I am looking to build the data access layer of my MVC5 application. In our project we are going for database first approach with stored procedures only as team is more conversant with SQL and would like to perform all CRUD operations via stored procedures.
I am looking for good examples that show the implementation of this approach. I want to see how the entities are mapped. As this would be stored procedures in the database getting mapped to classes in .net.
I think its time for your team to become "conversant" with EF if you are going to use it. Doing every single CRUD operation with stored procedures is not the path I would take. If the stored procedure is doing something simple as:
Get the company record with ID 1
Then I would not use stored procedure and use EF. For more complex operations, stored procedures can be used. Therefore, you and your team may want to have team work session to decide on when to use stored procedures and when not to. Once you have decided, the whole team should stick to that approach. If you need to change it, have another meeting and make sure everyone is in the know. It is important for everyone to follow the same pattern once the team has agreed to it.
How to use stored procedures with EF?
I would start with one test stored procedure to see how the whole thing works. Once you and your team know exactly how the process works with EF, then put together a design, conventions etc. and then the whole team should follow the same pattern.
Write a test stored procedure which returns a resulset.
Create the EDMX by connecting to your database from Visual Studio.
Add the stored procedure to your EDMX.
Use the model browser to add a Function Import. This will create a method in your context which you can call like any other method, but underneath it will call your stored procedure. Please see this answer for more on how to do this step.
Step 4 will create a class based on your stored procedure's resultset.
Note
You may need to set this flag to off, TEMPORARILY, for EF to create the complex type based on your stored procedure result set.
SET FMTONLY OFF
See this answer for more about the flag.
Related
I have a conceptual/architectural question I'd like to get some input on. Before I go into the details, I'd like to mention that I am well-aware of the arguments against putting application logic into the database, and the importance of maintaining abstraction and separation of concerns.
That being said, the application in question is a fairly simple one, in which performance is relatively more important than best practices. It is a new app, built with very modern technologies but on old school principles (stored procs, no ORM, etc).
I have a fairly complex "summary view" which is going to be driven by data provided by a stored procedure. Most of the elements of this view are going to have permission logic (not trivial, but nothing too complex) which will change both the appearance as well as the nature of the data based on the permissions of the currently logged in user (i.e. some data could be anonymized, other could be hidden, etc).
All data, as well as membership and ACL records, are stored in the same database.
So, the question is where to put the logic of applying user rights. The two options are:
1) Bring back all relevant data from the database into domain objects, then apply permissions in the middle-tier
2) Pass a user ID to the stored proc, and have it pass back an already prepared result to the middle-tier
At first look, conceptually, the no-brainer seems to be to throw it into the middle-tier (1st option) and leave the database concerned with what it does best - reading and writing data. However, the stored procedure will already be "tailored" to the specific view (think something along the lines of a report), and not used for anything else; thus, it just seems easier and lighter to process the permissions inside of the stored proc and bring back a prepared result with all the permissions already applied (a result that would have less data), rather than bringing back ALL the data into the middle tier and processing permissions there (eventually to discard half of the data anyway).
I am a bit torn and would appreciate some input. Intuitively, the 2nd option seems like a better fit, but "feels" very wrong.
Design the stored procedure to accept privileges enabled or features to use, e.g.
PROCEDURE retrieve_data (id_or_other_params,
anonymize := FALSE,
hide := FALSE,
some_other_feature := FALSE);
Procedure concerns now data retrieval only, with modifying options read from external source. Now let middle tier authenticate the user, decide which options to use and pass them to the procedure.
We use model first for tables and relations and database first for views and stored procedures.
If we change the model we have to:
-generate database
-create views and procedures
-add the procedures and the views to the model
-remap function call of procedures manually
This costs much time because the model changes often or has failures.
Does anyboy knows a workaround to automatically integrate the views and procedures in the model?
You could automate the process by creating your own template for generating DDL from SSDL. By default EF designer uses SSDLToSQL10.tt file but you could create your own .tt file which would generate DDL that better suits your needs. This should address 1) and 2). Once you have the database you could now update your model from the database. This should adress 3). Finally to address 4) you could write a Model Generation Extension that would tweak the model the designer builds from the database in the OnAfterModelGenerated/OnAfterModelUpdated method. (Be aware - some of the extension points in the designer are weird to say the least and might be confusing/hard to implement).
Another option you may want to explore is to use Code First and Migrations. With Migrations you could evolve your database instead of constantly creating/deleting it. If you need, you can use SQL to define a migration so you have full control of how your database looks like. Code First does not support some of the features supported by ModelFirst/DatabaseFirst (e.g. TVFs/FunctionImports) so you may want to check first if what's supported is enough for you.
I'm trying to understand choices for code generation tools/ORM tools and discover what solution will best meet the requirements that I have and the limitations present.
I'm creating a foundational solution to be used for new projects. It consists of ASP.NET MVC 3.0, layers for business logic and data access. The data access layer will need to go against Oracle for now, and then switch to SQL this year as the db migration is finished.
From a DTO standpoint mapping to custom types in the solution, what ORM/code generation tool will work with creating my needed code but can ONLY access Stored Procs in Oracle and SQL.?
Meaning, I need to generate the custom objects that are the artifacts from and being pushed to the stored procedures as the parameters, I don't need to generate the sprocs themselves, they already exist. I'm looking for the representation of what the sproc needs and gives back to be generated into DTOs. In some cases I can go against views and generate DTOs. I'm assuming most tools already do this. But for 90% of the time, I don't have access directly to any tables or views, only stored procs.
Does this make sense?
ORMs are best at mapping objects to tables (and/or views), not mapping objects to sprocs.
Very few tools can do automated code generation against whatever output a sproc may generate, depending on the complexity of the sproc. It's much more straight-forward to code generate the input to a sproc as that is generally well defined and clear.
I would say if you are stuck with sprocs, your options for using third party code to help reduce your development and maintenance time are severely limited.
I believe either LinqToSql or EntityFramework (or both?) are capable of some magic with regards to SQL Server to try to mostly automatically figure out what a sproc may be returning. I don't think it works all the time, it's just sophisticated guess work and I seriously doubt it would work with Oracle. I am not aware of anything else software-wise that even attempts to figure out what a sproc may return.
A sproc can return multiple diverse record sets that can be built dynamically by the sproc depending on the input and data in the database. A technical solution to automatically anticipating sproc output seems like it would require the following:
A static set of underlying data in the database
The ability to pass all possible inputs to the sproc and execute the sproc without any negative impact or side effects
That would give you a static set of possible outputs for any given valid input. A small change in the data in the database could invalidate everything.
If I recall correctly, the magic Microsoft did was something like calling the sproc passing NULL for all input parameters and assuming the output is always exactly the first recordset that comes back from the database. That is clearly an incomplete solution to the problem, but in simple cases it appears to be magic because it can work very well some of the time.
I'm in a VERY difficult problem.
I have a Microsoft Access Data Base, but it was made in the most chaotic way possible. The DB has like 150+ tables, Only uses like 50% of the tables. The relations are almost random. But, somehow, it delivers some information.
I need to get a particular component of the DB, but is so tangled that I can not manage to get into the table that creates that value. I revised every table, one by one, and found nothing.
I used mdbtools for Linux to try to inspect with more details the DB. But unfortunately has not been developed in years, and it closes every time. Maybe because the DB is "big" ? -700 mg-
I'm wondering: is there a way to see all the relations the arrives to the particular value I'm looking? Or to decompile the DB? I have no idea in which language it was made. I'm suspecting that it was made in Visual, just because is rather crappy.
Well, waiting for some help.
I would suggest using (still) MS Access for this. But, if relationships look messy on the diagram, you can query one of the system tables (MSysRelationships) directly to get ALL the relationships you need (e.g. for particular table etc.):
To unhide system tables in early versions of Access (97-2003), follow the instructions here:
For Access 2007, do the following:
I'm developing a web application in Node.js with MongoDB as the back end. What I wanted to know is, what is the generally accepted procedure, if any exists, for creating initial collections and populating them with initial data such as a white list for names or lists of predefined constants.
From what I have seen, MongoDB creates collections implicitly any time data is inserted into the database and the collection being inserted into doesn't already exist. Is it standard to let these implicit insertions take care of collection creation, or do people using MongoDB have scripts setup which build the main structure and insert any required initial data? (For example, when using MySQL I'd have a .sql script which I can run to dump and rebuild /repopulate the database from scratch).
Thank you for any help.
MHY
If you have data, this post on SO might be interresting for you. But since Mongo understands JavaScript, you can easily write a script that prepares the data for you.
It's the nature of Mongo to create everything that does not exist. This allows a very flexible and agile development since you are not constrainted to types or need to check if table x already exists before working on it. If you need to create collections dynamically, just get it from the database and work it if (no matter if it exists or not).
If you are looking for a certain object, be sure to check it (not null or if a certain key exists) because it may affect your code if you work with null objects.
There's is absolutely no reason to use setup scripts merely to make collections and databases appear. Both DB and collection creation is done lazily.
Rember that MongoDB is a completely schema free document store so there's no way to even setup a specific schema in advance.
There are tools available to dump and restore database content supplied with mongo.
Now, if your application needs initial data (like configuration parameters or whitelists like you suggest) it's usually best practice to have your application components set up there own data as needed and offer data migration paths as well.