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ninjaef wrote: this place is a joke
Well only because of the questions that get posted. 
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nope, by the incompetent replies that , well , have zero value. Complete waste of time replying. Why bother. Annoy someone else instead.
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Oh no, it's much more fun annoying people who think that they own these forums, and we are their slaves.
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Yes, indeed i have had great fun in doing so.
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So two people have completely "failed to grasp the nettle", and you assume the problem MUST be that they're idiots, or that this site is "a joke".
The failure to communicate couldn't possibly be a problem with your question, could it? 
Back away from the computer. Take several deep breaths. Go and do something relaxing for a while. Then come back without the attitude, and explain your question in more detail. If someone doesn't seem to understand, then don't fly off the handle; explain it in yet more detail. Keep elaborating until either they understand, or the solution jumps out at you.
"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer
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If I said: "as other pointed out", it would also sound funny and you would probably make hay of that too.
"(I) am amazed to see myself here rather than there ... now rather than then".
― Blaise Pascal
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The problem here is that Pythonic refers to a using the language in such a way that it is clear, maintanable and concise. That's not really an aspect of how you break down the design of your architecture; rather it's a case of, when you have your architectural domain designed, how do you use the language following Pythonic principles and, more importantly, how do you structure your code so that others can use yours in a Pythonic way. I really do think you are conflating two separate problems in this question.
This space for rent
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I want to allow the user to create their own lookup values that would be populated in a combo box. For example, an account's Statuses might be New, In Progress, or Closed. The use can Add, Edit, and Remove these from the lookup table at any time.
For this, I have a lookup table with Id, Caption, and Category. Other tables might have a StatusId that has an FK to Lookups.Id.
So, some questions:
1) Before they can remove a status I would like, to ensure that the Id isn't in use. I could query each table that it the target of the FK. Is there a simpler, more manageable way?
2) I would like to take action when the user selected the Closed option. How do I know for sure that this particular Lookup item was selected? Since it can be renamed I can't rely on the caption. I could have some other column in the table with some identifier in it and check that identifier in code, but that couples the code to a specific data item.
Thanks
If it's not broken, fix it until it is.
Everything makes sense in someone's mind.
Ya can't fix stupid.
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Oh you are in for a world of hurt going down this particular rabbit hole.
Most/some lookup tables have a consequence in your code - how do you associate a new status with an action.
A generic lookup table simplifies the maintenance until you find a lookup that does not fit your structure (this always happens 2/3 through the project). I now have a table for each lookup type, I decide which ones can be edited. The delete procedure has to deal with FK and usage issues.
I recently got called a dinosaur by an out source architect for insisting on this structure, they then went down the generic path. I got a laugh when they ended up with a 3 table generic structure that was so complex the developers got lost trying to maintain it. F***ing whipper snappers.
Never underestimate the power of human stupidity
RAH
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Don't "delete", use "expiry dates" for your lookup entries; don't show "expired" ones in the maintenance views except in "browse" mode.
Insures referential integrity ... even "years" later.
"(I) am amazed to see myself here rather than there ... now rather than then".
― Blaise Pascal
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I never delete. I always use delete date. That's what I mean by delete.
If it's not broken, fix it until it is.
Everything makes sense in someone's mind.
Ya can't fix stupid.
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Quote: Before they can remove a status I would like, to ensure that the Id isn't in use
Why?
Or is "remove" not the same as "delete"?
"(I) am amazed to see myself here rather than there ... now rather than then".
― Blaise Pascal
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True. I don't need to remove it
If it's not broken, fix it until it is.
Everything makes sense in someone's mind.
Ya can't fix stupid.
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I noticed last week that the latest version of the Node Package Manager automatically audits your installation, checking installed versions against the data base of documented vulnerabilities in the NPM Registry. It delivers a very nice report, complete with instructions for automatically fixing many vulnerabilities by upgrading the affected packages. Other package managers (e. g., NuGet for Microsoft .NET, Composer for PHP, PIP for Python, PPM for Perl, would do well to implement such a feature, and probably will soon.
David A. Gray
Delivering Solutions for the Ages, One Problem at a Time
Interpreting the Fundamental Principle of Tabular Reporting
modified 5-Jun-18 17:37pm.
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The Data Mapper pattern is an effective way to decouple the domain model from whatever data storage system the application uses. However, one thing I noticed about it is that it does not explain how and when the data mapper should be notified that it needs to update the data.
I propose that the domain object notifies the data mapper (and, possibly any other objects that are interested) when one of its fields/properties changes via an event (I use C#, which supports events and properties and have the code to publish the event in the property's getter). The data mapper can then do whatever it sees fit to do with this information. Using events also inverts the dependency between the domain object and its data mapper.
Whenever a domain object is created in memory (either read from data or completely new), a data mapper should subscribe to its relevant events. There could be one data mapper per domain object or one per type of domain object. Additionally, the logic for creating, reading, and deleting domain objects need not be in the same data mapper that handles updates.
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I don't think that update notifications are in the scope of the pattern. The Data mapper describes how persistence is handled, not when or why.
Other patterns, such as Repository and Unit of Work, can be leveraged in conjunction with a Data Mapper in order to provide the actual update logic. This is the SOP for current MVC.NET applications with EF.
"There are three kinds of lies: lies, damned lies and statistics."
- Benjamin Disraeli
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What I'm describing is supposed to be a new "version" of the data mapper pattern.
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Yeah, I got that. I just disagree with your premise. 
"There are three kinds of lies: lies, damned lies and statistics."
- Benjamin Disraeli
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That's fine.
From what I read of the data mapper pattern, all it really says is separate the data logic (CRUD) from the domain object stuff (i.e. don't use the active record pattern), which, while lacking in detail is great advice.
I saw that you mentioned the unit of work and repository patterns in your previous post and took a quick look at them. I don't see how they directly relate to updating domain objects. From what I saw, it seems like the controller or something has to tell the unit of work class to update a domain object. How/where do you deal with determining how/when to update domain objects?
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The Repository pattern is 100% about updating domain objects against a persistence store. UoW is about making those updates atomic in nature. The Repository is purpose-structured to use the Data Mapper pattern; as the entire purpose of the pattern is to define a persistence touchstone for model classes (AKA domain objects).
You can do it procedurally in a more functional/workflow model (such as the controller queuing and update) or, as you're advocating, through an event driven paradigm. In desktop applications I like to hook updates to ViewModels through INotifyPropertyChanged, for instance, so that user updates to relevant objects wrapped in ViewModels will update when the user updates them.
Event-driven updates are basically a must in any asynchronous approach, but I would argue that they need to be hooked to model handling logic rather than the models themselves.
"There are three kinds of lies: lies, damned lies and statistics."
- Benjamin Disraeli
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Paramecium13 wrote: I propose
To whom?
I like the idea, but it will probably get buried under a lot of other posts in the forum. Given the paragraphs in your post, I am convinced that you can write an article about the subject; ideally, you would also explain the Data-Mapper Pattern itself, include a simple example, and add your proposed change. Aw, and pictures if possible, people love pictures
The results will then also show up higher on Google, as articles seem to be favored over forum-posts. It would also change the audience from "people scanning the forum" to "people watching the article queue for new stuff to learn". If enough people agree with your article, then it may become "the" way to do it.
Bastard Programmer from Hell 
If you can't read my code, try converting it here[^]
"If you just follow the bacon Eddy, wherever it leads you, then you won't have to think about politics." -- Some Bell.
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Yeah. I might write an article. I figured I'd post it here first to see what people think.
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Recognizing the growing number of applications that used two or more programming languages in their implementation, I extended the Reddick VBA Naming Conventions to cover virtually any programming language in 2006, naming the extended conventions the Reddick-Gray Unified Naming Conventions. Fast forward 12 years, and a Scottish musician living in the south of France finds a copy, and writes to me with some great questions and an excellent critique. The result is version 2.10 of the conventions, now online [here].
The work is based on Hungarian Notation because I believe they are as useful today as they were when Charles Simonyi published his paper. Though some claim that modern integrated development environments render the Hungarian prefixes moot. I think not, for the following reasons.
- Code Reviews: Copies of code that are dropped into email messages and distributed for code reviews lose the connection to the IDE tools that let you see the types of the variables.
- Git Repositories: Copies of code that find their way into a Git repository lose their connection to the IDE tools that let you see the types of the variables.
- Bulletin Boards: Code posted on a bulletin board, such as the Code Project question forums and Stack Overflow are deprived of their type hints.
- Too Many Lines to Fit on Screen: Frequently, it is impractical to keep every routine short enough to fit on one screen. Even if you adhere to the accepted practice of declaring variables close to their first use, all it takes is one long
switch block to hide the declaration.
I rest my case.
David A. Gray
Delivering Solutions for the Ages, One Problem at a Time
Interpreting the Fundamental Principle of Tabular Reporting
modified 29-May-18 15:00pm.
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The first obvious question would be whether it is based on System or Apps hungarian. After a bit reading, looks like Systems Hungarian.
X DO NOT use Hungarian notation. Hugarian notation – it’s my turn now – Larry Osterman's WebLog[^] - where "sz" is a prefix for a null-terminated string. How often did you have to convey in C# or VBA-code that a string is null-terminated instead of Pascal-style?
David A. Gray wrote: Frequently, it is impractical to keep every routine short enough to fit on one screen.
No, it is not. Any example from MSDN fits on a printed fixed-font 80 column A4 paper. Anything longer probably has more than a single responsibility and is a candidate for refactoring.
Bastard Programmer from Hell
If you can't read my code, try converting it here[^]
"If you just follow the bacon Eddy, wherever it leads you, then you won't have to think about politics." -- Some Bell.
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Eddy Vluggen wrote: The first obvious question would be whether it is based on System or Apps hungarian. After a bit reading, looks like Systems Hungarian.
X DO NOT use Hungarian notation. Hugarian notation – it’s my turn now – Larry Osterman's WebLog[^] - where "sz" is a prefix for a null-terminated string. How often did you have to convey in C# or VBA-code that a string is null-terminated instead of Pascal-style?
Just because Microsoft says it's so doesn't make it so. IMO, this advice is ill-conceived for reasons that I gave in my original post. As for distinguishing null-terminated from counted strings, I'm sure there's an edge case somewhere, but it's never been a concern to me that couldn't be addressed by other means, such as passing the length of a counted string, or zero for a null terminated string of unknown length.
Eddy Vluggen wrote: David A. Gray wrote: Frequently, it is impractical to keep every routine short enough to fit on one screen.
No, it is not. Any example from MSDN fits on a printed fixed-font 80 column A4 paper. Anything longer probably has more than a single responsibility and is a candidate for refactoring.
Citing examples from MSDN is an insufficient defense. I live in a real world in which not every routine can or should be that short. Moreover, what happens when your view of the source code is constrained by the many other windows of an interactive debugger?
David A. Gray
Delivering Solutions for the Ages, One Problem at a Time
Interpreting the Fundamental Principle of Tabular Reporting
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