What is the meaning of array elements of *type_info variables in SOAP / WSDL auto-generated Apex classes?

Question

Background:

As an example, let's put the calculatorServices class from the Apex SOAP Callouts Trailhead Unit on the table. Considering any of the inner classes, for instance doAdd:

public class doAdd {
    public Double arg0;
    public Double arg1;
    private String[] arg0_type_info = new String[]{'arg0','http://calculator.services/',null,'0','1','false'};
    private String[] arg1_type_info = new String[]{'arg1','http://calculator.services/',null,'0','1','false'};
    private String[] apex_schema_type_info = new String[]{'http://calculator.services/','false','false'};
    private String[] field_order_type_info = new String[]{'arg0','arg1'};
}

There are always 3 types of type_info variables:

• element-specific (arg0_type_info, arg1_type_info etc.)
• apex_schema_type_info
• field_order_type_info

All of these are described by elements of String arrays.

Question:

Does anyone know what's the description/names/meanings of each of these array elements? I couldn't find anything among SF documentation, SF blogs or other SO posts.

What I've got so far:

• first array element in ELEMENT_type_info is basically its name
• second array element in ELEMENT_type_info is either tns or targetNamespace
• first array element in apex_schema_type_info is either tns or targetNamespace
• field_order_type_info array's meaning is obvious

The reason behind my question is that due to WSDL2Apex generator limitations I'm forced to write my own Apex SOAP classes manually (inb4: yes, I saw FuseIT generator, it crashes for my WSDL). I have managed to write some basic (and working!) code already, but I'm not sure if leaving all these null, '0', '1', 'false' values is fine or I should change some of them due to things I'm just not aware of.

Any help appreciated, thanks :)

Answer 1

The details are fairly well covered in What are the parameters for the Salesforce WebServiceCallout.invoke method?

From Jeremy's answer:

If the variable represents another XML element or a text node, then there needs to be a matching _type_info String[] e.g. bar_type_info. The elements of this array are:

1. XML element name
2. Schema
3. XML type
4. minOccurs
5. maxOccurs (set to '-1' for unbounded)
6. isNillable

If in doubt, Salesforce made their version of WSDL2Apex open source, so you can see how it is setting the array elements.

private String typeInfo(Element element) {
    String elemNs =
            element.getRef() == null ? element.getSchema().getTargetNamespace() : element.getRef()
                    .getNamespaceURI();

    StringBuilder sb = new StringBuilder();
    sb.append("new String[]{");
    sb.append("'").append(element.getName()).append("'");
    sb.append(",'").append(elemNs).append("'");
    sb.append(",").append("null"); // Was the element's type, no longer used.
    sb.append(",'").append(element.getMinOccurs()).append("'");
    sb.append(",'").append(element.getMaxOccurs()).append("'");
    sb.append(",'").append(element.isNillable()).append("'");
    sb.append("}");
    return sb.toString();
}