I have accidentally created hundreds of columns in my User class. Can anyone tell me how to easily delete a number of columns? Currently the only way I can delete them is individually through the Parse online interface.
You can use the Schema API to delete columns from your collection, check the documentation for details. A good strategy might be to fetch a list of columns the collection you want to modify has, create a list of columns you want to keep and then delete each column that is not in this list.
Related
I want to work with Elasticsearch to process some Whatsapp chats. So I am initially planning the data load.
The problem is that the data exported from Whatsapp, doesn't contain a real unique id per user but it only contains the name of the user taken from the contact directory of the device where the chat is exported (ie. a user can change the number or have two numbers in the same group).
Because of that, I need to create a custom explicit mapping table between the user names and a self-generated unique id, that gets populated in an additional column.
Then, my question is: "How can I implement such kind of explicit mapping in Elasticsearch to generate an additional unique column?". Alternatively, a valid answer could be a totally different approach to the problem.
PS. As I write, I think the solution could be in the ingestion process, like in a python script, but I still want to post the question to understand if this is something that Elasticsearch can do by itself.
yes, do it during the index process
if you had the data that maps the name and the id stored in a separate index you could do this with an enrich processor when you index the data to add whichever value you want to the document via a pipeline
also - Elasticsearch doesn't have columns, only fields
In Laravel Lighthouse GraphQL, I'd love to be able to delete records that match certain conditions rather than passing just an individual ID.
I get this error:
The #delete directive requires the field deletePostTag to only contain a single argument.
This functionality seems currently unsupported, but if I'm wrong and this is actually supported, please let me know, because this would be the most straightforward approach.
So then my second approach was to try to first run an #find query to retrieve the ID of the record that I want to delete (based on certain fields equaling certain values).
But https://lighthouse-php.com/4.16/api-reference/directives.html#find shows:
type Query {
userById(id: ID! #eq): User #find
}
and does not show how I could provide (instead of the primary key ID) 2 arguments: a foreign key ID, and a string.
How can I most simply accomplish my goal of deleting records that match certain conditions (rather than deleting via primary key)?
I'm not sure about the #delete functionality regarding multiple arguments, but from what you've posted that appears to be unsupported at the moment. Regarding your query, you should instead use something like #all in conjunction with #where which would allow you to filter the collection by as many vars/args as you'd like. If your argument list grows beyond 3 or so, I would take a look at Complex Where Conditions. They have worked very well for my team so far, and allow a lot of filtering flexibility.
Also take a look at the directive's docs stating:
You can also delete multiple models at once. Define a field that takes a list of IDs and returns a collection of the deleted models.
So if you return multiple models you'd like to delete from your query, you may use this approach to delete them all at once.
I am using typed datasets to retrieve and manipulate data. To generate a typed dataset I use the built-in dataset designer and drag-drop tables from data sources. In addition, mostly I need to add custom columns to my data tables.
The problem is that when I make a change in the underlying database schema I simply delete and regenerate the data table and loose all the custom columns that I added earlier. So everytime I regenerate a data table I had to add these custom columns again and again.
So my question is that if there is an easy way to mantain or keep track of these custom columns?
Don't delete the DataTable and regenerate it. Instead right-click, choose configure and adjust the query to add/remove your new columns. Then click finish and the table will be updated in the DataSet but without deleting your customisations.
How to do databse driveen jsp page,
Suppose i have 5 text fields,if user wants to put one of the form field as select box.JSp should identify and return the select box if it define in db as select box.
I dont know how to achieve this,can anyone suggest this.
Regards,
Raju komaturi
There are multiple tasks if you want to do this completely. The world at large has not gone this way and so there are not many tools (if any) for this. But basically here are the main ideas.
1) You want a "data dictionary", a collection of meta-data that tells you what the types and sizes of each column are, and the primary and foreign keys are.
2) For your example of "knowing" that a field should be a drop-down, this almost always means that column value is a foreign key to another table. Your code detects this and builds a listbox out of the values in the parent table.
3) You can go so far as to create a complete form generator for simple tables, where all of the HTML is generated, but you always need a way to override this for the more complex forms. If you do this, your data dictionary should also have column descriptions or captions.
There are many many more ideas, but this is the starting point for what you describe.
I am somewhat new to LINQ and have a quick question regarding deleting.
Say, for example I have 2 tables, Orders and OrderItems. Using LINQ, I can easily create a new child record by using
order.Items.Add(new OrderItem());
and this will create the child record in the database and update its foreign key to the orderId. This is great, I like it! However when I want to remove a child record
order.Items.Remove(orderItem);
I get an error when I sumbit the changes (because its not actually deleting the child row (order item), just removing the foreign keyId). Is it possible to do this the way I would like to? I don't want to have to create a whole bunch of repositories and if ladders to delete all child rows for a large database.
Thanks in advance.
E
You can achieve that in the DB itself by configuring the Foreign key relationship to delete child records on deletion of the parent's key.
Note that this is transparent to Linq2SQL and it will not be aware of it, so it's best to make sure you do not keep the datacontexts around after that, since the OrderItem objects will still be present.
Set ON DELETE CASCADE for the table in question which will let the SQL Server handle this for you.