PowerAMC/PowerDesigner allows you to create "graphical synonyms" of underlying entities allowing you to place the same entity twice (or more) on a diagram. Each is an instance of the same entity. This is great to pretty-up diagrams when, somehow, an entity must be linked to two others that happen to be on opposite ends of the diagram.
Is there a way to do this in Visio 2010 when using the database modeling template?
There are two ways of doing this:
Open the Table and Views panel (Database tab, Model Preferences, first tab, "when deleting an object from the diagram" should be on "Ask the user")
Drag and drop the existing table from that panel onto the diagram
This creates a duplicate of the logical entity and recreates all links (relations) to it. Not immediately useful to clean up the diagram but if you delete the extraneous links and say "No" when it asks if it should also delete the logical elements, then the links disappear visually but the foreign keys remain.
Second method:
Copy a table from the diagram (CTRL+C)
In the Home tab, choose to Paste, Special Paste and keep what should be the default mode: Visio diagram data
A copy of the table will appear but it won't be automatically linked to anything visually.
From both points, the duplicates on the diagram are both logically the same entity. This means that if you modify one, the other is also modified. If you link one to something, the other one is also logically linked (foreign keys will be listed in both, though only one may have the visual link).
Note: I'm using the French version of Visio so exact labels mentioned may be different in English. I tried translating to the best of my ability.
If you press the control key then click and drag an entity it will create a synonym.
I have yet to figure out how to remove a specific synonym without deleting all replicas of it.
Related
I see that Magic Draw supports both graphical and tabular notations. However, I would like to know if they can be synchronized to one another or they only function separately. So, if I create a class diagram with the graphical editor, can I generate a table from it in MagicDraw? And whenever I make the changes to one editor, the changes to be reflected in the other editor?
Thank you!
The answer is complex.
First, diagrams are views of the model. Tables, as just another kind of diagrams, are therefore views of the model. In other words, changing an element in a table will change the element in any diagram it is displayed.
Now it gets complex - but how you use the tool can simplify the. You seemed to ask, can a table be synchronized with a table and a table with a diagram? A table can be based on a scope, a query, or by composition (drag an element onto the table or create on the table). Scope or query is is a lot better because they can be used to match the diagram or package where the diagram puts its data (by default, the package where the diagram is stored).
However, diagrams are intended to be expressions of the human for us humans. Thus the diagram does not automatically add elements if they were added in a table.
How do we square the circle? How do we add (or even detect) an element created on a diagram? There is a way to get a list of diagrams (https://community.nomagic.com/usage-in-diagram-displayed-in-generic-table-t5789.html ). Using a similar technique a rule could be created to warn about elements that are not on any diagram. It is still up to you to add the element to the diagram with this information at hand (or write a fancy plugin).
Is it possible to define navigation properties between Views in EF with code first? Please, note that I do not need any tool generating any code for me. I would like to know whether or not this can get done and the logic behind this.
Suppose you have a project in which you will only work with views. No data will be created, updated or deleted (at least by you). All you need to do is queries and all you have are views.
Suppose now a second scenario in which you can also have tables, but your purpose is only to visualize data (you will treat them as views). However, there is not always a foreign key referencing the primary key of the parent table in relationships.
My question is: Can I define navigation properties in these scenarios? Or do I have to relay on joins only?
Thanks!
I'm working on this myself. Everything I'm reading indicates you have to manually edit the .edmx files so that the views are considered tables and manually add the nativation properties yourself. Downside is if you resync against the database you have to repeat the process all over again.
Re:
https://social.msdn.microsoft.com/Forums/en-US/dcbdfe52-6ba7-4e75-94aa-51c88b57635c/adding-navigation-property-to-a-view?forum=adodotnetentityframework
I'm starting to use Master Data Services and I came across something strange. When I deploy the sample models and entities and afterwards go to the Master Data Manager website, I see under "System Administration" in the left column under the Model name a tree structure of entities.
However, when I created my own model and entity (+attributes), I couldn't find the entity under the model on the left side.
How can I fix this?
I suppose that is also why I get an "invalid entity" error message when trying to create members through the API.
I was able to fix this, although I'm not sure if it's really necessary to 'fix'.
When creating an entity, if you set "enable explicit hierarchies and collections" to "yes", the entity will be placed in the left-hand side tree view too.
I'm not sure if it's absolutely necessary to do so for at least one entity but it did help in my case.
Microsoft mentions the following about this ( http://technet.microsoft.com/en-us/library/ff487054.aspx ):
From the Enable explicit hierarchies and collections list, select one of the following options:
No. Select this option if you do not need to enable the entity for explicit hierarchies and collections. You can change this later if needed.
Yes. Select this option when you want to enable the entity for explicit hierarchies and collections. In the Explicit hierarchy name box, type a name. Optionally, select Mandatory hierarchy (all leaf members are included to make the explicit hierarchy a mandatory hierarchy.
Hope this helps.
The "strange" view is the Model View, and the entities you add from the left to the right side will be displayed in the "Explorer" view (inside the Explorer function, there is an Explorer menu as well).
So When I use the EF wizard right now and choose a view, it creates entities for every column in the view. How can I select entity generation for a specific few columns? I don't need all of them. Also, the DB schema changes often. Anything I can do to make sure it doesn't break my app?
You asked two questions, so this will be a two-part answer.
[Answer 1] There is no way to choose specific columns when generating the model via the wizard. However, once the model is generated, deleting a property will remove it (and its mapping) from the model. (Note that non-nullable columns will need to be surfaced as properties or you will get errors).
[Answer 2] In terms of responding to a schema which changes often, your best bet will to make sure you understand what is going on underneath your model. The EDMX contains 3 sections:
The "CSDL" - this is the "conceptual model" where your entity definitions are stored.
The "SSDL" - this is the "storage model" which keeps track of the state of your database.
The "MSDL" - this defines the mapping between the two.
When your DB schema changes and you run the "update model from database" wizard, your CSDL and SSDL may get out of sync. This is because the SSDL gets updated with the changes, but the CSDL will not (unless you are adding something new). Now, for the most part, this is a good thing, because it will not blow away any changes you've made, so your model will still work with your application logic. But you may see errors due to the changes in the SSDL.
There are a few ways to fix this:
If the changes to the database were relatively simple (added columns, renamed tables, etc) you might be able to simply redefine your mappings (using the "mapping details" window available in an entity's context menu). This does require some manual work. For instance, if new columns are showing up in the SSDL you'll need to add the corresponding properties yourself. You may even need to re-map an entire entity if your tables get renamed or too many mappings get dropped.
You can remove affected entities from the model and re-add them using the "update" wizard. This will blow-away any customizations you had made, and might cause some of your application logic to break. But if you are happier responding to database changes by updating your application's code than by mucking around with your entity mappings, this could be another option.
You can edit the XML manually. The designer isn't perfect for every situation, so if worse comes to worst you can always use the XML editor.
Hope that helps! There may not be a perfect solution, but it should get you most of the way there.
I have objects:
type A (Id, Name),
type B (AId, Description).
I want to make relation 1-to-1 (and create it 1-to-[0..1]). All works great exept deleting objects of type A. When I'm trying to delete some object from type A exception occurs.
A relationship is being added or deleted from an AssociationSet ‘...’. With cardinality constraints, a corresponding ‘...’ must also be added or deleted.
Im searched for solution (found editing CSDL for many-to-many), but nothing helps. There is also cascade action defined in the table in Database.
Any suggestions?
UPD: Thanks for answers.
Let's say more clear.
I don't want to implement inheretance betwen A and B
I try to fix problem by editing edmx file (like this http://codepolice.net/2008/12/16/cascade-delete-in-entity-framework/), but no luck. Seems it's only worked for one-to-many.
I just want to have 2 objects with one-to-one relation. For example, Order and OrderDetails. I expected automatic creating/deleting OrderDetails for every Order I have.
1:1 should give an exception if your deleting B right?
I think what you want is 0..1
Right click Add->associations.
under multiplicity:
On the left hand side choose One for A and 0 or 1 on the right for B.
I think you need this if you want an optional description object(B) for A.
You could also move B's fields into A and check not null for those fields right? That might be easier, then I think you could just use A's fields.
Also, I'm not a database designer by a long shot but, wouldn't you want the Data of A in A?
If for instance you had "Person" and his "Home", I would think those would be a good case for 1:1 (or 0..1 real world), because they themselves are 2 distinct objects that other objects can share independently.
Seems like the A_DataObjects just leads to an unnecessary join?
Old Answer below (not looking for inheritance, but leaving for someone else):
OK, I think I ran into this today. I think what you might want to do is define 2 classes as subclasses of a base class (entity). Right click and do add -> inheritance to get started. I didn't get this all working yet, but I think it involves specifying a field in the base, BaseType which can be used to key in on the derived classes.
http://mosesofegypt.net/post/Inheritance-and-Associations-with-Entity-Framework-Part-1.aspx
Note, there's a part 2 and 3 of this.
-David
One way to do this is to have a single entity that maps to 2 tables. See:
http://msdn.microsoft.com/en-us/library/bb896233.aspx
Visual EntityFramework tool doesn't recognize correctly 'on delete cascade' and creates incomplete xml mapping. You have to change edmx file (You can do it with notepad). Instructions here:
http://codepolice.net/2008/12/16/cascade-delete-in-entity-framework/
Worked for me.
Just make a one-to-many relationship, then by creating unique constraints on the foreign keys in the database you can force it to be 1:1. You can find a full tutorial about it here
(This uses Code-First)