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0 pointsjmull1y ago0 comments

json merge patch is pretty good. I think it just needs an optional extension to specify an alternative magical value for “delete”. null is a pretty good default, and comports well with typical database patterns, but is outright bad for some things.

I think it also needs a “replace” option at the individual object update level. Merge is a good default, but the semantics of the data or a particular update could differ.

You’re almost surely doing something wrong if replace doesn’t work for arrays. I think the missing thing is a collection that is both ordered and keyed (often not by the same value). JSON by itself just doesn’t do that.

So maybe what’s missing is a general facility for specifying metadata on an update, which can be used to specify the magical delete value, and the key/ordering field for keyed, ordered collections.

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3 comments · 2 top-level

throwway1203851y ago· 1 in thread

> You’re almost surely doing something wrong if replace doesn’t work for arrays. I think the missing thing is a collection that is both ordered and keyed (often not by the same value). JSON by itself just doesn’t do that.

Yeah, you could assign an identity value to each element of the array and then use a subresource to manipulate those elements by identity value. Then you could PUT using the same JSON merge mechanism to clear individual fields, and you could DELETE to remove items from the array by subresource.

This just seems like a reinvention of a crufty piece of XML.

jmullOP1y ago

I just mean a mechanism for specifying metadata, and a little metadata.

Off the top of my head, an optional header like "MergeMetadataObjectPropertyName: @mergeMetadata"

Which would cause objects in the merge containing the property "@mergeMetadata" to be treated specially.

The merge meta data could (optionally) specify an alternative to null for the special delete value. Or (optionally) specify the key value for an array representing an ordered, keyed collection. (Or, possibly, to specify the order value for an object used to represent a keyed, ordered collection.)

I guess you could just do without the header and specify the metadata using magic values (in the same way null is used as a special value meaning delete), but it seems better to opt in to things things like that.

(IMO, json merge patch would have been slightly better if it had no special values by default, but it's not bad. "null means delete" is a small thing, you probably need delete regardless, and, anyway, the ship has sailed on that one.)

skrebbel1y ago

Once you add all that, it loses "no need to learn something new". At that point, I think I'd just go with JSON Patch which solves all of these, and more.

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