Is it possible to create a CRUD system without database in spring mvc framework?
If possible then which way?
I made an application where i can save and update a single value but i need to save and update a list of value.
HSQLDB offers in memory DB, you can use it to do crud operations for your unit tests. You can maintain spring configuration for the Unit tests and another spring configuration for deployed code. The db configuration can be different for both, so, you run the data updates on the in-memory databse when running tests and actual database when deployed to server. Spring takes care of this seamlessly.
http://hsqldb.org/ spring boot has this inbuild
Other ways to test out your code is to using mockito where you test your code on mock data/objects.
Update: there is something called DBUnit, just found out, it can also help you test against fake db
You Can recreate a CRUD operation using File Systems In Java using a File or Excel as a Database and and then Using File Handling or Apache POI in order to Create Update or Delete.
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Looking for recommended mechanism where Java MicroService needs to access postgress table. No need to expose this data via endpoint.
MVC style access uses repo, entity and controller (Springboot framework)
write function to connect DB and perform SELECT calls
Is it possible to combine 1(skip controller) & 2 ?
Please advice
Question 1 (with skipping controller): perfectly fine. You still need to query the db and process the result. And most of the time this is the easiest with JPA and spring repositories.
Question 2: perfectly fine
Combine 1 & 2: It is possible of course. When you have entities and repositories, you can still use native select calls if you need for some specific functionality (probably because of the complexity of the queries). Have a look at spring jdbctemplate: https://www.baeldung.com/spring-jdbc-jdbctemplate
I have a simple REST app with MySQL database, everything works fine, but while testing do we need to create a dummy object and test on it, or test via Mock database?
The dummy object has quite large constructor and nested classes, which is a lot of work.
IMO, there's little point using a mock database, unless you're testing connectivity handling. For example, how does my application behave if the database connection is dropped etc.
For testing SQL, you will do no better than testing against the actual database you're going to use in production. If you use another database as a substitute, i.e. H2, make sure you understand that you are testing a DB driver and database that will be different to your production deployment and this means that you may not catch potential errors in your tests that use this setup.
For testing data handling, you could also use a mock of some kind but again, if you're always going to be better off using the actual database you will be using in production, whenever you can.
If you're using Hibernate as an ORM provider, as part of setting up your integration tests, you can have it execute DML scripts to load your data for testing purposes.
If you using spring boot, then H2 is one of the popular in memory databases. Spring Boot has very good integration for H2.
For integration tests, you should consider using a database in-memory, such as H2.
H2 supports compatibility modes for IBM DB2, Apache Derby, HSQLDB, Microsoft SQL Server, MySQL, Oracle and PostgreSQL. To use the MySQL mode, use the database URL as shown below (and refer to the documentation for further details):
jdbc:h2:~/test;MODE=MySQL;DATABASE_TO_LOWER=TRUE
I want to build a server for my android application.
My application lets users register and allows each user to request a list of all users registered to my application, so my server will be mainly in charge of receiving data from a user, updating the database, and sending data back to user on request.
Since I've never built a server I looked into what would be the ideal way to achieve my goals and after some reading I've found that Spring would be the right way to go, But I also found that there are all kinds of springs.
Eventually I've narrowed my options down to Spring MVC and spring Boot,
I've read that spring boot is a good start but I also read that spring boot does all the configurations for you and I want to really know how stuff works so I fear that spring boot will do all the work for me , So I thought of maybe using spring MVC but I couldn't completely figure out if Spring MVC would be good to achieve my goals or if it's mainly used for building web pages
So what would be the best suitable spring to use ?
I would prefer Spring boot. It's not just about it doing all the configuration for you. It's about Spring saving you from writing a lot of boilerplate code (you still have to do a fair bit of configuration though). Plus, it will be easy to spin up the app and test it locally (you can even test it with local file based h2 database, meaning you don't need to install any database into your machine).
Adding Spring Data JPA dependency with Spring boot will take care of persistent layer as well. And if you want to write jsp or html pages then I would recommend having a look at this thymeleaf example.
Here's the sample CRUD application I have developed with Spring boot and here's my own blog about it.
Spring MVC stands for model,view,controller. View, in general is something which is returned after your business logic has been executed and mainly suggests webpages. Spring Boot would be the easiest way to set up your server for the application. However, if you want to know how things work you can go with the basic spring. Spring, too provided classes like JdbcTemplate to reduce your boilerplate code, however it forces you to configure things yourself.
You do not have the comfort of annotating a resource and watching as the magic happens. If you want to speed up setting up a server and make things less complex go for Spring Boot.
I've read the following posts:
Is there a way to run MySQL in-memory for JUnit test cases?
Stubbing / mocking a database in .Net
SQL server stub for java
They seem to address unit/component level testing (or have no answers), but I'm doing system testing of an application which has few test hooks. I have a RESTful web service backed by a database with JPA. I'm using NUnit to run tests against the API, but those tests often need complex data setup and teardown. To reduce the cost of doing this within a test via API calls, I would like to create (ideally in memory) databases which can be connected to via a DB provider using a connection string. The idea would be to have a test resource management service which builds databases of specific types, allowing a test to re-point the SUT to a new database with the expected data when it starts - one which can simply be dropped on teardown.
Is there a way, using Oracle or MSSQL, to create a database in memory (could be something as simple as a C# DataSet) which the web server can talk to as if it were a production database? Quick/cheap creation and disposal would be as good as in memory, to be honest.
I feel like this is a question that should have an answer already, but can't find it/ don't understand enough to know that I've found it.
So, I have a Java EE application using Spring framework and JDBCtemplate. And, my application has to do several JDBC database read requests (no/very little writes) on the same database (which is a Postgres DB but is not normalized for a bunch of reasons) but with different sql statements (different where clauses). So, given this situation, I would like to be able to cache the database and be able to run queries on the cache, thereby saving me expensive JDBC calls. So, please suggest appropriate tools or frameworks or any other solutions.
You can start with using simple maps depending the query parameter you are using. A more viable solution is using ehcache.
If you use Spring 3.1 or later, you can use #Cacheable on methods. You need to include <cache:annotation-driven /> in your application context configuration. For simple cases you may use spring's ConcurrentCacheFactoryBean as cache manager. For more complex cases you can use ehcache via spring's ehcache adapter. Use #CacheEvict to reset cache.