I use jooq to generate objects against a local database, but when running "for real" later in production the actual databases will have different names. To remedy this I use the <outputSchemaToDefault>true</outputSchemaToDefault> config option (maven).
At the same time, we have multiple databases (schemas), and are using a connection pool to the server like "jdbc:mysql://localhost:3306/" (without specifying a database here).
How do I tell jooq which database to use when running queries?
I have tried all config I can think of:
new Settings()
.withRenderSchema(true) // true/false seems to make no difference.
.withRenderCatalog(true) // true/false seems to make no difference.
.withRenderMapping(new RenderMapping()
.withDefaultSchema("my_database") // Seems to have no effect.
// The above 3 configs always give me an error saying "no database selected".
// Adding this gives me 'my_database.my_table' does not exist - while it actually does.
.withSchemata(new MappedSchema()
.withInputExpression(Pattern.compile(".*"))
.withOutput("my_database")
));
I have also tried using a database/schema name, as in not configuring outputSchemaToDefault. But then, adding the MappedSchema code above, but that gives me errors with "'my_databasemy_database.my_table' does not exist", which is correct. I have no clue why that code gives me the database/schema name twice?
Edit:
When jooq tells me that the db.table does not exist, if I put a break point in a good place and get the sql from jooq and run exactly that against my database it does work. But jooq fails to run it.
Also, I'm using version 3.15.3 of jooq.
I solved it. Instead of using .withInputExpression(Pattern.compile(".*")), it seems to work with .withInput("").
I'm still not sure why it works, or if this is the "correct" way of solving it. But at least it is a way forward.
No clue why using the pattern, I got the name twice though. But that one I'll leave alone.
I am using node-storage in the following code to store a value in a file, however when I create a new storage object changes from another storage object are not yet saved. I need a way to save the changes before creating the new storage object.
Below is a program called code.js which I am running like so in the console: node code.js. If you run it you will see that the first time it is run the key value pair doesn't yet exist however it does exist the second time.
key = "key"
storage = require('node-storage')
const store1 = new storage("file")
const store2 = new storage("file")
store1.put(key,'val')
console.log(store2.get(key))
My motivation for this is that I want to be able to have a function called "set" which takes a key and a value and sets the key value pair in a dictionary of values that is store in a file. I want to be able to refer to this dictionary later, with for example a 'get' function, and have the changes present.
I am thinking there might be a function called "save" or something similar that applies the changes to the file. Is there such a function or some other solution?
node-storage saves the changes in the dictionary to disk after every call to put or remove. This is not the issue.
Your problem is that the dictionary in store2 has not been updated with the new properties. node-storage only loads the file from disk when the object is first created.
My suggestion would be to only have one instance of storage per file.
However, if this is not possible, then you might want to consider updating store2's cache before you get the property. This can be done using:
store2.store = store2._load();
This may not be the best for performance, as _load loads the entire file from disk synchronously every time it is called, so try to limit its use.
The Situation
I recently started working on a new project using nodejs. I have a background of using Python/Django and C#/.NET (not a huge fan of the latter). Node is awesome, but I must say I miss the ease of building models and automating migrations in Django. I am currently using the AdonisJS framework which leverages Knex. Knex is a powerful library, but the migrations all need to be manually built. Additionally, the AdonisJS ORM that manages the Models is independent of Knex (migration manager). You also do not define field attributes on the Models, which can have benifits for dynamically doing things in the front and back end. All things considered, there is a lot of room for human error, miscommunication and a boat load more typing required. I know the the hot thing these days is to keep it loose and fast, but for this specific project, I am looking for a bit more structure than loosely defined models.
Current State
What I have landed on is building a new Class called tableModel and a field class to define the fields within table model. I have already completed this and I am successfully writing the migration files leveraging mustache. I plan on also automatically writing the Models which I shouldn't have a problem with (fingers crossed).
The Problem
Here is where it gets a little tough and where I need help...I need to track what has been added or removed via migration so I can effectively write ups and downs as the tableModels change over time.
So let's say I add a "tableModel" which creates a migration to create table Foo with fields {id (bigint), user_id(int), name(string255)}
Later I want to add a field called description so I would simply add it to my "tableModel" and then run a build command which would build out the migration.
How do I check what has already been created though so I only do an up() for description?
Then I want to remove the name field so I mark it out in my "tableModel" and run a build migration command. How do I check what has been migrated that now needs to be added in to the down().
Edit: I would add a remove field to the up and the corresponding roll back to the down.
Bonus Round
Let's say I want to change user_id from an int to a bigint, because who makes a foreign key just an int? How do I check not just what needs to be added to the up and down, but also checks if I need to change a property on a field.
Edit: would just write the up. and a corresponding roll back to the down
The Big Question
Basically, how do I define dirty "tableModels" classes
Possible Solution?
I am thinking that maybe I should capture some type of registry or snapshot and then run the comparison when building the migrations and or models, then recapture/snapshot. If this is the route, should I store in a json file, write this to the DB itself, or is there another/better option.
If I create the tableModel instances as constants, could I actually write back to the JS file and capture the snapshot as an attribute? IF this is an option, is Node's file system the way to go and what's the best way to do this? Node keep suprising me so I wouldn't be baffled if any of these are an option.
Help!
If anyone has gone down this path before or knows of any tools I could leverage, I would greatly appreciate it and thank you in advance. Also, if I am headed in a completely wrong direction, then please let me know, I both handle and appreciate all types of feedback.
Example
Something to note, when I define the "tableModel" for a given migration or model, it is an instance of the class, I am not creating an extended class since this is not my orm.
class tableModel {
constructor(tableName, modelName = tableName, fields = []) {
this.tableName = tableName
this.modelName = modelName
this.fields = fields
}
// Bunch of other stuff
}
fooTableModel = new tableModel('fooTable', 'fooModel', fields = [
new tableField.stringField('title'),
new tableField.bigIntField('related_user_id'),
new tableField.textField('description','Testing Default',false,true)
]
)
which equates to:
tableModel {
tableName: 'fooTable',
modelName: 'fooModel',
fields:
[ stringField {
name: 'title',
type: 'string',
_unique: false,
allow_null: null,
fieldAttributes: {},
default_value: null },
bigIntField {
name: 'related_user_id',
type: 'bigInteger',
_unique: false,
allow_null: null,
fieldAttributes: {},
default_value: 0 },
textField {
name: 'description',
type: 'text',
_unique: false,
allow_null: true,
fieldAttributes: {},
default_value: 'Testing Default' } ]
You have the up and down notation mixed up. Those are for migrating the "latest" (runs the up function) and doing rollbacks (runs the down function). Up and down to not relate to dropping or adding table columns.
The migrations up is for any change, and the down is to reverse those changes. So if you wanted to drop a column from some table, you write the command in the up, then write the opposite in the down (you'd add it back in...), such that you can "rollback" and the change is effectively reversed. You have to be careful with such things though, as you can put yourself in a situation where you actually lose data.
Want to add a column? Write it in the up, and drop the column in the down.
One of the major points behind the migrations mechanism is to track the state of changes of your database, as time goes forward. So generally, if you created a table in some migration, then a day or so later you realize you need to drop/add columns, you normally don't go back and edit the existing migration, especially if the migration has already been run. You'd just write a new migration to drop/add your column.
Since you're using knex, there are a couple "knex" tables that get created. By default the one you're looking for is knex_migrations, unless someone specifically modified the settings to change the name of it. This table holds all the migrations that have run against your DB, per batch. From the CLI, assuming you have knex.js installed globally, you can run knex migrate:latest, and that will push all the migrations that exist in your directory to the target database, if they have not yet been run. It does this by way of examining that knex_migrations table. If you roll a change and don't like it, and assuming you've properly done the down function, you can invoke knex migrate:rollback to reverse the change. If there are 3 migration files that have NOT yet been run, invoking knex migrate:latest will run all 3 of those migration files under a new batch #, which is 1 higher than the most recent batch number. Conversely, if you invoke a knex migrate:rollback, it will find the highest batch number (there could be more than 1 migration in a batch...), and invoke the down function on all those files, effectively rollback those changes.
All that said, knex is a "query builder" tool. It's got a ton of helper functions to help build the sql for you. Personally, I find this to be a major distraction. Why spend hours on hours figuring out all the helper functions when I can just go crank out raw SQL and run that. Thus, that's what we've done in our system. we use knex.raw('') and write our own DDL and DML. It works great and does exactly what we need it to. We don't need to go figure out the magic of the query building.
The short answer is that knex will automatically know what has and has not been run for you (again, via that knex_migrations table it creates for you...).
Things can get weird though when it start involving git and different branches. I recommend that if you're writing migrations on some branch, and you need to go do other work, always remember to first perform a rollback of any migrations you've done in that branch BEFORE switching branches. Otherwise you will be in weird DB states that don't coincide with the application code.
I would personally just deal with updating models independently of writing migrations. For example, if I'm adding a description column to some table, then I probably want to manually update the ORM to reflect the change of the new db schema. Generally, I've found trying to use a tool that automagically does that for you (rather, if I change the orm, stuff happens to write all the underlying sql...) usually winds me up in a heap of trouble and I just spend more time trying to un-fudge stuff. But, that's just my 2 cents :)
Here is where it gets a little tough and where I need help...I need to track what has been added or removed via migration so I can effectively write ups and downs as the tableModels change over time.
You could store changes in a DB/txt file and those can act as snapshots. So when you want to rollback to a particular migration, you would find the changes (up/down) made for that mutation and adjust accordingly.
Later I want to add a field called description so I would simply add it to my "tableModel" and then run a build command which would build out the migration. How do I check what has already been created though so I only do an up() for description?
Here you either call the database itself directly and check what fields have already been created. If a field is already their and the attributes are the same, you can either ignore it or stop the transaction all together.
Bonus Round Let's say I want to change user_id from an int to a bigint, because who makes a foreign key just an int? How do I check not just what needs to be added to the up and down, but also checks if I need to change a property on a field.
Again, call the DB itself on the table in question. I know the SQL call would be:
describe [table_name];
After reading the end, I think you answered this yourself, but I think capturing these changes would work best in a NoSql database since you're using Node or PostGres with it's json field.
A deployment script creates and configures databases, collections, etc. The script includes code to drop databases before beginning so testing them can proceed normally. After dropping the database and re-adding it:
var graphmodule = require("org/arangodb/general-graph");
var graphList = graphmodule._list();
var dbList = db._listDatabases();
for (var j = 0; j < dbList.length; j++) {
if (dbList[j] == 'myapp')
db._dropDatabase('myapp');
}
db._createDatabase('myapp');
db._useDatabase('myapp');
db._create('appcoll'); // Collection already exists error occurs here
The collections that had previously been added to mydb remain in mydb, but they are empty. This isn't exactly a problem for my particular use case since the collections are empty and I had planned to rebuild them anyway, but I'd prefer to have a clean slate for testing and this behavior seems odd.
I've tried closing the shell and restarting the database between the drop and the add, but that didn't resolve the issue.
Is there a way to cleanly remove and re-add a database?
The collections should be dropped when db._dropDatabase() is called.
However, if you run db._dropDatabase('mydb'); directly followed by db._createDatabase('mydb'); and then retrieve the list of collections via db._collections(), this will show the collections from the current database (which is likely the _system database if you were able to run the commands)?.
That means you are probably looking at the collections in the _system database all the time unless you change the database via db._useDatabase(name);. Does this explain it?
ArangoDB stores additional information for managed graphs;
Therefore when working with named graphs, you should use the graph management functions to delete graphs to make shure nothing remains in the system:
var graph_module = require("org/arangodb/general-graph");
graph_module._drop("social", true);
The current implementation of the graph viewer in the management interface stores your view preferences (like the the attribute that should become the label of a graph) in your browsers local storage, so thats out of the reach of these functions.
Given the following code:
listView.ItemsSource =
App.azureClient.GetTable<SomeTable>().ToIncrementalLoadingCollection();
We get incremental loading without further changes.
But what if we modify the read.js server side script to e.g. use mssql to query another table instead. What happens to the incremental loading? I'm assuming it breaks; if so, what's needed to support it again?
And what if the query used the untyped version instead, e.g.
App.azureClient.GetTable("SomeTable").ReadAsync(...)
Could incremental loading be somehow supported in this case, or must it be done "by hand" somehow?
Bonus points for insights on how Azure Mobile Services implements incremental loading between the server and the client.
The incremental loading collection works by sending the $top and $skip query parameters (those are also sent when you do a query by using the .Take and .Skip methods in the table). So if you want to modify the read script to do something other than the default behavior, while still maintaining the ability to use that table with an incremental loading collection, you need to take those values into account.
To do that, you can ask for the query components, which will contain the values, as shown below:
function read(query, user, request) {
var queryComponents = query.getComponents();
console.log('query components: ', queryComponents); // useful to see all information
var top = queryComponents.take;
var skip = queryComponents.skip;
// do whatever you want with those values, then call request.respond(...)
}
The way it's implemented at the client is by using a class which implements the ISupportIncrementalLoading interface. You can see it (and the full source code for the client SDKs) in the GitHub repository, or more specifically the MobileServiceIncrementalLoadingCollection class (the method is added as an extension in the MobileServiceIncrementalLoadingCollectionExtensions class).
And the untyped table does not have that method - as you can see in the extension class, it's only added to the typed version of the table.