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.
Related
I removed a model fully from my app: deleted the model.js and model.json from models, deleted a relation in another model, and erased it from model-config.json.
However, the table created for the model, and the column in the other model remain in the DB (in all environments). I tried auto-migrating, but they're still there.
Do I need to manually go through all databases and drop the table and column manually, or can I tell LB to pick up the changes on its own somehow?
Do I need to manually go through all databases and drop the table and column manually, or can I tell LB to pick up the changes on its own somehow?
LoopBack is not able to detect which models were removed and drop the corresponding database tables.
As you have discovered yourself, the solution is to go through the databases and drop the tables manually.
BTW I don't recommend using LoopBack's autoupdate/automigrate functionality in production and highly advocate for maintaining a set of migration scripts as described e.g. in Martin Fowler's excellent article Evolutionary Database Design.
LoopBack does not support migration scripts yet, but we are discussing how to implement them for LoopBack 4+, see https://github.com/strongloop/loopback-next/issues/487
Have you looked into using the built-in API?
https://apidocs.strongloop.com/loopback/#app-deletemodelbyname
Ended up doing it manually - in 3 databases :(
I'm closing the question, but willing to reopen if someone had a good answer.
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.
I evaluating CouchDB & I'm wondering whether it's possible to achieve the following functionality.
I'm planning to develop a web application and the app should allow a 'parent' table and derivatives of this table. The parent table will contains all the fields (master table) and the user will selectively choose fields, which should be saved as separate tables.
My queries are as follows:
Is it possible to save different versions of the same table using CouchDB?
Is there an alternative to creating child tables (and clutter the database)?
I'm new to NoSQL databases and am evaluating CouchDB because it supports JSON out of the box and this format seems to fit the application very well.
If there are alternatives to NOT save the derivatives as separate tables, the better will the application be. Any ideas how I could achieve this?
Thanks in advance.
CouchDB is a document oriented database which means you cannot talk in terms of tables. There are only documents. The _rev (or revision ID) describes a version of a document.
In CouchDB, there are 2 ways to achieve relationships.
Use separate documents
Use an embedded array
If you do not prefer to clutter your database, you can choose to use option (2) by using an embedded array.
This gives you the ability to have cascade delete functionality as well for free.
I am wondering about the model-first approach. I wish to design a new database using the model designer in VS2012. The new features of the model designer such as coloring and splitting up model sections are wonderful. Hopefully there will be purpose for using the model designer beyond initially creating a new database.
I would like to perform the following steps...
using the model designer, visually design and push the model to create the initial database and a table
add data to the table
make a change to the table in the model designer (e.g. add a field)
push the changes to the database (i.e. update the database)
NOT LOSE MY DATA FROM STEP 2. Also, just to clear any confusion... did I mention that I DON'T WISH TO LOSE THE DATA?
Please, please tell me this obvious need (i.e. the need to evolve the the tables and their fields without losing data, starting from scratch) has not been overlooked in iteration FIVE of EF.
This page on EF (http://msdn.microsoft.com/en-us/data/ee712907.aspx) makes things sound that the developer has equal choices between coding first and modeling first. To me, the intro video on the page creates a similar impression.
It would be nice if there were a simple menu option or better yet just a way to establish "automatic pushes to DB" upon changes to the model. That way whenever changes are made and the SAVE button is clicked, a dialog could appear "Update database?".
I see that using code-first there is a migrations option. I cannot seem to find the same for model-first. And I don't understand why this wouldn't be possible... after all the code that I would have written in code-first does indeed exist - it was created by the model-first code generation.
I'm keeping my fingers crossed in hopes someone will have a simple solution, perhaps something I've just overlooked and all this rambling/venting is in vain. :-)
You really have to use code-first if you want to modify your database when the model changes. Even then it's not some magical automated process but you'll have to script the changes.
With model first your best option is to generate a new database each time and create a change script (DDL) by using a tool like Redgate's SQL Compare or a Visual Studio Sql Server Database Project.
I'd like to add that it is virtually impossible to synchronize a database automatically with a model. Some changes require manual intervention, e.g. removing a field and adding another field cannot be distinguished from renaming/retyping a field. Some changed can easily be done in a model, but would require a table rebuild script in Sql Server (e.g. changing field order), or a combination of modified content and structure (e.g. making a field not null, adding a foreign key).
At the moment the only thing to do is:
Copy your database file... (backup)
Allow EF to recreate the database according to model
Per table copy-paste your records from backup to your new db.
This is not that easy as you need to copy paste in a specific order because of relations and it will only be good for minor changes such as adding columns and new tables or removing scalar columns or removing tables.
But I am certain that this is the begining of a correct approach to deal with the problem which later on can be automated by writing a more generic migration app between two databases which share same table names and relations.
Deeper problems begin when the relations are not the same / table names changed / column names changed.
Following up on my previous post, I need to be able to query a database of 6M+ rows in the fastest way possible, so that this DB can be effectively used as a "remote" data source for a dynamic Excel report.
Like I said, normally I would store the data I need on a separate (perhaps hidden) worksheet and I would manipulate it through a second "control" sheet. This time, the size (i.e. number of rows) of my database prevents me from doing so (as you all know, excel cannot handle more than 1,4M rows).
The solution my IT guy put in place consists of holding the data on a txt file inside of a network folder. This far, I managed to query this file through ADO (slow but no mantainance needed) or to use it as a source to populate an indexed Access table, which I can then query (faster but requires more mantainance & additional software).
I feel both solutions, although viable, are sub-optimal. Plus it seems to me as all of this is but an unnecessary overcomplication. The txt file is actually an export from SAP BO, which the IT guy has access to through WEBI. Now, can't I just query the BO database through WEBI myself in a "dynamic" kind of way?
What I'm trying to say is, why can't I extract only bits of information at a time, on a need-to-know basis and directly from the primary source, instead of having all of the data transfered in bulk on a secondary/duplicate database?
Is this sort of "dynamic" queries even possible? Or will the "processing" times hinder the success of my approach? I need this whole thing to really feel istantaneuos, as if the data was already there and I'm not actually retrieving it all the times.
And most of all, can I do this through VBA? Unfortunately that's the only thing I will be having access to, I can't do this BO-side.
I'd like to thank you guys in advance for whatever help you can grant me!
Webi (short for Web Intelligence) is a front-end analytical reporting application from Business Objects. Your IT contact apparently has created (or has access to) such a Webi document, which retrieves data through a universe (an abstraction layer) from a database.
One way that you could use the data retrieved by Web Intelligence as a source and dynamically request bits instead of retrieving all information in one go, it to use a feature called BI Web Service. This will make data from Webi available as a web service, which you could then retrieve from within Excel. You can even make this dynamic by adding prompts which would put restrictions on the data retrieved.
Have a look at this page for a quick overview (or Google Web Intelligence BI Web Service for other tutorials).
Another approach could be to use the SDK, though as you're trying to manipulate Web Intelligence, your only language options are .NET or Java, as the Rebean SDK (used to talk to Webi) is not available for COM (i.e. VBA/VBScript/…).
Note: if you're using BusinessObjects BI 4.x, remember that the Rebean SDK is actually deprecated and replaced by a REST SDK. This could make it possible to approach Webi using VBA after all.
That being said, I'm not quite sure if this is the best approach, as you're actually introducing several intermediate layers:
Database (holding the data you want to retrieve)
Universe (semantic abstraction layer)
Web Intelligence
A way to get data out of Webi (manual export, web service, SDK, …)
Excel
Depending on your license and what you're trying to achieve, Xcelsius or Design Studio (BusinessObjects BI 4.x) could also be a viable alternative to the Excel front-end, thereby eliminating layers 3 to 4 (and replacing layer 5). The former's back-end is actually heavily based on Excel (although there's no VBA support). Design Studio allows scripting in JavaScript.