate without having to specify a join?
Why is this better than the SQL below (that appears to do exactly the same thing)?
SELECT VALUE
h.Employee.HireDate
FROM
AdventureWorksEntities3.EmployeePayHistory as h
Looking at the above two statements, I can't work out what extra the CREATEREF, DEREF bit is adding since I appear to be able to get at what I want without them.
I'm assuming I have just not found the scenarios that demostrate the purpose. I'm assuming there are scenarios where using these keywords is either simpler or is the only way to accomplish the required result.
What I can't find is the scenarios....
Can anyone fill in the gap? I don't need entire sets of SQL. I just need a starting point to play with i.e. a brief description of a scenario or two... I can expand on that myself.
Look at this post
One of the benefits of references is that it can be thought as a ‘lightweight’ entity in which we don’t need to spend resources in creating and maintaining the full entity state/values until it is really necessary. Once you have a ref to an entity, you can dereference it by using DEREF expression or by just invoking a property of the entity
TL;DR - REF/DEREF are similar to C++ pointers. It they are references to persisted entities (not entities which have not be saved to a data source).
Why would you use such a thing?: A reference to an entity uses less memory than having the DEFEF'ed (or expanded; or filled; or instantiated) entity. This may come in handy if you have a bunch of records that have image information and image data (4GB Files stored in the database). If you didn't use a REF, and you pulled back 10 of these entities just to get the image meta-data, then you'd quickly fill up your memory.
I know, I know. It'd be easier just to pull back the metadata in your query, but then you lose the point of what REF is good for :-D
I like knockoutjs, the sooner we get rid of coding directly toward the DOM the better. I'm having trouble understanding how I would do something which I'm going to explain in terms of a question/answer site. (This is probably a general MVC/MVVM question)
In my data model I have a question[id, description] and answer[id, question_id, text]. The browser requests a list of questions which is bound to a tbody, one column will display the question description, while the other should be bound to an answer textbox.
One obvious way of doing this is to have a QuestionAnswer[question_id, answer_id, question_descrition, answer_text] model. Ideally I'd like to keep them separate to minimize transformation when sending/receiving/storing, if there isn't some way of keeping them separate then I have the following question:
Where is the ideal place to create the QuestionAnswer model ? My bet is that by convention its created on the server.
If there is such an example somewhere please point me to it, otherwise I think it would make a good example.
Please help me wrap my head around this, Thanks!
What you could do is to create the combined model on the server, serialize it to json and then use the mapping plugin to add the serialized list to the view model.
I'm doing that here only it isn't a combined model, but shouldn't make any difference. Especially since it seems like your relation is one-to-one.
If you need to create an "object" in your view model, you can use the mapping definition to do so, like I do here.
I use C# to build my model on the server, but I guess you can use whatever you are comfortable with.
The cool thing with the mapping plugin is that it adds the data to the view model so that you can focus on behaviour.
Ok,
I'v gathered my thoughts on what my question is actually asking.
To do data binding on the client side you obviously need your data model there as well. I was conflicted on what I needed to send over and at what time.
To continue with the Question/Answer site idea: Sending down a list of answers each of which have a question in them is what should be done. That way you can bind to the answer list and simply bind the question description of each answer to the first table column.
If later I want to make a question editor I would potentially send a complete different data structure down and not reuse the Answer has a Question structure previously used.
I thought there might be a way of sending down a more complex data structure that references itself. Which apparently is possible in JSon with some extra libraries.
These day I work with a database that have this style of relationship then I've been very confused with it. This database is in a very large web app & have worked well for 10 years then I wonder whether this design is good in someway? or in which situations I should implement it?
Welcome any idea!
There is nothing wrong in my opinion. You can have, for example, in a personal_data table a place_of_birth field and a place_of_living field both referring to a cities table. By the way you should post a more meaningful example to have a more precise answer.