Re: XML CLOB Parsing Problems

Hi Tom,

When I pass the values as CLOB to the xml parser via xml-into, I'm
receiving xml parser errors. If I convert the CLOB values to native
varying length strings, the strings include extra characters at the
beginning which also cause parser problems.

When you define a field as SQLTYPE(CLOB) the SQL precompiler converts it into a data structure containing a 4-byte unsigned integer containing the length of the data, and an alphanumeric field containing the actual data.

For example, if I wrote the following code:

D parm1 S SQLTYPE(CLOB:65530)

The SQL precompiler would actually generate code like this (and this is the actual RPG code that gets compiled into a *PGM):

D parm1 DS
D parm1_len 10U 0
D parm1_data 65530A

Now... you say that you are assigning this to an internal RPG varying field in order to pass it to XML-INTO (Which I think is a good idea, BTW). But you say you're getting "extra characters" at the beginning. From that description, I suspect you're doing the following (which is incorrect):

D tempvar s 65530a varying
/free
tempvar = parm1;

Why is that incorrect? Because you're treating the whole data structure as one big string instead of looking at the subfields. So you're going to set the length of the VARYING field to 65534, unconditionally, because that's the total length of the data structure. The first 4 bytes will be the hex value of the length (i.e., your "extra characters") because you're not treating it as the length -- instead, you're treating it as a part of the data in the field.

Instead, I suggest writing your code like this:

tempvar = %subst(parm1_data:1:parm1_len);

This way, you're explicitly telling it that parm1_len contains the length of data you want to extract from parm1. and parm1_data contains the data to be extracted.

I guess the thing to keep in mind when using an SQLTYPE field is that it's not a "real" variable. The SQL precompiler will convert it into something else that's legal RPG code -- you need to be mindful of what it'll be converted into.