This is actually the first time I'm posting something here. The problem I have is driving me crazy since I know such functionality exists elsewhere.
I'm trying to find a way to create new tables on the fly on node js using sequelize without having to restart the database (a DB implemented with SQL).
Moreover, I also need to create new associations between those new table and existing ones.
Why do I need this:
I'm creating a crm and one of the functionalities I want to add is to let users create new types of objects that could have fields referencing to other preexisting ones.
And I can't just restart the whole database everytime a user is creating a new object or fields.
If you guys know how to achieve that or maybe advising me to build the database with another language I'll go for it.
Thanks!
Related
I want to store information in some activities that are modified versions of activities imported from an existing database (ecoinvent).
I know we can add fields to activities created from scratch (example). (I guess this is because the structure of the database has not yet been defined...) but is there a way of adding it to activities of an already defined database without breaking it?
The way around I found is to add entries to the author dict, which I can easily access later on. e.g.
act['author']['scenario']='myscenario'
but I admit it is not a very elegant solution.
You can just add whatever data you want. Brightway is a (semi-)schemaless database for exactly this reason.
act['foo'] = 'bar'
act.save()
I have a mongoose question that I'll try to form into something that makes sense. So, I have a User schema with a LOT of stuff in it.
Is there a way to create a new user without copying the entire schema in another file? So, just reference the schema and pass through values that are changed?
In past projects, everything in my schema also needed to be updated when creating users so that wasn't an issue.
User error on my part, I thought there was something wrong with everything except my forgetfulness. Long story short, I added a new partial template to my project and was getting the email via input[type=email]. The partial added a second one so the email parameter was never received by the backend.
Whoops.
https://azure.microsoft.com/en-us/documentation/articles/mobile-services-dotnet-backend-use-existing-sql-database/
I have been following this tutorial but it ends up creating a new table emptying all the data. How do I make it uses existing values inside an existing table?
The tutorial indeed populate example data using Database.SetInitializer(new ExistingInitializer()); but it wont make new DB.
Make sure you have correct connection string Name=MS_TableConnectionString (step 4 in Exploring the existing database model) so it points out to you existing DB
Edit:
First of all, comment out database seeder Database.SetInitializer(new ExistingInitializer()); and to query your existing data use GetAllMobileCustomers in MobileCustomerController or GetAllMobileOrders in MobileOrderController it will give you IQueryable of MobileCustomer of MobileOrder object, use that object as you wish
I'm developing an ASP.NET MVC 4.5 project using EF 6 Code First to an Existing Database. I would like to create some new tables with foreign key relationships to one of the tables in the dbcontext I've created. I've altered and added columns in that original table, creating several migrations. There is real data in that table.
I would prefer to create the new tables in the database, but don't see how EF would generate a model for me. I can code the model myself, but don't see any documentation about how I would add it to the context class generated by EF. And then the migrations would be out of whack.
So I'm thinking that the best thing to do would be to delete all the migrations, delete the context class and drop the migrations table. Then I could start from scratch with an initial migration. Am I missing some gotcha? Is there a better way?
FWIW to others facing this dilemma, I figured it out. First I got rid of all the migrations, following the 100+ up-voted answer here: Reset Entity-Framework Migrations
Second, I created new the tables and constraints I needed in the database.
Third, I created a new entity in my solution and generated model classes from the database. I changed calls from the old entity to the new entity.The generator overwrote the model for the original table, but since I have all the annotations in version control, it is trivial to paste them in.
If I need to, I can enable migrations again.
Hope this helps.
I am looking at the documentation for Meteor and it gives a few examples. I'm a bit confused about two things: First, where do you build the db (keeping security in mind)? Do I keep it all in the server/private folder to restrict client-side access? And second, how do I define the structure? For example, the code they show:
Rooms = new Meteor.Collection("rooms");
Messages = new Meteor.Collection("messages");
Parties = new Meteor.Collection("parties");
Rooms.insert({name: "Conference Room A"});
var myRooms = Rooms.find({}).fetch();
Messages.insert({text: "Hello world", room: myRooms[0]._id});
Parties.insert({name: "Super Bowl Party"});
I don't understand how a collection's structure is defined. Are they just able to define a collection and throw arbitrary data into it?
To answer your first question about where to put the new Meteor.Collection statements, they should go in a .js file in a folder accessible by both client and server, such as /collections. (With some exceptions: any collections that are never synced to the client, like server logs, should be defined inside /server somewhere; and any local collections should be defined in client code.)
As for your second question about structure: MongoDB is a document database, which by definition has no structure. Per the docs:
A database holds a set of collections. A collection holds a set of
documents. A document is a set of key-value pairs. Documents have
dynamic schema. Dynamic schema means that documents in the same
collection do not need to have the same set of fields or structure,
and common fields in a collection’s documents may hold different types
of data.
You may also have heard this called NoSQL. Each document (record in SQL parlance) can have different fields. Hence, there's no place where you define initial structure for a collection; each document gets its "structure" defined when it's inserted or updated.
In practice, I like to create a block comment above each new Meteor.Collection statement explaining what I intend the structure to be for most or all documents in that collection, so I have something to refer to later on when I insert or update the collection's documents. But it's up to me in those insert or update functions to follow whatever structure I define for myself.
A good practice would probably be defining your collection on both client and server with a single bit of javascript code. In other words, put the following
MyCollection = new Meteor.Collection("rooms");
// ...
anywhere but neither in the client nor in the server directory. Note that this directive alone does not expose any sensitive data to nobody.
A brand new meteor project would contain by default the insecure and autopublish packages. The former will basically allow any client to alter your database in every possible way, i.e. insert, update and remove documents. The latter will make sure that all database content is published to everyone, no matter how ridiculously this may sound. But fear not! Their only goal is to simplify the development process at the very early stage. You should get rid of these to guys from your project as soon as you start considering security issues of any kind.
As soon as the insecure package is removed from your project you can control the database privileges by defining MyCollection.allow and MyCollection.deny rules. Please check the documentation for more details. The only thing I would like to mention here is that this code should probably be considered as a sensitive one, so I guess you should put it into your server directory.
Removing the autopublish package has effect on the set of data that will be sent to your clients. Again you can control it and define privilages of your choice by implementing a custom Meteor.publish routine. This is all documented here. Here, you have no option. The code can only run in the server environment, so the best choice would be to put it in the server directory.
About your second question. The whole buzz about NoSQL databases (like mongodb) is to put as few restrictions on the structure of your database as possible. In other words, how the collections are structured is only up to you. You don't have to define no models and you can change the structure of your documents (and or remove fields) any time you want. Doesn't it sound great? :)