There is a table named house which has many-to-many association with location table. Have to sort the list by the value of the location.street. Is there a way to sort the result of the query according to the value of the populated field?
I tried:
House.populateAll().sort("location.street ASC").exec(console.log);
Neither waterline (0.10.22) or sailsjs (v0.11) currently support this.
You would need to process your return variable to reorder the data.
There is a ticket for this at https://github.com/balderdashy/waterline/issues/334
Related
The application we're designing has a function where users can dynamically add new elements to an entity that then need to be efficiently searched. The number of these elements is essentially unlimited. Our team has been looking at DynamoDB as a data store option, and we've been wrestling with the key/value model and how to get this dynamic data under an index for efficient querying.
I think I have a single-table solution that handles the problem elegantly and also allows for querying on any given attribute in the data store, but am disturbed that I can't find an example of it anywhere else. Hopefully it's not fundamentally flawed in some way - I would appreciate any critique!
The model is essentially the Entity-Attribute-Value approach used for adding dynamic or sparse data to RDBMs. So instead of storing different entities/objects in a DynamoDB table like so:
PK SK SK-1 SK-2 SK-3 SK-N... PK SK SK-1 SK-N...
Key Key Key Key --> Name Money
Entity Id Value Value Value Value Person 22 Fred 30000
... which lets me query things like "all persons where name = Fred" but where you would eventually run out of sort key indexes and you would need to know which index goes with which key before you query, the data could be stored in EAV format like so:
PK SK & GSI-PK GSI-SK PK SK & GSI-PK GSI-SK
Id Entity#Key Value 22 Person#Name Fred
Id Entity#Key Value --> 22 Person#Money 30000
Id Entity#Key Value 22 Person#Sex M
Id Entity#Key Value 22 Person#DOB 09/00
Now, with one global secondary index (GSI-1 PK over Entity.Key and GSI-1 SK over Value) I can do a range search on any value for any key and get a list of Ids that match. Users can add their attributes or even entirely new entities and have them persisted in a way that's instantly indexed without us having to revamp the DynamoDB schema.
The one major downside to this approach that I can think of is that data returned from a query on an Entity#Key-Value only contains values for that key and the entity Id, not the entire entity. That's fine for charts and graphs but a problem if you want to get a grid-type result with one query. I also worry about hot partition keys on the index, but hopefully we could solve that with intelligent write sharding.
That's pretty much it. With a few tweaks the model can be extended to support the logging of all changes on each key and allow some nice time series queries against those changes, but my question is if anyone has found it useful to take an EAV type approach to a KV store like DynamoDB, or if there's another way to handle querying a dynamic schema?
You can have pk as the id of the entity. And then a sort key of {attributeName}. You may still want to have the base entity with fields like createdAt, etc.
So you might have:
PK SORT Attributes:
#Entity#22 #Entity#Details createdAt=2020
#Entity#22 #Attribute#name key=name value=Fred
#Entity#22 #Attribute#money key=money value=30000
To get all the attributes of an entity you simply do a query with no filter of pk={id}. You cannot dynamically sort by every given attribute, this is exactly what DynamoDB is not good at, I repeat! That case is exactly what NOSQL performs poorly at.
What you can do is use streaming to do aggregation. So you can for instance store the top 10 wealthiest people:
PK SORT Attributes:
#Money#Highest #1 id=#Entity#22 value=30000
#Money#Highest #2 id=#Entity#52 value=30000
Which you would calculate in a DynamoDB Streams. But you couldn't dynamically index values, DynamoDB works by effectively copying data from one form to another so that it can be efficiently retrieved. So you would be copying your entire database for each new attribute you wanted to search by, or otherwise you would have to use Scans and that wouldn't make any sense to do because you would get no benefit to using DynamoDB if all you ever did was do Scans all the time.
Your processes need to be very well understood to make good use of DynamoDb, if you want to index data at will, and do all sorts of different queries, you probably want an SQL database or elasticsearch.
Does anyone know if there is a wildcard character in AppMaker that can be used for all possible values for a field in a query?
I currently have a datasource that is being filtered based on the status using a multi-select widget. What I would like to accomplish is when all values have been de-selected I want to load all the records of that datasource without clearing the entire query in case other filters have been applied. I have it working in-a-sense that I have to explicitly construct my query as such:
widget.datasource.query.filters.Status._in = ['Status Value 1','Status Value 2','Status Value 3']
My current solution is loading the correct data when a value is selected and it correctly shows the union of the query as the values are modified. However, it selects all of the values in my multi-select; which I know is how it is supposed to work.
I tried using widget.datasource.query.filters.Status._contains = ''; and changing the assignment value to no avail. I even tried the opposite approach using _notContains
The intended outcome is to have a filtering dashboard appear much like any website where when no filtering is selected all records are displayed. I was hoping to find a wildcard character that would load all of the records. Just trying to find a way to mimic other website filters with all records when none are selected.
Thanks for the time!
So the easiest solution here is to set up your Multiselect as follows:
Options binding:
#models.YourModel.fields.Status.possibleValues
or if you don't have the possible Status values in your model then set your options binding to:
['Status Value 1','Status Value 2','Status Value 3']
Values binding:
#datasource.query.filters.Status._in
Now anytime you select any choices in the multiselect, the query will only include records that include the selected choices. And if you deselect all choices the query will ignore that filter or treat it as an empty array of values, therefore returning all records unless you applied other filters.
Hi I'm trying to get a sorted Collection from the Domino Rest Api. My database name is "Test/JSON_Views.nsf" and my views name "List".
The endpoint I use is
**/Test/JSON_Views.nsf/api/data/collections/name/List?sortcolumn=title&sortorder=ascending&count=20
But the JSON-Response entries aren't sorting by title in ascending order.
Should I make any settings to the column properties in the designer? If I set descending there for the title-column it works. But I want to change the sorting in my external java-application.
Is my endpoint correct? I use this Domino API Docu as Reference.
Add an additional sorting to your title column:
This gives the API the possibility to sort by title in both directions. You can do this with other columns too so you are very flexible in sorting this way.
The doc says that if the column isn't sorted in design then the sortcolumn parameter has no effect, so the answer is "Yes" you should change the design of the desired column. If doing that is unworkable in whatever context you use it, then create a second view and use that instead.
I am querying a Model*, which has a field that refers to another Model. Is it possible to order the results using a field in the linked Model?
So for example:
Car contains a field which refers to its OWner. I want to show all Cars sorted by their owner.
(I don't want to use the statement() method since in that case I would have to write the whole query myself)
(*) using http://typo3.org/api/typo3cms/class_t_y_p_o3_1_1_c_m_s_1_1_extbase_1_1_persistence_1_1_generic_1_1_query.html
Yes, it is possible (don't care for the $constraint for the moment):
$query->matching($constraint)->setOrderings(
array('owner.sorting' => Tx_Extbase_Persistence_QueryInterface::ORDER_ASCENDING)
)->execute();
Assuming the field in you Car model is named owner and you want to sort by sorting field of the Owner model/table.
When working with 6.2
->setOrderings(Array('model.yourfield' => \TYPO3\CMS\Extbase\Persistence\QueryInterface::ORDER_ASCENDING))
#Michael and #rob-ot are right. There is one pitfall that took me many hours and that I'd like to mention here:
If your sort field in your related table contains underscores, you have to provide its name to setSortOrderings in lowerCamelCase:
// with database column name my_car_sorting you must define:
$query->matching($constraint)->setOrderings(
array('owner.myCarSorting' => \TYPO3\CMS\Extbase\Persistence\QueryInterface::ORDER_ASCENDING)
)->execute();
How can we replicate the following sql query in MongoDb?
update Person set Alias = Name;
where the Person table has the columns Alias, Name
I want the query to affect multiple rows. It doesn't matter if the update query cannot support upserts, I only need to update & not insert.
Unfortunately, that functionality is not available in MongoDB. You will need to loop through the documents, updating them one-at-a-time, and doing a read-update pair.
If you want this to be concurrency-safe, you'll need to implement some sort of locking; either optimistic or pessimistic.
myDb.myCollection.find({}).forEach(
function (person) {
person.Alias = person.Name
myDb.myCollection.save(person)
}
)