Feature: tree data integrity

[goosechaser]

Hi,

Thanks for the package. One thing that I find it lacks is the data integrity check like in CakePHP's Tree, for example: http://book.cakephp.org/2.0/en/core-libraries/behaviors/tree.html#data-integrity

If you ever have time, it'd be great if this was introduced.

[lazychaser]

The thing is that you can't set parent_id explicitly. When you change it, the node is appended to that parent. That is why you need a root node. To prevent any data curruption use transactions.

[goosechaser]

Transactions help to an extent. Here's my real use case: I dump a tree into JSON on the server, let clients manipulate data in browser, and then loop through object received from clients on the server by updating the DB's _lft and _rght fields (my front-end plugin adjusts these fields when data is changed by a client). However, IF the client decides to tamper with data (say, change the JSON object that's sent to the server by making all _lft fields = 0), then I have no way of verifying data integrity after doing the update. My current workaround: perform change on the server as soon as it's done on the client side. 100 changes = 100 server requests. I would prefer 100 changes and 1 server request.

[lazychaser]

You can update a structure in other manner. In the browser you just store structure manipulations like "put this node into this parent", "insert this node before this node", etc and "playback" this actions on server. Other data is updated as usual.

[goosechaser]

It's not temper-proof since the client can still mess with the manipulations data that's sent to the server.

[lazychaser]

He can. But he'll need to pass this data through high-level layer which is secure. I.e. you'll have a command like ['before', 12, 13] which means: take a node with an id of 12 and insert it before node with an id of 13. If either one isn't exists you just throw an exception, transaction is rolled back, everyone's happy.

[goosechaser]

Thanks, I guess I'll resort to that method.