Re: How to store a boolean expression (parse tree) in a model?

Could you simply make the connector field nullable to express that?

Simon

Le mercredi 19 février 2020 12:15:32 UTC-5, test a écrit :

thanks, do you know how i can create custom leaf nodes when using MPTT or treebeard?

My parent nodes should have connector types such as AND/OR but the child should not

On Tuesday, February 18, 2020 at 11:30:40 PM UTC-5, Simon Charette wrote:

I suggest you have a look at the "Trees and Graph" section of the

Django Packages website[0]. I've personally used MPTT and Treebeard

in the past without too much trouble.

You could also a field able to store composite data structures

such as JSONField or even a dedicated PostgreSQL type[1] to efficiently store

such data.

Cheers,

Simon

[0] https://djangopackages.org/grids/g/trees-and-graphs/

[1] https://www.postgresql.org/docs/current/sql-createtype.html

Le mardi 18 février 2020 18:13:39 UTC-5, test a écrit :

Let's say I have:

Calculator #1:

Expression: (True AND False) AND (True OR False)

This expression should be a child of some calculator. 

class Calculator(models.Model):

name = ...

class Expression(models.Model):

parent = models.ForeignKey(Calculator)

boolean = AND or OR

sub_exp1 = models.ForeignKey(Expression)

sub_exp2 = models.ForeignKey(Expression)

When I query all the expressions for the Calculator #1, I should get all the subexpressions.

1 AND 2 5

2 AND 3 4

3 leaf node of True 

4 lead node of False

5 OR 6 7

6 leaf node of True

7 leaf node of False

From this, I can quickly apply my parse tree.

How would I display the base case/leaf nodes in my model? Also, is there a better way?

Thanks, I would really appreciate any help

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