[Info] Allowable Classes for "set_attribute"

kwalkerman

Under the Ruby API for "set_attribute" we get:

Arguments:
dict_name: The name of an attribute dictionary.
key: An attribute key.
value: The value for the attribute.

Returns:
value: the newly set value if successful

but, it doesn't tell you what type of values are allowable. Here is my short list:

allowed:

String
Fixnum
Float
Array -- For arrays, every element in the array needs to be one of the allowed types on this list.
TrueClass
FalseClass
Length
Geom::Point3d (tested under SU8 M1)
Geom::Vector3d (tested under SU8 M1)

not allowed:

Entity
Hash -- this can be stored following Dan's guidelines below.

Be careful with hash, because if you have an array, and one of the array values is a hash, it will return the array, but instead of returning the hash, it will return nil.

Additions? Corrections? Comments?

--
Karen

thomthom

Yea - wish the API docs would spesify this.
CAn't remember if the TrueClass and FalseClass worked..

Dan Rathbun

@kwalkerman said:

not allowed:

Hash -- (kind of strange, as array is allowed)

A JSON string is a hash definition, almost verbatim Ruby, with quotes.
The diference is that the => are replaced with colon. JSON (JavaScript Object Notation,) strings are handy because you can pass them to webdialogs. They can contain nested Arrays, and I think even nested JSONs.

But if your data is going to stay within Ruby, and you want "record type" data fields with keynames and values, then use a hash.

It's VERY easy to store a hash in an attribute.

(Get ready to smack your forehead.)


my_hash = {'Name'=>'Dan','Age'=>49,'Stature'=>5.5,
           'FavFoods'=>['Mac and Cheese','SpiceCake','Coffee']}

some_entity.set_attribute( "dict_name", "hash_att", my_hash.inspect )

Jim

When you say Arrays are allowed, what about the types of the elements?

thomthom

@dan rathbun said:

@kwalkerman said:

It's VERY easy to store a hash in an attribute.

How do you turn it back into an hash when you read it?

Jim

Unless your Hash string includes quotes, in which case you need to escape those first.

Dan Rathbun

@jim said:

Unless your Hash string includes quotes, in which case you need to escape those first.

NOPE.. Ruby does it for you.

` hashStr = %( {"Stature"=>5.5, "Name"=>"Dan", "FavFoods"=>["Mac and Cheese", "SpiceCake", "Coffee"], "Age"=>49})

hashStr.inspect

" {"Stature"=>5.5, "Name"=>"Dan", "FavFoods"=>["Mac and Cheese", "SpiceCake", "Coffee"], "Age"=>49}"

my_hash = eval(hashStr)

{"Stature"=>5.5, "Name"=>"Dan", "FavFoods"=>["Mac and Cheese", "SpiceCake", "Coffee"], "Age"=>49}

my_hash.class

Hash`

Jim

Huh, I thought I had problems with that in the past.

Dan Rathbun

@jim said:

Huh, I thought I had problems with that in the past.

Could be.

Might have been using Ruby 1.8.0* Might have been conflicts between PC (1.8.0) and Mac (1.8.5)* I imagine you could confuse Ruby with poor use of delimiters, or maybe embedded newlines?
I would always recommend using .inspect to build the string, as it:
Correctly knows how to iterate the hash, and any nested structures inside it, like nested arrays, nested hashes, etc.* For objects that it does not know how to 'convert' it will make an 'info string': "#Sketchup::Face:0x3F56D20A" (or similar)* Uses the same delimiters (double quotes,) for all strings and hash keys (which allows the use of a single quote for possesion apostrophe. ie: "Dan's idea!"

Dan Rathbun

@kwalkerman said:

Be careful with hash, because if you have an array, and one of the array values is a hash, it will return the array, but instead of returning the hash, it will return nil.

See the post directly above.

The "tip" on using .inspect (to build the attribute strings,) for hashes, goes also for arrays.
The .inspect method will convert hashes nested inside arrays, and arrays nested inside hashes, etc. Multiple levels deep as well.

kwalkerman

Dan,

Very nice. I will definitely use this. Too bad it's not embedded in SU though.

Jim - I have found that any sub-components of arrays also need to be one of the allowable classes.

Thom - trueclass and falseclass also work. I'm updating the first post accordingly.

--
Karen

zitoun

VERY useful thread, thanks !
Please make it kind of sticky: I've been chasing an uncatchable bug for hours, ignoring this information... Others might like to know this in the future!

Dan Rathbun

To recover a hash-string from an attribute, you eval() it into a reference.


hashStr = some_entity.get_attribute( "dict_name", "hash_att" )

my_hash = eval(hashStr)

thomthom

Length classes also seem to be stored and recovered properly. I'd thought that maybe it got read back as Float, but in my tests I seem to get Length - anyone confirm?

thomthom

@kwalkerman said:

Array -- good to store by doing "array.inspect" first, see Dan's comments below

Only if the array contains hashes. If the array only use the other allowable types there is no need. Might be less overhead since it's not parsing between strings.

thomthom

Geom::Point3d also seems to be possible to store:

` pt1=Geom::Point3d.new(1,2,3)
Point3d(1, 2, 3)
pt2=Geom::Point3d.new(4,5,6)
Point3d(4, 5, 6)
pt3=Geom::Point3d.new(7,8,9)
Point3d(7, 8, 9)

pt_array = [ pt1, pt2, pt3 ]
[Point3d(1, 2, 3), Point3d(4, 5, 6), Point3d(7, 8, 9)]

model.set_attribute('test', 'bar', pt_array )
[Point3d(1, 2, 3), Point3d(4, 5, 6), Point3d(7, 8, 9)]

model.get_attribute('test', 'bar' )
[Point3d(1, 2, 3), Point3d(4, 5, 6), Point3d(7, 8, 9)]`

I even saved the model and reopened it just to make sure it worked across sessions.

TIG

Although storing/reading-back a 'point3d' or a 'vector3d' as an array [.to_a] would be 'safer' ?
Presumably a 'transformation' is not storeable unless it's first made into an array ?

thomthom

@tig said:

Although storing/reading-back a 'point3d' or a 'vector3d' as an array [.to_a] would be 'safer' ?

I was storing points as arrays - because I just assumed point3d's would not work. But they appear to do so. In which case I'd prefer to do so unless there is any known issues.