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

[test]

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

[Simon Charette]

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

[test]

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

[Simon Charette]

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

Simon