I'm having some trouble getting relation deletion to work exactly how I would expect it to.
For example I have two simple tables, users and permissions with a one-to-many relation between users and permissions (or it could be many-to-many in this example as well).
I first tried deleting one of the related permissions using userDatasource.deleteItem() or userDatasource.item.permissions[index]._delete() but when you use either of those functions it marks the record as deleted client side so you run into trouble when you need to insert again.
I then found a related question that said to use item.relation.splice(startIndex, 1) to just break the relation and that worked as expected but now I have a bunch of extra rows in my database with the user foreign key null. I would much rather have the same behavior as .splice but also have it delete those records from the database. Is there any way to do that or is App Maker supposed to detect the broken relation and automatically delete the row from the table?
Just do a check after the splice like this:
if (item.relation.length === 0) {
item._delete();
}
Related
I have a use case where DynamoDB is running in production and I need to add a new column IDUpdatedAt which will also be serving as a sort key for one of the GSIs.
I tried a thing in test where my application adds the new rows with IDUpdatedAt, it's working fine but what about the existing rows? How to add the values for those?
Also the new rows will not be added without IDUpdatedAt, but how will the search be impacted for older rows?
PS: IDUpdatedAt is being used as a filter in the application, i.e., user can search for specific ID and can get results sorted by date. That's why IDUpdatedAt is also a part of GSI (sort key).
Please help.
You've got the right idea by adding the field to new items. After all, DynamoDB does not enforce a particular schema outside of the primary key.
This also happens to be a very useful feature, especially when defining a GSI on that attribute; if the atttibute exists on the item, it ends up in the index! For example, imagine modeling an email inbox in DDB where each item represents an email. You could include an attribute 'is_read' and define a GSI using that atttibute.
If the 'is_read' attribute exists on the item, it's in the index. Otherwise, it's not. A cool way to use GSIs to implement filtering.
Pretty neat stuff!
However, there is no way to retroactively update all items with a new attribute other than manually updating each item (or in batches). The equivalent in SQL databases is defining a new column. Unfortunately, an analogous operation in DDB does not exist.
I am creating a leave tracker app where I want to store the user ID along with the from date and to date. I am using Amazon's DynamoDB as the database, and the user enters a leave through a custom command.
Eg: apply-leave from-date to-date
I want to avoid duplicate entries in the database. For example, if a user has already applied for a leave between 06-10-2019 to 10-10-2019 and applies for a leave between the same dates again, they should get a message saying that this already exists and a new record should not be created for the same.
However, a user can apply for multiple leaves and two users can take a leave between the same dates.
I tried using a conditional statement as follows:
table.put_item(
Item={
'leave_id': leave_id,
'user_id': user_id,
'from_date': from_date,
'to_date': to_date,
},
ConditionExpression='attribute_not_exists(user_id) AND attribute_not_exists(from_date) AND attribute_not_exists(to_date)'
)
where leave_id is the partition key. However, this does not work and a new row is added every time, even if it is the same dates. I have looked through similar other questions, but haven't been able to understand how to get this configured correctly.
Any ideas on how I should go about this, or if there is a different design that I should follow?
If you are calling your code with the leave_id that doesn't yet exist in the table, the item will always be inserted. If you call your code with leave_id that does already exist in your table you should be getting An error occurred (ConditionalCheckFailedException) when calling the PutItem operation: The conditional request failed error message.
I have two suggestions:
If you don't want to change your table, you can create a secondary index with user_id as the partition key and then query the index for all the items where the given user has some from_date and to_date attributes.
Like this:
table.query(
IndexName='user_id-index',
KeyConditionExpression=Key('user_id').eq(user_id),
FilterExpression=Attr('from_date').exists() & Attr('from_date').exists()
)
Then you will need to check for overlapping leave requests, etc. (eg. leave request that starts before the one that is already in place finishes). After deciding that the leave request is a valid one you will call put_item.
Another suggestion and probably a better one would be to create a composite primary key on your table with user_id as a partition key and leave_id as a sort key. That way you could execute a query for all leave requests from a particular user without the need to create a secondary index.
Iterations of this question have been asked in the past, but this presents unique challenges as it combines some of the issues in one larger problem.
I have an entity(User) that is used as the user class in my application, then I have another entity (UserExtra), in a one-to-one relationship with the user entity, UserExtra's id is the same as User. The foreign key is the same as the primary key.
When the user object is loaded (say by $this->getUser() or by {{ app.user }}, the UserExtra data is also loaded through a join. The whole point of having two entities is so I don't have to load all the data at once.
I even tried defining a custom UserLoaderInterface/UserProviderInterface Repository for User, making sure that refreshUser and loadUserByUsername would only load the User data (I'd like for the UserExtra data to sit in a proxy unless I explicitly need it) but when Doctrine goes to Hydrate the object, it issues an extra query to load the UserExtra data, thereby skipping the Proxy status.
Is there a way out of this?
there are many solution for your issue:
1) Change the owning side and inverse side http://developer.happyr.com/choose-owning-side-in-onetoone-relation - I don't think that's right from a DB design perspective every time.
2) In functions like find, findAll, etc, the inverse side in OneToOne is joined automatically (it's always like fetch EAGER). But in DQL, it's not working like fetch EAGER and that costs the additional queries. Possible solution is every time to join with the inverse entity
3) If an alternative result format (i.e. getArrayResult()) is sufficient for some use-cases, that could also avoid this problem.
4) Change inverse side to be OneToMany - just looks wrong, maybe could be a temporary workaround.
5) Force partial objects. No additional queries but also no lazy-loading: $query->setHint (Query::HINT_FORCE_PARTIAL_LOAD, true) - seams to me the only possible solution, but not without a price:
Partial Objects are a little bit risky, because your entity behavior is not normal. For example if you not specify in ->select() all associations that you will user you can have an error because your object will not be full, all not specifically selected associations will be null
6) Not mapping the inverse bi-directional OneToOne association and either use an explicit service or a more active record approach - https://github.com/doctrine/doctrine2/pull/970#issuecomment-38383961 - And it looks like Doctrine closed the issue
this question may help you : one to one relation load
We created special form to creating purchase prices for vendors.
New form has almost the same fields as original (so we used PriceDiscTable), but the record/datasoruce was set as temporary table. After user filled mandatory fields will click button, (extra logic behind) and record will inster to database (real priceDiscTable).
The idea was to grand access to trade prices for users that not necessarily has access to purchase prices. In theory everything was ok, but when user with no access to PriceDiscTable open new form, error was shown "Not enougt right to use table 'Price agreements'".
We try set the AllowCheck to false in formDatasource but this only allow us to open the form, but user still cannot add or modify records.
Is there any way to force system to allow user to write data in the temporary table?
Disabling security key or grand access to real table is not an option.
Duplicate table and create with same fields is nuisance (if we use same table we can use data() method to assign fields)
I think that creating a new temporary table with [almost] the same fields would be the best solution.
If the only reason you oppose to this approach is that you wouldn't be able to use data() to copy data from one table to another you can use buf2BufByName() as described here: http://mybhat.blogspot.co.uk/2012/07/dynamics-ax-buf2buf-and-buf2bufbyname.html
You can use RunAs to impersonate another user...perhaps a system user. I don't entirely follow what you are trying to do, but it sounds like this solution would work for you if you know exactly what your custom code is doing and is capable of.
See Classes\AifOutboundProcessingService\runAsWrapper to see an example.
You will not be able to display the PriceDiscTable without giving the user at least "view" access or editing Classes\FormRun to somehow bypass the security key, which is kernel level so it's also not possible.
I agree with 10p where you should create a temp table and then create a custom method handler combined with buf2bufbyname() or buf2buf().
Another option you can screw around with, if you REALLY want to use .data() is using a Common as the datasource. You could add the fields you want on the grid with the common, then you can pass a common back/forth. This has a good amount of form setup to get this working, but it could produce what you want eventually I think.
static void Job8(Args _args)
{
Common common;
salesTable salesTable;
;
common = new DictTable(366).makeRecord();
select firstonly common where common.RecId == 5637145357;
salesTable.data(common);
info(strfmt("%1 - %2", salesTable.SalesId, salesTable.SalesName));
}
I've started porting a .NET SQL Server application to LINQ to Entities. I have (among others...) one table called Users, and one called Time. Time is reported on a specific user (UserId), but it is also recorded which user made the report (InsertedByUserId) and possibly who has updated the Time since insert (UpdatedByUserId). This gives me three references to the table Users.
When I generate a .EDMX from this I get three references to the table Users: User, User1 and User2. Without manual edit I have no way of knowing which one refers to the UserId, InsertedByUserId or UpdatedByUserId field.
How do others solve this? Maybe it's not necessary to register ALL references, and stick with InsertedByUserId and UpdatedByUserId as ints?
(The manual edit wouldn't be a problem if the database were never updated, but as we make changes to the database every now and then we occasionally have to regenerate the .EMDX, thus removing all manual changes.)
Thanks in advance!
Jos,
Generally when I make my foreign keys, I name them accordingly. From the Entity designer you can differentiate between the different Navigation Properties (ie User, User1, User2) by looking at the FK association (as long as you named your foreign keys distinctly). For Instance I have a ModifiedById and CreatedById field in each table. Both fields reference my SystemUser table, My foreign keys are named like this: FK_[TableName]_SystemUser_CreatedBy and FK_[TableName]_SystemUser_ModifiedBy.
You should notice that in the Navigation properties you can see the Foreign key. You can also modify the name of the Navigation Property (which is in the Conceptual Side "CSDL portion" of the EDMX), and this change will stay when you update your EDMX from the database.