Re: Context lenses to set/get values in json values.

On 10/08/2014 12:13 PM, Paweł Cesar Sanjuan Szklarz wrote:
>
>
>
>     I don't think we need to import Mongo type notation here. But
>     there is probably a good case for some functions like:
>
>        json_table_agg(anyrecord) -> json
>
>     which would work like json_agg() but would return an array of
>     arrays instead of an array of objects. The caller would be assumed
>     to know which field is which in the array. That should take care
>     of both the table_to_json and query_to_json suggestions above.
>
>     In the other direction, we could have something like:
>
>         json_populate_recordset_from_table(base anyrecord, fields
>     text[], jsontable json) -> setof record
>
>     where jsontable is an array of arrays of values  and fields is a
>     corresponding array of field names.
>
>     I'm not sure how mainstream any of this is. Maybe an extension
>     would be more appropriate?
>
>
>
>
> Hello.
>
> My personal interest is to send updates to a single json value in the
> server. Which is the best way to make a update to a json value in
> postgres without a full update of the already stored value??  the ->
> operator extract a internal value, but to update the value I don't see
> any operator.
>
> I was not familiar with the extensions, but it looks like the best way
> to start is to create a extension with possible implementations of new
> functions. I will do so.
>
> In my project I considered to use mongo, but in my case the core part
> of the model match perfectly a relational schema. I have some leaf
> concepts that will change frequently, and to avoid migrations I store
> that information in a json value. To make changes in such leaf values
> I would like to have a "context lenses like api" in the server. I will
> start with some toy extension and try to feel if this make sense.
>
>

There is work already being done on providing update operations.

cheers

andrew