I need to call a collection consisting of objects that have an un-empty array in the items (array) field, I filter collection like this:
filter:
conditions:[
{
property: "items",
operator: "notEmpty",
value:null
}]
but this solution doesn't work, 500 error is returned, how to implement it?
CUBA Platform REST API doesn't support filtration by collections (#OneToMany and #ManyToMany relations).
To implement such functionality you need to create and expose predefined JPQL query on back end.
There is similar discussion on CUBA Platform forum.
Related
Is it possible to limit API response from the POST /item/app/{app_id}/filter/ for a complex resources with a lot of fields set? I know there is fields param and it can be used with some predefined views, like items.view(micro), but this is not a solution for us. We need to explicitly define which fields should be returned, to have in the response only needed fields (optimize the output length as much as possible, but have all needed fields). Can we somehow achieve this by available for now API params or could Podio consider to introduce such functionality in the future API revisions?
You can specify the fields() decorator, to add desired fields to your view.
items.view(micro).fields(fields,created_on,last_edit_on)
Unfortunately I don't think it is possible to further filter the number of Podio Application's Fields returned under the REST response's fields field (ugh 😓).
I couldn't find a way to filter on the Fields defined by the user on the Application.
E.g.
[
{
"fields": [
{
"label": "My item field"
"field_id": 123456778,
"external_id": "my-item-field"
}
]
}
]
It's not possible to filter by my-item-field.
As I know, Rest Api doesn't allow you to limit (select) output fields. (As GraphQL can do)
So, while Podio is on Rest Api - you can't do that.
This question is language independent. Let's not worry about frameworks or implementation, let's just say everything can be implemented and let's look at REST API in an abstract way. In other words: I'm building a framework right now and I didn't see any solution to this problem anywhere.
Question
How one can construct REST URL endpoint for intersection of two independent REST paths which return collections? Short example: How to intersect /users/1/comments and /companies/6/comments?
Constraint
All endpoints should return single data model entity or collection of entities.
Imho this is a very reasonable constraint and all examples of Hypermedia APIs look like this, even in draft-kelly-json-hal-07.
If you think this is an invalid constraint or you know a better way please let me know.
Example
So let's say we have an application which has three data types: products, categories and companies. Each company can add some products to their profile page. While adding the product they must attach a category to the product. For example we can access this kind of data like this:
GET /categories will return collection of all categories
GET /categories/9 will return category of id 9
GET /categories/9/products will return all products inside category of id 9
GET /companies/7/products will return all products added to profile page of company of id 7
I've omitted _links hypermedia part on purpose because it is straightforward, for example / gives _links to /categories and /companies etc. We just need to remember that by using hypermedia we are traversing relations graph.
How to write URL that will return: all products that are from company(7) and are of category(9)? In otherwords how to intersect /categories/9/products and /companies/7/products?
Assuming that all endpoints should represent data model resource or collection of them I believe this is a fundamental problem of REST Hypermedia API, because in traversing hypermedia api we are traversing relational graph going down one path so it is impossible to describe such intersection because it is a cross-section of two independent graph paths.
In other words I think we cannot represent two independent paths with only one path. Normally we traverse one path like A->B->C, but if we have X->Y and Z->Y and we want all Ys that come from X and Z then we have a problem.
So far my proposition is to use query strings: /categories/9/products?intersect=/companies/9 but can we do better?
Why do I want this?
Because I'm building a framework which will auto-generate REST Hypermedia API based on SQL database relations. You could think of it as a trans compiler of URLs to SELECT ... JOIN ... WHERE queries, but the client of the API only sees Hypermedia and the client would like to have a nice way of doing intersections, like in the example.
I don't think you should always look at REST as database representation, this case looks more of a kind of specific functionality to me. I think I'd go with something like this:
/intersection/comments?company=9&product=5
I've been digging after I wrote it and this is what I've found (http://www.vinaysahni.com/best-practices-for-a-pragmatic-restful-api):
Sometimes you really have no way to map the action to a sensible RESTful structure. For example, a multi-resource search doesn't really make sense to be applied to a specific resource's endpoint. In this case, /search would make the most sense even though it isn't a resource. This is OK - just do what's right from the perspective of the API consumer and make sure it's documented clearly to avoid confusion.
What You want to do is to filter products in one of the categories ... so following Your example if we have:
GET /categories/9/products
Above will return all products in category 9, so to filter out products for company 7 I would use something like this
GET /categories/9/products?company=7
You should treat URI as link to fetch all data (just like simple select query in SQL) and query parameters as where, limit, desc etc.
Using this approach You can build complex and readable queries fe.
GET /categories/9/products?company=7&order=name,asc&offset=10&limit=20
All endpoints should return single data model entity or collection of
entities.
This is NOT a REST constraint. If you want to read about REST constraints, then read the Fielding dissertation.
Because I'm building a framework which will auto-generate REST
Hypermedia API based on SQL database relations.
This is a wrong approach and has nothing to do with REST.
By REST you describe possible resource state transitions (or operation call templates) by sending hyperlinks in the response. These hyperlinks consist of a HTTP methods and URIs (and other data which is not relevant now) if you build the uniform interface using the HTTP and URI standards, and we usually do so. The URIs are not (necessarily) database entity and collection identifiers and if you apply such a constraint you will end up with a CRUD API, not with a REST API.
If you cannot describe an operation with the combination of HTTP methods and already existing resources, then you need a new resource.
In your case you want to aggregate the GET /users/1/comments and GET /companies/6/comments responses, so you need to define a link with GET and a third resource:
GET /comments/?users=1&companies=6
GET /intersection/users:1/companies:6/comments
GET /intersection/users/1/companies/6/comments
etc...
RESTful architecture is about returning resources that contain hypermedia controls that offer state transitions. What i see here is a multistep process of state transitions. Let's assume you have a root resource and somehow navigate over to /categories/9/products using the available hypermedia controls. I'd bet the results would look something like this in hal:
{
_links : {
self : { href : "/categories/9/products"}
},
_embedded : {
item : [
{json of prod 1},
{json of prod 2}
]
}
}
If you want your client to be able to intersect this with another collection you need to provide to them the mechanism to perform this. You have to give them a hypermedia control. HAL only has links, templated links, and embedded as control types. let's go with links..change the response to:
{
_links : {
self : { href : "/categories/9/products"},
x:intersect-with : [
{
href : "URL IS ABSOLUTELY IRRELEVANT!!! but unique 1",
title : "Company 6 products"
},
{
href : "URL IS ABSOLUTELY IRRELEVANT!!! but unique 2",
title : "Company 5 products"
},
{
href : "URL IS ABSOLUTELY IRRELEVANT!!! but unique 3",
title : "Company 7 products"
}
]
},
_embedded : {
item : [
{json of prod 1},
{json of prod 2}
]
}
}
Now the client just picks the right hypermedia control (aka link) based on the title field of the link.
That's the simplest solution. But you'll probably say there's 1000's of companies i don't want 1000's of links...well ok if that;s REALLY the case...you just offer a state transition in the middle of the two we have:
{
_links : {
self : { href : "/categories/9/products"},
x:intersect-options : { href : "URL to a Paged collection of all intersect options"},
x:intersect-with : [
{
href : "URL IS ABSOLUTELY IRRELEVANT!!! but unique 1",
title : "Company 6 products"
},
{
href : "URL IS ABSOLUTELY IRRELEVANT!!! but unique 2",
title : "Company 5 products"
},
{
href : "URL IS ABSOLUTELY IRRELEVANT!!! but unique 3",
title : "Company 7 products"
}
]
},
_embedded : {
item : [
{json of prod 1},
{json of prod 2}
]
}
}
See what i did there? an extra control for an extra state transition. JUST LIKE YOU WOULD DO IF YOU HAD A WEBPAGE. You'd probably put it in a pop up, well that's what the client of your app can do too with the result of that control.
It's really that simple...just think how you'd do it in HTML and do the same.
The big benefit here is that the client NEVER EVER needed to know a company or category id or ever plug that in to some template. The id's are implementation details, the client never knows they exist, they just executed Hypermedia controls..and that is RESTful.
I have a document in RavenDB that looks looks like:
{
"ItemId": 1,
"Title": "Villa
}
With the following metadata:
Raven-Clr-Type: MyNamespace.Item, MyNamespace
Raven-Entity-Name: Doelkaarten
So I serialized with a type MyNamespace.Item, but gave it my own Raven-Entity-Name, so it get its own collection.
In my code I define an index:
public class DoelkaartenIndex : AbstractIndexCreationTask<Item>
{
public DoelkaartenIndex()
{
// MetadataFor(doc)["Raven-Entity-Name"].ToString() == "Doelkaarten"
Map = items => from item in items
where MetadataFor(item)["Raven-Entity-Name"].ToString() == "Doelkaarten"
select new {Id = item.ItemId, Name = item.Title};
}
}
In the Index it is translated in the "Maps" field to:
docs.Items
.Where(item => item["#metadata"]["Raven-Entity-Name"].ToString() == "Doelkaarten")
.Select(item => new {Id = item.ItemId, Name = item.Title})
A query on the index never gives results.
If the Maps field is manually changed to the code below it works...
from doc in docs
where doc["#metadata"]["Raven-Entity-Name"] == "Doelkaarten"
select new { Id = doc.ItemId, Name=doc.Title };
How is it possible to define in code the index that gives the required result?
RavenDB used: RavenHQ, Build #961
UPDATE:
What I'm doing is the following: I want to use SharePoint as a CMS, and use RavenDB as a ready-only replication of the SharePoint list data. I created a tool to sync from SharePoint lists to RavenDB. I have a generic type Item that I create from a SharePoint list item and that I serialize into RavenDB. So all my docs are of type Item. But they come from different lists with different properties, so I want to be able to differentiate. You propose to differentiate on an additional property, this would perfectly work. But then I will see all list items from all lists in one big Items collection... What would you think to be the best approach to this problem? Or just live with it? I want to use the indexes to create projections from all data in an Item to the actual data that I need.
You can't easily change the name of a collection this way. The server-side will use the Raven-Entity-Name metadata, but the client side will determine the collection name via the conventions registered with the document store. The default convention being to use the type name of the entity.
You can provide your own custom convention by assigning a new function to DocumentStore.Conventions.FindTypeTagName - but it would probably be cumbersome to do that for every entity. You could create a custom attribute to apply to your entities and then write the function to look for and understand that attribute.
Really the simplest way is just to call your entity Doelkaarten instead of Item.
Regarding why the change in indexing works - it's not because of the switch in linq syntax. It's because you said from doc in docs instead of from doc in docs.Items. You probably could have done from doc in docs.Doelkaartens instead of using the where clause. They are equivalent. See this page in the docs for further examples.
I am wondering if it is possible to map a named native query on the fly instead of getting back a list of Object[] and then looping through and setting up the object that way. I have a call which I know ill return a massive data set and I want to be able to map it right to my entity. Can I do that or will I have to continue looping through the result set.
Here is what I am doing now...
List<Provider> ObjList = (List<Provider>) emf.createNativeQuery(assembleQuery(organizationIDs, 5)).getResultList();
That is my entity, the List (my entity is the provider). Normally I would just return a List<Object[]>
and then I would loop through that to get back all the objects and set them up as new providers and add them to a list....
//List<Provider> provList = new ArrayList<Provider>();
/*for(Object[] obj: ObjList)
{
provList.add(this.GetProviderFromObj(obj));
}*/
As you can see I commented that section of the code out to try this out. I know you can map named native queries if you put your native query in the entity itself and then call it via createNamedQuery. I would do it that way, but I need to use the IN oracle keyword because I have a list of ID's that I want to check against. It is not just one that is needed. And as we all know, native queruies don't handle the in keyword to well. Any advice?
Sigh, If only the IN keyword was supported well for NamedNativeQueries.
Assuming that Provider is configured as a JPA entity, you should be able to specify the class as the second parameter to your createNativeQuery call. For example:
List<Provider> ObjList = (List<Provider>) emf.createNativeQuery(assembleQuery(organizationIDs, 5), Provider.class).getResultList();
According to the documentation, "At a minimum, your SQL must select the class' primary key columns, discriminator column (if mapped), and version column (also if mapped)."
See the OpenJPA documentation for more details.
I'm designing a new API for my project, and I want to return objects that have nested children as json. For that purpose i've decided to use RABL.
I want the client side to be able to understand whether the object is valid, and if not which fields are missing in order to save it correctly.
The design I thought of should include some fields as optional, under an optional hash, and the rest are required. The required fields should appear right under the root of the json.
So the output I try to describe should look something like this:
{
"name": "John",
"last_name": "Doe",
"optional": {
"address": "Beverly Hills 90210",
"phones":[{"number":"123456","name":"work"}, {"number":"654321","name":"mobile"}]
}
}
The above output example describes the required fields name and last name, and the not required address and phones (which is associated in a belongs_to-has_many relationship to the object). name, last_name and address are User's DB fields.
Playing with RABL I didn't manage so far to create this kind of structure.
Any suggestions? I'm looking for a DRY way to implement this for all my models.
RABL is really good in creating JSON structures on the fly, so I don't see why you couldn't achieve your goal. Did you try testing if a field is set to null-able in the schema, and thus presenting it as optional? It seems a good approach for me. For the nested children, just do the same, but extend the template for the children.
For example, in your father/show.rabl display a custom node :optional with all the properties that can be null.
Then, create a child/show.rabl with the same logic. Finally, go back to father/show.rabl and add a child node, extending the child/show.rabl template. This way you could achieve unlimited levels of "optionals".
Hope it helped you.
In this case I'd use the free form option.
From https://github.com/nesquena/rabl
There can also be odd cases where the root-level of the response
doesn't map directly to any object.
In those cases, object can be assigned to 'false'
and nodes can be constructed free-form.
object false
node(:some_count) { |m| #user.posts.count }
child(#user) { attribute :name }