XML empty slots in array returned by getChildren(). What am I missing?

Programming Questions

v.k.

XML empty slots in array returned by getChildren(). What am I missing?

in Programming Questions • 3 months ago

Hi first time dealing with XML, already in doubt...

With this simple XML doc:

<?xml version='1.0' encoding='UTF-8'?>

</proposicao>

</proposicoes>

(I edited that from a large XML for testing)

Using this code (basically one of the XML examples):

XML xml;
XML[] props;
void setup() {
xml = loadXML("proj2013solo.xml");
props = xml.getChildren();
println (props);
}

I got his output:

[0]

[1] <proposicao><id>584676</id><nome>PL 5931/2013</nome></proposicao>

[2]

Why those empty entries in the array? Is this normal? How should I deal with them? Just ignore? It's supposed to a be a HUGE xml file, thousands of empty lines... Thoughts?

Processing 2.0.1

Replies(7)

v.k.

Re: XML empty slots in array returned by getChildren(). What am I missing?

3 months ago

so far I'm doing:

XML xml;
ArrayList<XML> props = new ArrayList<XML>();
void setup() {
xml = loadXML("proj2013part.xml");
XML[] temp = xml.getChildren();
for (int i = 0; i < temp.length; i++){
if(temp[i].hasChildren())
props.add(temp[i]);
}
}

Is it? :)

PhiLho

Re: XML empty slots in array returned by getChildren(). What am I missing?

3 months ago

https://github.com/processing/processing/issues/1164?source=cc
https://github.com/processing/processing/issues/1581?source=cc
https://github.com/processing/processing/issues/1796?source=cc
and lot of others...

Time for a Technical FAQ, I think...

v.k.

Re: XML empty slots in array returned by getChildren(). What am I missing?

3 months ago

Thanks PhiLho.

So if I know the child name I can use xml.getChildren("name"); this will work. But if I don't... well, fortunately i do in this case :)

PhiLho

Re: XML empty slots in array returned by getChildren(). What am I missing?

3 months ago

You rarely parse an XML of unknown content... If you do, how do you know what you are looking for? If you are only interested in text nodes, for example, you can then iterate on them and eliminate all those made only of whitespace (including \r and \n).

v.k.

Re: XML empty slots in array returned by getChildren(). What am I missing?

3 months ago

That makes sense :) Thanks.

Once we are here... Let's check if my approach is a good one, if you don't mind...

My XML looks like:

<prop>

<field2>a String</field2>

<field3>has some children</field3>

<field3.1>an int</field3.1>

<field3.2>a String</field3.2>

</prop>

So I made an object Prop to receive a prop, and another object Field3 with it's own fields goes like:

class Prop{
int anInt;
String aString;
Field3 aField3;
}
class Field3{
int f3_anInt;
String f3_aString;
}

Now, is this a good way to go? Should Field3 be inside Prop as an inner class?

Thanks for any advice.

PhiLho

Re: XML empty slots in array returned by getChildren(). What am I missing?

3 months ago

There are two problems with your dummy example:
- It is dummy! (not representative of a real problem)
- It is incorrect:
Beside the fact that field3.1 isn't a valid tag name, which isn't important here, it is not inside the field3 tag, it is beside it, despite what the indentation might suggest...

More seriously, actually, you can use whatever data structure fits your needs: you just have to fill in the fields of the class with the values you find in the XML.
You don't necessarily need to reflect the (supposed) nesting of field3.1 and field3.2 inside field3. Your structure can be just flat, unless your need must show this hierarchy.
Inner class or not depends also on the real use case. Usually, you do an inner class either to hide it from the external world (encapsulation) or to show there is a strong coupling between the classes, the inner cannot exist without the external one.

v.k.

Re: XML empty slots in array returned by getChildren(). What am I missing?

3 months ago

Thanks PhiLho, again that makes sense. In fact I'm not sure yet how those things should work. This API is not well documented, and have some flaws that I found already. Maybe they don't really want us to use it... It is the API of Brasil's congress... Anyway I'll keep exploring it, and coming back here when needed.