JSONField() ordering and removing latest

[wagner]

Hello together,

i have the following problem. I need to save different versions of an article in a json object:

{

"1580388458.2877874": {

"title": "Erster Artikel", 

"text_block_with_image": [{"text": "Super Text der einen weiterhilft", "image": "http://test.de/test.jpg"}]

}, 

"1580388556.6462297": {

"title": "Erster Artikel angepasst", 

"text_block_with_image": [{"text": "Super neuer neuer Text der einen weiterhilft", "image": "http://test.de/test.jpg"}]

}

}

I save this information in a JSONField().

The numbers here are the current time in seconds. 

I want to do an article template where i show the latest version of the article (by current time seconds).

How can i filter after the latest version?

Articles.objects.filter( ?? )

My second problem:

How can i delete the oldest version (key), when i add a new entry?

Thank you!

[Jody Fitzpatrick]

I would change the model a bit, instead of having the timestamp as the key, i would set it in the dict.

I believe that would be cleaner and would allow you to do a bit more of what you are going for.

[Andrew C.]

Usually, something that has multiple versions could be in an autoincrement field as the primary key. Then, in a JSONB field with GIN index (since you’re using PostgreSQL), you would have a dict of each version, like this:

{

“1”: { # beginning of article 1

“versions”: {

“1”: {

“title”: “Blah1”,

“timestamp”: 172903740.0002782,

“image”: “http:test.de/test.jpg”,

“alt”: “Super text”

}, # end of version 1

“2”: {

“title”: “Blah1”,

“timestamp”: 1729375394.0002782,

“image”: “http:test.de/test.jpg”,

“alt”: “Super text blah”

}, # end of version 2

“3”: {

“title”: “Blah2”,

“timestamp”: 17290826300.0002782,

“image”: “http:test.de/test.jpg”,

“alt”: “Super text blah”

} # end of version 3 

} # end of versions attribute/column

}, # end of article 1

“2”: {

“versions”: {

“1”: {

“title”: “Blah1”,

“timestamp”: 172903740.0002782,

“image”: “http:test.de/test.jpg”,

“alt”: “Super text”

}, # end of version 1

“2”: {

“title”: “Blah1”,

“timestamp”: 172903740.0002782,

“image”: “http:test.de/test.jpg”,

“alt”: “Super text blah”

} # end of version 2

} # end of article 2

} # end of queryset

So your primary key is a BigAutoField and your “versions” attribute/column is a JSONField. IF YOU ARE FILTERING BASED ON ARTICLE TITLE, make sure you put a GIN Index on that JSONField.

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