I am planning to use JPA Entities to create my data model. As part of the design , we have been asked to document the data model and keep them updated. I was asked to used plantUml to create the Database model, but I would like to see how to get started on converting the JPA Entity--> plantuml macro code --> Data model. Seeking out help to see how I can tackle this request
You can build your model Structurizr and then export them to PlantUML.
https://github.com/structurizr/java-extensions/blob/master/docs/plantuml.md
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I am developing a SPA using Angular-Breeze-WebAPI-EntityFramework.
Now Breeze uses the Entity Framework metadata information to create it's own Breeze models. We use this in our application for Breeze validation.
So far, it's all been nice and easy. Now we are having to create a search page (say for querying customers). The search can be by Customer.Name or by Product.Id (which would return a list of customers who have bought that product). The result is a ng-repeater, which displays Customer.Name, Order.LastPlaced etc.
if you are getting confused by the tables and columns, forget that. What I am only trying to get to is that, both the search object and the result object are not 1:1 with Entity tables (or objects). So obviously I feel the need to create a custom object (one for the search and one for the results). My question primarily is where and how do I create that object?
If I create it at the data layer, Breeze would have no idea of the metadata for each of the properties (since it uses EF for that).
I obviously can't create just a JavaScript object, since I will have to query the database (using EF) to search and populate the object.
So where does one create such a custom object (traversing multiple tables) such that Breeze still can figure out the metadata and perform validation and such when the need arises?
Thank you all.
You can create metadata on the client for types that the server either doesn't know about or doesn't have the schema for. See http://www.breezejs.com/documentation/metadata-by-hand.
I'm working with a legacy database that I can't easily create an entity model over because it uses extension tables with what is effectively composite keys and EF only supports single column keys for mapping one entity to multiple tables.
So, what I've decided to do is create updatable views (with INSTEAD OF triggers to handle CRUD operations) over the top of the legacy tables (which cannot be touched) and then have my entity model (either using EF or DevExpress XPO) built on top of the database views. This will also allow me to do stuff like easily add sub-queries in the select clause to retrieve child counts on parent records when retrieving a list of parent records in a single query.
However, I don't particularly want to manually write the SQL for all the views and triggers so I thought I'd use data model defined in the .EDMX file and t4 templates to help me generate the bulk of the T-SQL needed to create the views and the triggers. I thought there would be some template that I could use as the basis for doing this, but seems that's not so easy to find.
Can someone please suggest a t4 template that I could use as the basis where mappings are being retrieved from the .EDMX. Alternatively can anyone advise how to use the StorageMappingItemCollection to retrieve the mapping information from the EDMX file. I know a few people have said that apparently you can't use it or that they just use Linq to Xml, but I would have thought it should certainly be possible to use the StorageMappingItemCollection class as a strongly typed class to access this data.
Any examples of how I could use StorageMappingItemCollection to access mapping info would be very helpful. Thanks.
See http://brewdawg.github.io/Tiraggo.Edmx/ you can install it via NuGet within Visual Studio and it serves up all of the metadata from your EDMX files that Microsoft hides from you, very simple, works great.
I am currently writing a WCF data service that is meant to extract data from any database in a predefined standard structure.
I was thinking of using POCO entities. I can design my entities on EF designer and generate the POCO classes from it but the bit I struggling to understand is how to write data access layer and inject it into the DBContext.
So for each different database, I'll have a data access layer that will retrieve data from a database or even an xml file and map the data to my POCO entities.
I am not sure if this is achievable at all.
The POCO classes will be my standard structure to expose to the world.
I can't see anywhere to write custom sql queries to extract data from a DB and then set the data in the POCO classes. The POCO classes do not match any of the database tables so I explicitly need to map database fields to the POCO classes but I am not sure how to do this in Entity Framework using POCO.
I believe POCO is the write option but struggling on the data access layer and mappings from database to POCO classes.
All the samples I have seen talk about connecting the EF to an existing database directly. Meaning the EF structure has to match the structure of the database. What I want is a single EF/POCO structure that can retrieve data from multiple databases. These databases do not have the same structure but I need to manually retrieve data from these databases and transform it into the POCO classes structures. I do not necessarily want to get data from multiple databases at once but from a single DB but want to use the same model for any database - So I guess I have to write a custom DAL for each database which gets the data from a DB and transform the data into the POCO model structure.
I would really appreciate if anyone could help me.
By the way I am new to EF so please be patient.
Have you followed this tutorial which shows you how to create model classes from a DB and query against them?
Also here is a great tutorial on using EF code-first, in which you build your POCO classes first, and it generates the DB for you. Great read :).
Trying to understand Entity Framework. My approach is database first. However I would like to define other entites in the model that is closer to my business objects. I guess I could write queries in the db and include them in the model. But I would also like to define entirely new entities in the model though they would be based on underlying tables in the db. How do I do that - does anyone know a tutorial?
Regards
Bjørn
db Oldtimer, EF Newbie
Database first means that you have existing database and you can either create model by updating from database or manually. You can use wizard to create initial model and modify it manually to define new entities but you must not use update from database any more or some of your changes will be deleted. Also your custom modifications must follow EF mapping rules (for example it is not directly possible to map multiple entities to the same table except some more advanced mapping scenarios like splitting and inheritance) and some of them (custom queries) must be done directly in EDMX source (XML) because designer doesn't support them - this requires more complex knowledge of EF mapping and it will be definitely hard for newbie.
You can check specification of that XML. For entities mapped to custom queries you will have to use DefiningQuery element in SSDL part of EDMX.
The method - Entity Framework Code-First - looks good. But its very difficult to create all the classes for a large database.
Is there any easy way to generate the Entity Framework Code-First classes?
You can use the recently released Entity Framework Power Tools CTP1. The tool gives you the ability to reverse engineer code first, meaning the Database will be mapped to Code.
Note that all tables in your large database will be mapped. There currently is no way to choose which tables will be mapped to code. Reading through the comments, this feature will most likely be implemented in a future release.
The point of EF Code-First is that you define your domain model in code, then your user-interface and database can be easily generated from that domain model. This has a number of advantages including reducing the amount of tedious code which needs to be written, and helping to ensure your database, your domain model, and your UI match each other.
However, at some point you are going to have to write your domain model - there's no way that can be "generated" (by which I assume you mean computer-generated) as it is personal to your application.
If I've misunderstood your question, please leave a comment and I'll update my answer.
If you want to use the code-first model, but already have an existing database, you can use the Entity Framework Power Tools to generate classes.
If you're reading this after May/2012, the above tool may be out of beta!
No there is no way to generate classes for you if you are using code-first. Code first means that there is no model and no database so you can't generate classes unless you have some upfront design in any case system (UML) which will autogenerate code for you. Simply generating classes without any input about how they should look like sounds like AI from Sci-fi, doesn't it?
If you already have databse you are not using code first but database first. In such case you can have your classes generated.
Check out the link below. It's a program that will generate POCO classes from your databases. I think that's what you're looking for.
http://msormcodegen.codeplex.com/
Generate the code from the database first using database first generation and then modify the resulting code to start your code first version