I would like to put a short JSON string in a memory tag but am getting an error: "Error expanding potential parameter reference in tag" due to the { in the JSON initiating parameter substitution. I've tried a few simple escapes such as \{, \\{ and {{, no joy.
How can I turn this off within the tag?
In Ignition 7.9.2, despite the word "error", this is merely a warning that the JSON can't be interpreted as a substitution. This warning can be ignored unless you are attempting parameter substitution.
I spoke with Ignition support, they said there is no way to avoid this warning, but that they may make improvements here to enable substitution in JSON in a future release.
Related
Currently, I'm working on a feature that involves parsing XML that we receive from another product. I decided to run some tests against some actual customer data, and it looks like the other product is allowing input from users that should be considered invalid. Anyways, I still have to try and figure out a way to parse it. We're using javax.xml.parsers.DocumentBuilder and I'm getting an error on input that looks like the following.
<xml>
...
<description>Example:Description:<THIS-IS-PART-OF-DESCRIPTION></description>
...
</xml>
As you can tell, the description has what appears to be an invalid tag inside of it (<THIS-IS-PART-OF-DESCRIPTION>). Now, this description tag is known to be a leaf tag and shouldn't have any nested tags inside of it. Regardless, this is still an issue and yields an exception on DocumentBuilder.parse(...)
I know this is invalid XML, but it's predictably invalid. Any ideas on a way to parse such input?
That "XML" is worse than invalid – it's not well-formed; see Well Formed vs Valid XML.
An informal assessment of the predictability of the transgressions does not help. That textual data is not XML. No conformant XML tools or libraries can help you process it.
Options, most desirable first:
Have the provider fix the problem on their end. Demand well-formed XML. (Technically the phrase well-formed XML is redundant but may be useful for emphasis.)
Use a tolerant markup parser to cleanup the problem ahead of parsing as XML:
Standalone: xmlstarlet has robust recovering and repair capabilities credit: RomanPerekhrest
xmlstarlet fo -o -R -H -D bad.xml 2>/dev/null
Standalone and C/C++: HTML Tidy works with XML too. Taggle is a port of TagSoup to C++.
Python: Beautiful Soup is Python-based. See notes in the Differences between parsers section. See also answers to this question for more
suggestions for dealing with not-well-formed markup in Python,
including especially lxml's recover=True option.
See also this answer for how to use codecs.EncodedFile() to cleanup illegal characters.
Java: TagSoup and JSoup focus on HTML. FilterInputStream can be used for preprocessing cleanup.
.NET:
XmlReaderSettings.CheckCharacters can
be disabled to get past illegal XML character problems.
#jdweng notes that XmlReaderSettings.ConformanceLevel can be set to
ConformanceLevel.Fragment so that XmlReader can read XML Well-Formed Parsed Entities lacking a root element.
#jdweng also reports that XmlReader.ReadToFollowing() can sometimes
be used to work-around XML syntactical issues, but note
rule-breaking warning in #3 below.
Microsoft.Language.Xml.XMLParser is said to be “error-tolerant”.
Go: Set Decoder.Strict to false as shown in this example by #chuckx.
PHP: See DOMDocument::$recover and libxml_use_internal_errors(true). See nice example here.
Ruby: Nokogiri supports “Gentle Well-Formedness”.
R: See htmlTreeParse() for fault-tolerant markup parsing in R.
Perl: See XML::Liberal, a "super liberal XML parser that parses broken XML."
Process the data as text manually using a text editor or
programmatically using character/string functions. Doing this
programmatically can range from tricky to impossible as
what appears to be
predictable often is not -- rule breaking is rarely bound by rules.
For invalid character errors, use regex to remove/replace invalid characters:
PHP: preg_replace('/[^\x{0009}\x{000a}\x{000d}\x{0020}-\x{D7FF}\x{E000}-\x{FFFD}]+/u', ' ', $s);
Ruby: string.tr("^\u{0009}\u{000a}\u{000d}\u{0020}-\u{D7FF}\u{E000}-\u{FFFD}", ' ')
JavaScript: inputStr.replace(/[^\x09\x0A\x0D\x20-\xFF\x85\xA0-\uD7FF\uE000-\uFDCF\uFDE0-\uFFFD]/gm, '')
For ampersands, use regex to replace matches with &: credit: blhsin, demo
&(?!(?:#\d+|#x[0-9a-f]+|\w+);)
Note that the above regular expressions won't take comments or CDATA
sections into account.
A standard XML parser will NEVER accept invalid XML, by design.
Your only option is to pre-process the input to remove the "predictably invalid" content, or wrap it in CDATA, prior to parsing it.
The accepted answer is good advice, and contains very useful links.
I'd like to add that this, and many other cases of not-wellformed and/or DTD-invalid XML can be repaired using SGML, the ISO-standardized superset of HTML and XML. In your case, what works is to declare the bogus THIS-IS-PART-OF-DESCRIPTION element as SGML empty element and then use eg. the osx program (part of the OpenSP/OpenJade SGML package) to convert it to XML. For example, if you supply the following to osx
<!DOCTYPE xml [
<!ELEMENT xml - - ANY>
<!ELEMENT description - - ANY>
<!ELEMENT THIS-IS-PART-OF-DESCRIPTION - - EMPTY>
]>
<xml>
<description>blah blah
<THIS-IS-PART-OF-DESCRIPTION>
</description>
</xml>
it will output well-formed XML for further processing with the XML tools of your choice.
Note, however, that your example snippet has another problem in that element names starting with the letters xml or XML or Xml etc. are reserved in XML, and won't be accepted by conforming XML parsers.
IMO these cases should be solved by using JSoup.
Below is a not-really answer for this specific case, but found this on the web (thanks to inuyasha82 on Coderwall). This code bit did inspire me for another similar problem while dealing with malformed XMLs, so I share it here.
Please do not edit what is below, as it is as it on the original website.
The XML format, requires to be valid a unique root element declared in the document.
So for example a valid xml is:
<root>
<element>...</element>
<element>...</element>
</root>
But if you have a document like:
<element>...</element>
<element>...</element>
<element>...</element>
<element>...</element>
This will be considered a malformed XML, so many xml parsers just throw an Exception complaining about no root element. Etc.
In this example there is a solution on how to solve that problem and succesfully parse the malformed xml above.
Basically what we will do is to add programmatically a root element.
So first of all you have to open the resource that contains your "malformed" xml (i. e. a file):
File file = new File(pathtofile);
Then open a FileInputStream:
FileInputStream fis = new FileInputStream(file);
If we try to parse this stream with any XML library at that point we will raise the malformed document Exception.
Now we create a list of InputStream objects with three lements:
A ByteIputStream element that contains the string: <root>
Our FileInputStream
A ByteInputStream with the string: </root>
So the code is:
List<InputStream> streams =
Arrays.asList(
new ByteArrayInputStream("<root>".getBytes()),
fis,
new ByteArrayInputStream("</root>".getBytes()));
Now using a SequenceInputStream, we create a container for the List created above:
InputStream cntr =
new SequenceInputStream(Collections.enumeration(str));
Now we can use any XML Parser library, on the cntr, and it will be parsed without any problem. (Checked with Stax library);
result <- z$findElement(using = 'xpath',"//*[contains(text(),'the deal” of hosting major sporting')]")
In above command the reference String have special character the deal” so ,R gave the Error as
Error: Summary: NoSuchElement
Detail: An element could not be located on the page using the given search parameters.
class: org.openqa.selenium.NoSuchElementException
but the reference element found in the particular URL.
I think the issue is with your syntax of 'contains' and the use of double quotes.
Check here below the correct syntax:
[text()[contains(.,'the deal of hosting major sporting')]]
also the error you are getting means that the element wasn't present at the time of checking. This can occur for a number of reasons.Two of the most common are: 1) you checked too early (i.e. a wait should be introduced instead of a delay).
wait.until(ExpectedConditions.elementToBeClickable(By.id<locator>));
2) Your xpath is wrong (most likely). Noticed you are using //* which means any node so as far as we know, you could be pointing to multiple elements. If you want a more specific xpath answer please post a screenshot with the html code of element you are trying to locate. But I'll take an educated guess on the below:
(your way improved without the ")
findElement(using = 'xpath',"//*[contains(text(),'the deal of hosting major sporting')]");
and if that does not work, go for this:
findElement(using = 'xpath',"//*[text()[contains(.,'the deal of hosting major sporting')]]");
Best of luck!
I can think of workarounds on how to get this working however I'm interested in finding out if there's a solution to this specific problem.
I've got a go program which requires a json string arguement:
go run main.go "{ \"field\" : \"value\" }"
No problems so far. However, am I able to run from the command line if one of the json values is another json string?
go run main.go "{ \"json-string\" : \"{\"nestedfield\" : \"nestedvalue\"}\" }"
It would seem that adding escape characters incorrectly matches up the opening and closing quotes. Am I minuderstanding how this is done or is it (and this is the side I'm coming down on) simply not possible?
To reiterate, this is a question that has piqued my curiosity - I'm aware of alternative approaches - I'm hoping for input related to this specific problem.
Why don't you just put your json config to the file and provide config file name to your application using flag package
Based on the feedback from wiredeye I went down the argument route instead. I've modified the program to run on:
go run main.go field:value field2:value json-string:"{\"nestedfield\":nestedvalue}"
I can then iterate over the os.Args and get the nested json within my program. I'm not using flags directly as I don't know the amount of inputs into the program which would have required me to use duplicate flags (not supported) or parse the flag to a collection (doesn't seem to be supported).
Thanks wiredeye
I want to make an XML document from an HTML one so I can use the XML parsing tools. My problem is that my HTML is not guaranteed to be XHTML nor valid. How can I bypass the exceptions? In this string <p> is not terminated, nor is <br> nor <meta>.
var poorHtml:String = "<html><meta content=\"stuff\" name=\"description\"><p>Hello<br></html>";
var html:XML = new XML(poorHtml);
TypeError: Error #1085: The element type "meta" must be terminated by the matching end-tag "</meta>".
I did some searching and couldn't come up with anything except this doesn't really seem possible, the major issue is how should it correct when the format is not valid.
In the case of browsers, every browser does this based upon it's own rules of what should happen in the case that the closing tag isn't found (put it in wherever it would cause the code to produce a valid XML and subsequently DOM tree, or self terminate the tag, or remove the tag, or for the case that a closing tag was found with no opening how should this be handled, what about unclosed attributes etc.).
Unfortunately I don't know of anything in the specification that explains what should be done in this case, with XHTML just like how flex treats it these are fatal errors and result in no functionality rather than how HTML4 treated it with the quirky and transitional DTD options.
To avoid the error or give better error messaging you can use this:
var poorHtml:String = "<html><meta content=\"stuff\" name=\"description\"><p>Hello<br></html>";
try
{
var html:XML = new XML(poorHtml);
}
catch(e:TypeError)
{
trace("error caught")
}
but it's likely you'll be best off using some sort of server side script to validate the XML or correct the XML before passing it over to the client.
There is probably an implementation of HTML Tidy in just about any language you might happen to be working with. This looks promising for your sitation: http://code.google.com/p/as3htmltidylib/
If you don't want to drag in a whole library (I wouldn't), you could just write your own XML parser that handles errors in whatever way suits you (I'd suggest auto-closing tags until the document makes sense again, ignoring end tags with no start tags, maybe un-closing certain special tags such as "body" and "html"). This has the added advantage that you can optimize it for whatever jobs you need it for, i.e. by storing a list of all elements with the attribute "href" as you come to them.
You could try to pass your HTML through HTML Tidy on the server before loading it. I believe that HTML Tidy does a good job at cleaning up broken HTML.
I need to allow the user to submit queries as follows;
/search/"my search string"
but it's failing because of request validation, as outlined in the following 2 questions:
How to include quote characters as a route parameter? Getting "Illegal characters in path" message
How to modify request validation?
I'm currently trying to figure out how to disable request validation for the quote character, but i'd like to know the risks before I actually put the site live with this disabled? I will not disable the request validation unless I can only disable it for the quote character, so I do intend to disallow every other character that's currently not allowed.
According to the URI generic syntax specification (RFC 2396), the double-quote character is explicitly excluded and must be escaped (i.e. %22). See section 2.4.3. The reason given in the spec:
The angle-bracket "<" and ">" and double-quote (") characters are excluded because they are often used as the delimiters around URI in text documents and protocol fields.
You can see easily why this is the case -- imagine trying to create a link in HTML to your URL:
<a href="http://somesite/search/"my search string""/>
That would fail HTML parsing (and also breaks SO's syntax highlighting). You also would have trouble doing basic things with the URL like emailing it to someone (the email client wouldn't parse the URL correctly), posting it on a message board, sending it in an instant message, etc.
For what it's worth, spaces are also explicitly excluded (same section of the RFC explains why).