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Might there be a bug in the XQuery function fme:process-features (JSONTemplater)

  • February 16, 2017
  • 5 replies
  • 63 views
V
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Hi !

 

 

When using the JSON Templater, loading sub-templates using the xquery fme:process-features, I get an error when one of my json documents (generated by a previous JSON Templater) contains an ampersand (&) 

Here is the error :

JSONTemplater_Annonce(XMLTemplaterFactory): invalid expression: syntax error, invalid character or entity reference "& ASSO..." in the string literal "CABINET PIERRE SMITH & ASSOCIES".

Could it consider the ampersand to be a reserved character of the xquery language even whitin double-quotes ?

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5 replies

david_r
Celebrity
  • david_rCelebrity
  • February 16, 2017

Maybe someone else can confirm, but I suspect that the ampersand is considered a special character in XQuery, cf. https://en.wikibooks.org/wiki/XQuery/Special_Characters

Try using a StringReplacer to replace the ampersands with either "&" or to "&".

takashi
Celebrity
  • takashiCelebrity
  • February 16, 2017

Yes, in XQuery expressions, the ampersand can only be represented using the entity reference or character reference. See also this link.

W3C Recommendation | XQuery 3.0: An XML Query Language | 2.4.5 URI Literals

This expression causes the error.

{
    "CABINET PIERRE SMITH & ASSOCIES": "foo bar"
}

To avoid the error,

a) escape the ampersand with the predefined entity reference (&),

{
    "CABINET PIERRE SMITH & ASSOCIES": "foo bar"
}

b) or save the string literal as a feature attribute (e.g. called "name") beforehand and use FME predefined XQuery function "fme:get-attribute" to put the value in the expression.

{
    fme:get-attribute("name"): "foo bar"
}

Note: Since the function escapes the ampersand internally when the expression is evaluated, you don't need to replace the ampersand within the "name" attribute value with the entity reference.

Why not inspect features with Visual/Data Preview and Feature/Record Information before writing them into a destination dataset?
V
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  • vchalmel
  • Author
  • February 17, 2017

Yes, in XQuery expressions, the ampersand can only be represented using the entity reference or character reference. See also this link.

W3C Recommendation | XQuery 3.0: An XML Query Language | 2.4.5 URI Literals

This expression causes the error.

{
    "CABINET PIERRE SMITH & ASSOCIES": "foo bar"
}

To avoid the error,

a) escape the ampersand with the predefined entity reference (&),

{
    "CABINET PIERRE SMITH & ASSOCIES": "foo bar"
}

b) or save the string literal as a feature attribute (e.g. called "name") beforehand and use FME predefined XQuery function "fme:get-attribute" to put the value in the expression.

{
    fme:get-attribute("name"): "foo bar"
}

Note: Since the function escapes the ampersand internally when the expression is evaluated, you don't need to replace the ampersand within the "name" attribute value with the entity reference.

Ok ! Thanks for the answer ! If I use "&" do I need to replace it back when loading it (I will use a python caller, load the json in a python dictionnary, then write it in mongodb) ?

 

 

What's bother me though, is that I indeed used fme:get-attribute to create the json structure in a previous JSON Templater, then used the resulting json attribute in the second JSON Templater as a sub-template... (I guess that's why the & is no-longer escaped, the nested json might be passed as a raw string somewhere inbetween)  maybe if I define all the nested sub-templates in the same json templater, the & would be correctly escaped... I will try that.

 

takashi
Celebrity
  • takashiCelebrity
  • February 17, 2017
Ok ! Thanks for the answer ! If I use "&" do I need to replace it back when loading it (I will use a python caller, load the json in a python dictionnary, then write it in mongodb) ?

 

 

What's bother me though, is that I indeed used fme:get-attribute to create the json structure in a previous JSON Templater, then used the resulting json attribute in the second JSON Templater as a sub-template... (I guess that's why the & is no-longer escaped, the nested json might be passed as a raw string somewhere inbetween) maybe if I define all the nested sub-templates in the same json templater, the & would be correctly escaped... I will try that.

 

I don't think the error could occur even if you are using multiple JSONTemplaters in a series, unless an ampersand exists within a string literal in a template expression. Can you post a workspace example which illustrates your problem?

 

Why not inspect features with Visual/Data Preview and Feature/Record Information before writing them into a destination dataset?
V
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  • vchalmel
  • Author
  • February 21, 2017
I don't think the error could occur even if you are using multiple JSONTemplaters in a series, unless an ampersand exists within a string literal in a template expression. Can you post a workspace example which illustrates your problem?

 

Yes ! I will try to create a specific workspace to showcase this

 

 

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