Entities relationships and actions: how to model a resource creation that depends on another entity?
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Fabio Oliveira
Jan 11, 2017, 4:11:10 AM1/11/17
to Siren Hypermedia
Hi all,
What looks ok-ish, but than how to describe what attribute should be considered the id in the related entity? I can do it by convention, forcing to always have a attribute with the name "id" as the json:api does, or I can add a metadata section to my entity describing that.
Thanks all and specially Kevin for this amazing project, I am working in a internal project and we decided to go full power into the direction of a Restful interface, and after some research our specification of choice to help us to model our API is Siren.
But I would like some advice from the experts here. Probably my problem was already solved many times by you so probably you already have some best practices. I have an entity like this:
{
"class": [
"list"
],
"entities": [
{
"class": [
"cardSetup"
],
"rel": [
"item"
],
"properties": {
"name": "NFC_virtual_card_CH"
},
"entities": [
{
"rel": [
"paymentCard"
],
"href": "/admin/brands/mywirecard2go/model/payment-cards/NFC_virtual_card_CH",
"title": "Payment Card"
}
]
}
],
"actions": [
{
"name": "create",
"method": "POST",
"href": "/admin/brands/mywirecard2go/model/card-setups",
"type": "application/vnd.wirecard.brand.admin-v1+json"
}
],
"links": [
{
"rel": [
"self"
],
"href": "/admin/brands/mywirecard2go/model/card-setups"
}
]
}Basically as now the entity has a name and an associated entity to it. What I would like to know is how are you guys doing to model the actions to allow, in a machine-understandable way, to create a new entity associated with another already existing entity, how to update, etc...
A friend of us from the siren4j project added some custom attributes to fields, some of them make a lot sense for me, but I would like to discuss how this is seen by the fathers of the specification. For example the "options" attribute or the "optionsURL", see some of the documentation here: https://github.com/eserating/siren4j/wiki/Siren4JAnnotations.
From what I understood I could add in my create action something like that:
...
"fields":[
{
"name": "paymentCard",
"optionsURL": "/admin/brands/mywirecard2go/model/payment-cards" }
...
]
...What looks ok-ish, but than how to describe what attribute should be considered the id in the related entity? I can do it by convention, forcing to always have a attribute with the name "id" as the json:api does, or I can add a metadata section to my entity describing that.
But none of than, the fields above and my solution with metadata is described by the specification, so looks like I am taking the wrong direction, can you help me clarifying or giving some examples of similar problems solved by you?
Thanks!
Kevin Swiber
Jan 23, 2017, 2:05:11 PM1/23/17
to Siren Hypermedia
Hey Fabio,
Thanks for the kind words! I apologize for the delayed response.
I think there are a few potential solutions here.
I often use application/www-form-urlencoded request bodies, which gel nicely with Siren's HTML5 input field types. To maintain an association, I often toss a pointer into a hidden field (e.g., { "name": "parent-id", "type": "hidden", "value": 12345 }). The benefit here is that the client has to do nothing outside of the Siren hypermedia spec.
If you're using a non-default encoding type, you may have to bake that processing instruction into your custom media type documentation (application/vnd.wirecard.brand.admin-v1+json).
In either case, it's helpful to know the association token (perhaps an ID) beforehand. It seems like options and optionsURL are for providing a "radio button" style selection. Is that more of what you're going for?
Best Regards,
Kevin
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Tom Howard
Jan 24, 2017, 3:18:27 PM1/24/17
to Siren Hypermedia
Hi Fabio,
I would model each payment card as a factory and have the creation actions on it. e.g.
{ "class": [ "paymentCard" ], "properties": { "name": "NFC_virtual_card_CH" }, "actions": [ { "name": "create", "method": "POST", "href": "/admin/brands/mywirecard2go/model/payment-cards/NFC_virtual_card_CH" } ], "links": [ { "rel": [ "self" ], "href": "/admin/brands/mywirecard2go/model/payment-cards/NFC_virtual_card_CH" } ]}I would also model /admin/brands/mywirecard2go/model/payment-cards as a collection, so it would give me a list of payment cards I can create. e.g.
{ "class": [ "list" ], "properties": { "count": 1 }, "entities": [ { "class": [ "paymentCard" ], "rel": [ "item" ], "properties": { "name": "NFC_virtual_card_CH" }, "actions": [ { "name": "create", "method": "POST", "href": "/admin/brands/mywirecard2go/model/payment-cards/NFC_virtual_card_CH" } ], "links": [ { "rel": [ "self" ], "href": "/admin/brands/mywirecard2go/model/payment-cards/NFC_virtual_card_CH" } ] } ], "actions": [ { "name": "search", "method": "GET", "href": "/admin/brands/mywirecard2go/model/payment-cards", "fields": [ { "name": "q", "type": "text" } ] } ], "links": [ { "rel": [ "self" ], "href": "/admin/brands/mywirecard2go/model/payment-cards" }, { "rel": [ "first" ], "href": "/admin/brands/mywirecard2go/model/payment-cards" }, { "rel": [ "last" ], "href": "/admin/brands/mywirecard2go/model/payment-cards" } ]}Reply all
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