I need to query the EA database in order to discover the visibility status of a class attribute.
I've been snooping around but could not find the table where this information is stored.
Any help will be appreciated.
This is a case of inconsistent naming in EA. The property that's displayed as the attribute's Scope in the GUI is referred to as Attribute.Visibility in the API, and stored in t_attribute.Scope in the database.
Similarly, the same property of an element is displayed as Scope in the GUI, referred to as Element.Visibility in the API and stored in t_object.Scope in the database. There is a column t_object.Visibility, but it appears to be unused.
Related
I'm on Enterprise Architect 14. I have a component diagram containing an interface User and two classes Employee and Customer, which both realize interface User.
Furthermore I created two instances, one of each class and specified the values of the attributes via Features & Properties > Set Run State....
Next I created a component with 2 attributes, one of type Employee and one of type Customer. Then I created an instance of the component.
Now I would like to set run state of the component instance by assigning ArbitraryUser to the Employee attribute and ArbitraryCustomer to the Customer attribute of the component instance. According documentation this should be possible (see here).
At run-time, an Object instance can have specific values for its attributes, or exist in a particular state. To model the varying behavior of Objects at run-time, use instance values selected from the 'Select ' dialog and run-time states or run-states.
However I could not figure out how to do so. Can someone help me?
AFAIK that is not possible.
I'm not sure what the quote from the help really means, but I've only ever been able to type a value for the run state.
An partial alternative would be to use associations rather than attributes to model such relations. Then you can create a link as an instance of the association to relate instances of Employee or Customer with instances of a ArbitraryComponent.
This solution doesn't work for datatypes, but it seems a bit far fetched to start modelling instances of datatypes.
We would like to create an OData REST API. Our data model is such that each customer has their own database. All database objects have the same definition across all customer databases, with the exception of a single table.
The customer specific table we will call Contact. When a customer adds a column the system creates a column with a standardised name with a definition translated from options selected by the user in the UI. The user only refers to the column data by a field name they have specified to enable the user to be able to generate friendly queries.
It seems to me that the following approaches could be used to enable OData for the model described:
1) Create an OData open type to cater for the dynamic properties. This has the disadvantage of user requests for a customer not providing an indication of the dynamic properties that can be queried against. Even though they will be known for the user (via token authentication). Also, because dynamic properties are a dictionary, some data pivoting and inefficient query writing would be required. Not sure how to implement the IQueryable handling of query options for the dynamic properties to enable our own custom field querying.
2) Create a POCO class with e.g. 50 properties; CustomField1, CustomField2... Then somehow control which fields are exposed for use in OData calls. We would then include a separate API call to expose the custom field mapping. E.g. custom field friendly name of MobileNumber = CustomField12.
3) At runtime, check to see if column definitions of table changed since last check. If have, generate class specific to customer using CodeDom and register it with OData. Aiming for a unique URL for each customer. E.g. http://domain.name/{customer guid}/odata
I think the ideal for us is option 2. However, the fact the CustomField1 could be an underlying SQL data type of nvarchar, int, decimal, datetime, etc, there are added complications.
Has anyone a working example of how to achieve what has been described, satisfactorily?
Thanks in advance for any help.
Rik
We have run into a similar situation but with our entire dataset being unknown until runtime. Using the ODataConventionModelBuilder and EdmModel classes, you can add properties dynamically to the model at runtime.
I'm not sure whether you will have to manually add all of the properties for this object type even though only some of them are unknown or whether you can add your main object and then add your dynamic ones afterwards, but I guess either would be workable.
If you can get hold of which type of user it is on the server, you could then add only the properties that you are interested in (like option 3 but not having to CodeDom).
There is an example of this kind of untyped OData server in the OData samples here that should get you started: https://github.com/OData/ODataSamples/tree/master/WebApi/v4/ODataUntypedSample
The research we carried out actually posed Option 1 as the most suitable approach for some operations. i.e. Create an SQL view that unpivots the data in a table to a key/value pair of column name/column value for each column in the table. This was suitable for queries returning small datasets. This was far less effort than Option 3 and less confusing for the user than Option 2. The unpivot query converted the field values to nvarchar (string) values and thus meant that filtering in the UI by column value data types was not simple to achieve. (If we decide to implement this ability, I believe this can be achieved by creating a custom attribute that derives from EnablQueryAttribute, marking the controller action with it and manipulate the IQueryable before execution).
However, we wanted to expose a /Contacts/Export endpoint that when called would output the columns from a table with a fixed schema joined on a table with a client specific schema and output to a CSV file. All the while utilising the OData supported filter syntax. One of our customer databases has more than 12 million rows of data and is made up of approximately 30 columns.
To achieve this it looks like our best bet would have been to work with the Microsoft.OData.Core.UriParser.UriQueryExpressionParser class, unfortunately Microsoft in their wisdom have declared this as internal, as well as many of it's dependants.
Walking an abstract syntax tree built from OData supported query options and applying our own visitor to each node to build some dynamic Linq query/SQL seems like a possible solution.
For the time-being we will simply implement a cut-down set of supported $filter criteria without the support for grouping parenthesis.
It says here:
The definition of an edge label, property key, or vertex label cannot
be changed once its committed into the graph.
In contrast SQL Server, which is what I'd normally use, doesn't have a problem with, say, changing the type of a field or the cardinality of a relationship.
This isn't even in the Temporary Limitations section of that web page.
Why is this limitation here and what am I supposed to do when I make a mistake when defining a type? Delete the whole database and import all the data into a new one?
So I'm just learning Cache, and have a question about tables, classes and globals, what's the difference?
I'm doing the tutorial and it seems like, since this is an object-orientated DB that a class is a table and vice versa. So if I create a class and make it persistent with properties, I can use SQL to query it. Is this true? What's a global then?
Reason I ask is because I'm using Management portal for one of our Cache applications and although I can see a table in WinSQL and Documatic, that same table doesn't seem to exist in the class explorer (Under management portal)... can't figure it out, is it hidden? Is there a command to see class def'ns in terminal??
thanks!
In Caché, classes are tables and tables are classes. You can choose when you want to use SQL access and when you want to use Object Oriented access.
Globals are the sparse multidimensional arrays which sit as storage beneath the class/table. Look at the storage definition at the end of your class to see the actual globals that your persistent class is stored in (e.g. ^Sample.PersonD)
By default, class names are projected as table names, but there are some rules which apply in order to ensure that the table names comply with SQL standards:
if you have a class that is a couple of packages deep (e.g. MyApp.Data.Person) then all but the last "." will be replaced by "_" in the table name (e.g. MyApp_Data.Person would be the table name)
You can't use reserved SQL keywords in table names, so if you make something in the User package for example (class: User.Person) then Caché will change the Package name (e.g. SQLUser.Person would be the name of the table)
I suggest you refer to http://docs.intersystems.com/cache20141/csp/docbook/DocBook.UI.Page.cls?KEY=GORIENT_ch_persistence for more detail
Our company is in the middle of evaluating a couple of different ORMs and we are currently looking at the EF4 side of things.
I have a small question that I hope someone here can answer...
In our generated EntityDataModel.Designer.cs file all our Entity classes (and the properties within them) have a ///summary with the sentence "No Metadata Documentation available".
Is there any way to have these picked up from the Description Property on the columns from SQL Server?
I can see there is a documentation property within the edmx file but they are all blank.
Obviously its not a deal breaker in our decision - but it would be nice.
Thanks for any advice
Aaron.
Yes, documentation properties are blank in EDMX because you must fill them yourselves. EF doesn't load columns descriptions defined in SQL Server.
These columns descriptions are stored in sys.extended_properties and have MS_Description as a name. Theoretically you can modify T4 template (EFv4) to load descriptions for columns and create comments but it would be a lot of work to do. You will have to:
for each scalar property you will have to search metadata to get column and table name and query DB to get a description
That is a lot of work and having T4 template opening connection to database is very uncommon.