Asp.net database migration, what's the Down method for? - asp.net-mvc-4

When I add-migration, Up and Down method are generated.
and I know when I update database (update-database), it runs the Up method.
How about Down method?
when it will run, is it for rollback? and, how can I run it?

Its for when you want to "downgrade" the database to a previous migration state. You use it with the -TargetMigration flag of the Update-Database command. For example, if you have added the following migrations:
Initial
FirstMigration
SecondMigration (current state)
You can revert the database to the Initial migration state by:
Update-Database -TargetMigration:Initial
In which case the code in the Down() methods of the SecondMigration and FirstMigration classes will run.

Related

Is there something like `SET UPDATE TASK LOCAL` for `CALL FUNCTION ... STARTING NEW TASK`?

In order to force CALL FUNCTION ... IN UPDATE TASK to be executed synchronosuly in the same LUW after COMMIT WORK there is a nice ABAP command SET UPDATE TASK LOCAL.
Is there something similar for CALL FUNCTION ... STARTING NEW TASK?
Background: I want to test some coding which I cannot change using database mocking with CL_OSQL_TEST_ENVIRONMENT. Unfortunately the instance of the test environment is only available in the current LUW when executing unit tests. If there is an asynchronous function module call then all the database accesses go to the database directly because the test environment is no longer valid in another LUW.

Running one specific Laravel migration (single file)

I don't want to run All Outstanding Migrations on laravel 4. I have 5 migrations. Now I just want to run one migration.
instead of doing : php artisan migrate
I would like to run one specific migration like : php artisan migrate MY_MIGRATION_TO_RUN
Looks like you're doing it wrong.
Migrations were made to be executed by Laravel one by one, in the exact order they were created, so it can keep track of execution and order of execution. That way Laravel will be able to SAFELY rollback a batch of migrations, without risking breaking your database.
Giving the user the power to execute them manually, make it impossible to know (for sure) how to rollback changes in your database.
If your really need to execute something in your database, you better create a DDL script and manually execute it on your webserver.
Or just create a new migration and execute it using artisan.
EDIT:
If you need to run it first, you need to create it first.
If you just need to reorder them, rename the file to be the first. Migrations are created with a timestemp:
2013_01_20_221554_table
To create a new migration before this one you can name it
2013_01_19_221554_myFirstMigration
You can put migrations in more folders and run something like:
php artisan migrate --path=/app/database/migrations/my_migrations
Just move the already run migrations out of the app/config/database/migrations/ folder . Then run the command php artisan migrate . Worked like a charm for me .
A nice little snippet to ease any fears when running Laravel 4 migrations php artisan migrate --pretend . This will only output the SQL that would have been run if you ran the actual migration.
It sounds like your initial 4 migrations have already been run. I would guess that when you php artisan migrate it will only run the new, recent migration.
Word of advice: makes sure all of your up() and down() work how you expect them to. I like to run up(), down(), up() when I run my migrations, just to test them. It would be awful for you to get 5-6 migrations in and realize you can't roll them back without hassle, because you didn't match the down() with the up() 100% percent.
Just my two cents! Hope the --pretend helps.
The only way to re run a migrattion is a dirty one. You need to open your database and delete the line in the migrations table that represents your migration.
Then run php artisan migrate again.
You can create a separate directory for your migrations from your terminal as follows:
mkdir /database/migrations/my_migrations
And then move the specific migration you want to run to that directory and run this command:
php artisan migrate --path=/database/migrations/my_migrations
Hope this helps!
If you want to run(single file) migration in Laravel you would do the following:
php artisan migrate --path=/database/migrations/migrations_file_name
eg.
C:\xampp\htdocs\laravelv3s>php artisan migrate --path=/database/migrations/2020_02_14_102647_create_blogs_table.php
I gave this answer on another post, but you can do this: run artisan migrate to run all the migrations, then the following SQL commands to update the migrations table, making it look like the migrations were run one at a time:
SET #a = 0;
UPDATE migrations SET batch = #a:=#a+1;
That will change the batch column to 1, 2, 3, 4 .. etc. Add a WHERE batch>=... condition on there (and update the initial value of #a) if you only want to affect certain migrations.
After this, you can artisan migrate:rollback as much as is required, and it'll step through the migrations one at a time.
You can use below solution:
create your migration.
check your migration status like: php artisan migrate:status.
copy the full name of new migration and do this like: php artisan migrate:rollback --path:2018_07_13_070910_table_tests.
and then do this php artisan migrate.
finally, you migrate specific table.
Goodluck.
If you want to run your latest migration file you would do the following:
php artisan migrate
You can also revert back to before you added the migration with:
php artisan migrate: rollback
There is one easy way I know to do this can only be available for you on just local host
Modify your migration file as needed
open your phpMyAdmin or whatever you use to see your database table
find the desired table and drop it
find migrations table and open it
in this table under migration field find your desired table name and delete its row
finally run the command php artisan migrate from your command line or terminal. this will only migrate that tables which not exists in the migrations table in database.
This way is completely safe and will not make any errors or problems while it looks like un-professional way but it still works perfectly.
good luck
If it's just for testing purposes, this is how i do it:
For my case, i have several migrations, one of them contains App-Settings.
While I'm testing the App and not all of the migrations are already setup i simply move them into a new folder "future". This folde won't be touched by artisan and it will only execute the migration you want.
Dirty workaround, but it works...
I have same problem.
Copy table creation codes in first migration file something like below:
public function up()
{
Schema::create('posts', function(Blueprint $table){
$table->increments('id');
// Other columns...
$table->timestamps();
});
Schema::create('users', function (Blueprint $table) {
$table->increments('id');
// Other columns...
$table->softDeletes()->nullable();
});
}
Also you can change(decrease) batch column number in migrations table ;)
And then run php artisan migrate.
Throw an exception in a migration, if you don't want to apply it, and it would stop the whole process of migration.
Using this approach you can split your bunch of migrations into steps.
Working in Laravel 8+
Run single specific migration:
php artisan migrate --path=/database/migrations/yourfilename.php
Run all migrations:
php artisan migrate
so simple...! just go to your migration folder. move all migration files into another folder. then return all migration one by one into migration folder and run migration for one of them(php artisan). when you insert bad migration file into master migration folder and run php artisan migrate in command prompt will be error.
I used return on line 1 so the previous dbs are retained as it is.
<?php
use Illuminate\Support\Facades\Schema;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Database\Migrations\Migration;
class CreateUsersTable extends Migration
{
/**
* Run the migrations.
*
* #return void
*/
public function up()
{
return; // This Line
Schema::create('users', function (Blueprint $table) {
$table->increments('id');
$table->string('name', 50);
$table->string('slug', 50)->unique();
$table->integer('role_id')->default(1);
$table->string('email', 50)->unique();
$table->timestamp('email_verified_at')->nullable();
$table->string('mobile', 10)->unique();
$table->timestamp('mobile_verified_at')->nullable();
$table->text('password');
$table->integer('can_login')->default(1);
$table->rememberToken();
$table->timestamps();
});
}
/**
* Reverse the migrations.
*
* #return void
*/
public function down()
{
return;// This Line
Schema::dropIfExists('users');
}
}
This is a bad approach of which I use.. I'll delete other migration files except the specific file I want to migrate then run PHP artisan migrate after migration is completed I'll goto my trash bin and restore the deleted files
For anybody still interested in this, Laravel 5 update: Laravel has implemented the option to run one migration file at a time (in version 5.7).
You can now run this:
php artisan migrate --path=/database/migrations/my_migration.php (as answered here)
Because the Illuminate\Database\Migrations\Migrator::getMigrationFiles() now contains this code:
return Str::endsWith($path, '.php') ? [$path] : $this->files->glob($path.'/*_*.php');
(see the source code.)
But in my usecase, I actually wanted to run a set of migrations at the same time, not just one, or all.
So I went the Laravel way and registered a different implementation of the Migrator, which decides which files to use:
/**
* A migrator that can run multiple specifically chosen migrations.
*/
class MigrationsSetEnabledMigrator extends Migrator
{
/**
* #param Migrator $migrator
*/
public function __construct(Migrator $migrator)
{
parent::__construct($migrator->repository, $migrator->resolver, $migrator->files);
// Compatibility with versions >= 5.8
if (isset($migrator->events)) {
$this->events = $migrator->events;
}
}
/**
* Get all of the migration files in a given path.
*
* #param string|array $paths
* #return array
*/
public function getMigrationFiles($paths)
{
return Collection::make($paths)->flatMap(function ($path) {
return Str::endsWith($path, ']') ? $this->parseArrayOfPaths($path) :
(Str::endsWith($path, '.php') ? [$path] : $this->files->glob($path . '/*_*.php'));
})->filter()->sortBy(function ($file) {
return $this->getMigrationName($file);
})->values()->keyBy(function ($file) {
return $this->getMigrationName($file);
})->all();
}
public function parseArrayOfPaths($path)
{
$prefix = explode('[', $path)[0];
$filePaths = explode('[', $path)[1];
$filePaths = rtrim($filePaths, ']');
return Collection::make(explode(',', $filePaths))->map(function ($filePath) use ($prefix) {
return $prefix . $filePath;
})->all();
}
}
We have to register it into the container as 'migrator' (to be accessible as $app['migrator']), because that is how Migrate command accesses it when itself is being registered into the IoC. To do so, we put this code into a service provider (in my case, it is a DatabaseServiceProvider):
public function register()
{
$this->app->extend('migrator', function ($migrator, $app) {
return new MultipleSpecificMigrationsEnabledMigrator($migrator);
});
// We reset the command.migrate bind, which uses the migrator - to
// force refresh of the migrator instance.
$this->app->instance('command.migrate', null);
}
Then you can run this:
php artisan migrate --path=[database/migrations/my_migration.php,database/migrations/another_migration.php]
Notice the multiple migration files, separated by a comma.
It is tested and working in Laravel 5.4 and should be Laravel 5.8 compatible.
Why?
For anyone interested: the usecase is updating the version of database along with it's data.
Imagine, for example, that you wanted to merge the street and house number of all users into new column, let's call it street_and_house. And imagine you wanted to do that on multiple installations in a safe and tested way - you would probably create a script for that (in my case, I create data versioning commands - artisan commands).
To do such an operation, you first have to load the users into memory; then run the migrations to remove the old columns and add the new one; and then for each user assign the street_and_house=$street . " " . $house_no and save the users. (I am simplifying here, but you can surely imagine other scenarios)
And I do not want to rely on the fact that I can run all the migrations at any given time. Imagine that you wanted to update it from let's say 1.0.0 to 1.2.0 and there were multiple batches of such updates – performing any more migrations could break your data, because those migrations must be handled by their own dedicated update command. Therefore, I want to only run the selected known migrations which this update knows how to work with, then perform operations on the data, and then possibly run the next update data command. (I want to be as defensive as possible).
To achieve this, I need the aforementioned mechanism and define a fixed set of migrations to be run for such a command to work.
Note: I would have preferred to use a simple decorator utilizing the magic __call method and avoid inheritance (a similar mechanism that Laravel uses in the \Illuminate\Database\Eloquent\Builder to wrap the \Illuminate\Database\Query\Builder), but the MigrateCommand, sadly, requires an instance of Migrator in it's constructor.
Final note: I wanted to post this answer to the question How can I run specific migration in laravel , as it is Laravel 5 - specific. But I can not - since that question is marked as a duplicate of this one (although this one is tagged as Laravel 4).
You may type the following command:
php artisan migrate --help
...
--path[=PATH] The path(s) to the migrations files to be executed (multiple values allowed)
...
If it does show an option called "--path" (like the upper example) that means your Laravel version supports this parameter. If so, you're in luck can then you can type something like:
php artisan migrate --path=/database/migrations/v1.0.0/
Where "v.1.0.0" is a directory that exists under your "/database/migrations" directory that holds those migrations you want to run for a certain version.
If not, then you can check in your migrations table to see which migrations have already been run, like this:
SELECT * FROM migrations;
And then move out of your "/database/migrations" folder those which were executed. By creating another folder "/databases/executed-migrations" and moving your executed migrations there.
After this you should be able to execute:
php artisan migrate
Without any danger to override any existing table in your schema/database.
(*) example for Windows:
php artisan migrate --path=database\migrations\2021_05_18_121604_create_service_type_table.php

How to save and then update same class instance during one request with NHibernate?

I'm relatively new to NHibernate and I've got a question about it.
I use this code snippet in my MVC project in Controller's method:
MyClass entity = new MyClass
{
Foo = "bar"
};
_myRepository.Save(entity);
....
entity.Foo = "bar2";
_myRepository.Save(entity);
The first time entity saved in database succesfully. But the second time not a single request doesnt go to database. My method save in repository just does:
public void Save(T entity)
{
_session.SaveOrUpdate(entity);
}
What should I do to be able to save and then update this entity during one request? If I add _session.Flush(); after saving entity to database it works, but I'm not sure, if it's the right thing to do.
Thanks
This is the expected behavior.
Changes are only saved on Flush
Flush may be called explicitly or implicitly (see 9.6. Flush)
When using an identity generator (not recommended), inserts are sent immediately, because that's the only way to return the ID.
you should be using transactions.
a couple of good sources: here and here.
also, summer of nHibernate is how I first started with nHibernate. it's a very good resource for learning the basics.

Updating models in a Doctrine Migration

I'm trying to update a model in the context of a Doctrine_Migration. Calling save() on the object doesn't seem to update the database. I also tried calling execute() a Doctrine_Query in the context of a Doctrine_Migration. I tried running getSqlQuery() on the query object and I get a valid query that works if executed in a mysql console, however if I just run the migration normally I get no errors and the execute() doesn't seem to do anything.
How can successfully execute() a query in the context of a migration?
$res = Doctrine_Query::create()->update('FooBar')->set('colFoo', '?', 'valBar')->execute();
This should do the trick

NHibernate FlushMode: How do I set up NHibernate for automatically updating an entity

After I retrieve an entity, I change a property of it.
Then I retrieve the same entity.
How do I say Nhibernate, that it shall update the entity before it loads the entity?
Here the code:
EmployeeRepository employeeRepository = new EmployeeRepository();
Employee employee = employeeRepository.GetById(4);
employee.LastName = "TEST!!!";
Employee employee2 = employeeRepository.GetById(4);
Currently Nhibernate don't make an update in my program. I thought just setting the FlushMode to Auto will update the entity automatically.
EDIT
The background is that I try to reprdouce this behaviour in another application.
There is NO save method! Just this code. The NHibernate version is really old, it is version 1.2.1.4000. maybe there is the catch.
When I set the FlushMode in the brownfield application to Commit then no update statement is generated.
But in my own project I still can not reproduce this "automatic" behaviour.
Are both calls to the employeeRepository ultimately using the same NHibernate ISession instance? If so, then they will return the same object, and the updated LastName value will be reflected. If not, then you will need to make sure you are disposing your ISession instance each time to take advantage of auto flushing.
According to the documentation for the default FlushMode of Auto:
The ISession is sometimes flushed
before query execution in order to
ensure that queries never return stale
state. This is the default flush mode.
So you have to manually flush the session to ensure that your changes are persisted before reading the object again.
EmployeeRepository employeeRepository = new EmployeeRepository();
Employee employee = employeeRepository.GetById(4);
employee.LastName = "TEST!!!";
session.Flush();
Employee employee2 = employeeRepository.GetById(4);
If your repository is using the same ISession for both calls (as it should imo) then employee 4 will be retrieved from the cache and have the change. However, the change will not have been persisted to the database yet.
If your repository GetById methods uses a new session for each call then it will always hit the database to retrieve the employee. If you're disposing of the session in the method then your objects are returned as detached from a session. This strategy defeats the purpose of NHibernate and relegates it to a simple data access tool.