Writing Translator Code

Below we will describe how thedetect*anddo*188BET靠谱吗functions of Zoterotranslatorscan and should be coded.If you are unfamiliar with JavaScript, make sure to check out aJavaScript tutorialto get familiar with the syntax.In addition to the information on this page, it can often be very informative to look at existing translators to see how things are done.Aparticularly helpful guide188BET靠谱吗with up-to-date recommendation on best coding practices is provided by the Wikimedia Foundation, whose tool Citoid uses Zotero translators.

While translators can be written with any text editor, the built-inTranslator Editorcan make writing them much easier, as it provides the option to test and troubleshoot translators relatively quickly.

New web translators should use the Translator Editor's web translator template as a starting point.The template can be inserted in the Code tab: click the green plus dropdown and choose "Add web translator template".

Web Translators

detectWeb

detectWebis run to determine whether item metadata can indeed be retrieved from the webpage.The return value of this function should be the detected item type (e.g."journalArticle", see the188BET靠谱吗overview of Zotero item types), or, if multiple items are found, "multiple".If no item(s) can be detected on the current page, return false.

detectWebreceives two arguments: the webpage document object andURL(typically nameddocandurl).In some cases, theURLprovides all the information needed to determine whether item metadata is available, allowing for a simpledetectWebfunction, e.g.(example fromCell Press.js):

functiondetectWeb(doc,url){if(url.includes("search/results")){return"multiple";}elseif(url.includes("content/article")){return"journalArticle";}returnfalse;}

doWeb

doWebis run when a user, wishing to save one or more items, activates the selected translator.It can be seen as the entry point of the translation process.

The signature ofdoWebshould be

doWeb(doc,url)

Heredoc188BET靠谱吗refers to the DOM object of the web page that the user wants to save as a Zotero item, andurlis the page'sURLas a string.

In this section, we will describe the common tasks in the translation workflow started bydoWeb().

Saving Single Items

Scraping for metadata

188BET靠谱吗"Scraping" refers to the act of collecting information that can be used to populate Zotero item fields from the web page.Such information typically include the title, creators, permanentURL, and source of the work being saved (for example, the title/volume/pages of a journal).

Having identified what information to look for, you need to know where to look.The best way to do this is to use the web inspections tools that come with the browser (Firefox,Chromium-based, andWebkit/Safari).They are indispensable for locating the DOM node /HTMLelement – by visual inspection, searching, or browsing the DOM tree.

To actually retrieve information from the nodes in your translator code, you should be familiar with the use ofselectors, in the way they are used with the JavaScriptAPIfunctionquerySelectorAll().

Most often, you will do the scraping using the helper functionstext()andattr(), for retrieving text content and attribute value, respectively.In fact, these two actions are performed so often, thattext()andattr()are available to the translator script as top-level functions.

functiontext(parentNode,selector[,index])functionattr(parentNode,selector,attributeName[,index])
  • text()finds the descendant of parentNode(which can also be a document) that matches selector, and returns the text content (i.e.the value of the textContentproperty) of the selected node, with leading and trailing whitespace trimmed.If the selector doesn't match, the empty string is returned.
  • attr()similarly uses the selector to locate a descendant node.However, it returns the value of the HTMLattribute attributeNameon that element.If the selector doesn't match, or if the there's no specified attribute on that element, the empty string is returned.

Optionally, a numberindex(zero-based) can be used to select a specific node when the selector matches multiple nodes.If the index is out of range, the return value of both function will be the empty string.

Another less-used helper functioninnerText()has the same signature astext(), but it differs from the latter by returning the selected node'sinnerTextvalue, which is affected by how the node's content would have been rendered.

In addition, you can always use theAPIfunctionsquerySelectorandquerySelectorAlldirectly, but the helper functions should be preferred when they are adequate for the job.

In some older translator code, you are likely to encounter node-selection expressed by XPath.Although XPath has its uses, for the most common types of scraping the selector-based functions should be preferred because of the simpler syntax of selectors.

Metadata

The first step towards saving an item is to create an item object of the desireditem type(examples from "NCBI PubMed.js"):

varnewItem=new188BET靠谱吗Zotero.Item("journalArticle");

Metadata can then be stored in the properties of the object.Of the different fields available for the chosen item type (see theField Index), only the title is required.E.g.:

vartitle=article.ArticleTitle.text().toString();newItem.title=title;varPMID=citation.PMID.text().toString();newItem.url="http://www.ncbi.nlm.nih.gov/pubmed/"+PMID;

After all metadata has been stored in the item object, the item can be saved:

newItem.complete();

This process can be repeated (e.g.using a loop) to save multiple items.

Attachments

Attachments may be saved alongside item metadata via the item object'sattachmentsproperty.Common attachment types are full-text PDFs, links and snapshots.An example from "Pubmed Central.js":

varlinkURL="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC"+ids[i]+"/";newItem.attachments=[{url:linkURL,title:"PubMed Central Link",mimeType:"text/html",snapshot:false}];varpdfURL="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC"+ids[i]+"/pdf/"+pdfFileName;newItem.attachments.push({title:"Full Text PDF",mimeType:"application/pdf",url:pdfURL});

An attachment can only be saved if the source is indicated.The source is often aURL(set on theurlproperty), but can also be a file path (set onpath) or a document object (set ondocument).Other properties that can be set aremimeType("text/html" for webpages, "application/pdf" for PDFs),title, andsnapshot(if the latter is set tofalse, an attached webpage is always saved as a link).

In the very common case of saving the current page as an attachment, setdocument188BET靠谱吗to the current document, so that Zotero doesn't have to make an additional request:

newItem.attachments.push({title:"Snapshot",document:doc});

Whendocumentis set, the MIME type will be set automatically.

188BET靠谱吗Zotero will automatically use proxied versions of attachment URLs returned from translators when the original page was proxied, which allows translators to construct and return attachment URLs without needing to know whether proxying is in use.However, some sites expect unproxied PDF URLs at all times, causing PDF downloads to potentially fail if requested via a proxy.If a PDFURLis extracted directly from the page, it's already a functioning link that's proxied or not as appropriate, and a translator should includeproxy: falsein the attachment metadata to indicate that further proxying should not be performed:

item.attachments.push({url:realPDF,title:"EBSCO Full Text",mimeType:"application/pdf",proxy:false});

Notes

Notes are saved similarly to attachments.The content of the note, which should consist of a string, should be stored in thenoteproperty of the item'snotesproperty.E.g.:

let bbCite="Bluebook citation: "+bbCite+".";newItem.notes.push({note:bbCite});

When saving more than one item from a single source, relationships can be established between the items being saved.These relationships are established using two properties of the item object:seeAlsoanditemID.To establish a relationship, setitemIDto some unique value on one or more of the item objects, and assign an array of the IDs of related items to theseeAlsoproperty of another item object.

Note:TheitemID188BET靠谱吗used here is completely ad hoc– it has nothing to do with the internal ID that Zotero assigns items once they are saved.188BET靠谱吗Also, it is not possible to establish a relationship to an item previously saved to Zotero, since non-export translators have no access to the local library.

When the item objects are saved viaitem.complete(), the relationships will be established.The following code illustrates a simple seeAlso relationship:

functiondoWeb(doc,url){188BET靠谱吗Zotero.debug("Simple example of setting seeAlso relations");let items=[];// Real data acquisition would happen herevartitles=["Book A","Book B"];for(let title of titles){let item=new188BET靠谱吗Zotero.Item("book");item.title=title;items.push(item);}// Assign a bogus itemID to each item in the setfor(let i=0;i<items.length;i++){items[i].itemID=""+i;}// Set bogus itemIDs in each item's seeAlso// field (skipping the item's own ID)for(let i=0;i<items.length;i++){for(let j=0;j<items.length;j++){if(i===j){continue;}items[i].seeAlso.push(""+j);}}// Save the itemsfor(let item of items){item.complete();}};

Saving Multiple Items

Some webpages, such as those showing search results or the index of a journal issue, list multiple items.188BET靠谱吗For these pages, web translators can be written to a) allow the user to select one or more items and b) batch save the selected items to the user's Zotero library.

Item Selection

To present the user with a selection window that shows all the items that have been found on the webpage, a JavaScript object should be created.Then, for each item, an item ID and label should be stored in the object as a property/value pair.The item ID is used internally by the translator, and can be aURL, DOI, or any other identifier, whereas the label is shown to the user (this will usually be the item's title).Passing the object to the188BET靠谱吗Zotero.selectItemsfunction will trigger the selection window, and the function passed as the second argument will receive an object with the selected items (orfalseif the user canceled the operation), as in this example:

188BET靠谱吗Zotero.selectItems(getSearchResults(doc,false),function(items){if(items)ZU.processDocuments(Object.keys(items),scrape);});

Here,188BET靠谱吗Zotero.selectItems(..)is called with an anonymous function as the callback.As in many translators, the selected items are simply loaded into an array and passed off to a processing function that makes requests for each of them.

Batch Saving

You will often need to make additional requests to fetch all the metadata needed, either to make multiple items, or to get additional information on a single item.The most common and reliable way to make such requests is with the utility functions188BET靠谱吗Zotero.Utilities.doGet,188BET靠谱吗Zotero.Utilities.doPost, and188BET靠谱吗Zotero.Utilities.processDocuments.New and updated translators should use the new async HTTP request methods.Documentation is forthcoming, but look forawait requestin existing translators for examples.

Import Translators

To read in the input text, call188BET靠谱吗Zotero.read():

varline;while((line=188BET靠谱吗Zotero.read())!==false)){// Do something}

If given an integer argument, the function will provide up to the specific number of bytes.188BET靠谱吗Zotero.read()returns false when it reaches the end of the file.

IfdataModeinthe translator metadatais set tordf/xmlorxml/dom, the input will be parsed accordingly, and the data will be made available through188BET靠谱吗Zotero.RDFand188BET靠谱吗Zotero.getXML(), respectively.Documentation for these input modes is not available, but consult the RDF translators ("RDF.js", "Bibliontology RDF.js", "Embedded RDF.js") and XML-based translators ("MODS.js", "CTX.js") to see how these modes can be used.

Creating Collections

To create collections, make a collection object and append objects to itschildrenattribute.188BET靠谱吗Just like ordinary Zotero items, you must callcollection.complete()to save a collection– otherwise it will be silently discarded.

varitem=new188BET靠谱吗Zotero.Item("book");item.itemID="my-item-id";// any string or numberitem.complete();varcollection=new188BET靠谱吗Zotero.Collection();collection.name="Test Collection";collection.type="collection";collection.children=[{type:"item",id:"my-item-id"}];collection.complete();

The children of a collection can include other collections.In this case,collection.complete()should be called only on the top-level collection.

Export Translators

Export translators use188BET靠谱吗Zotero.nextItem()and optionally188BET靠谱吗Zotero.nextCollection()to iterate through the items selected for export, and generally write their output using188BET靠谱吗Zotero.write(text).A minimal translator might be:

functiondoExport(){varitem;while(item=188BET靠谱吗Zotero.nextItem()){188BET靠谱吗Zotero.write(item.title);}}

As with import translators, it is also possible to produce XML and RDF/XML using188BET靠谱吗Zotero.RDF.See for example188BET靠谱吗Zotero RDFwhich is a RDF export translator, which also deals with collections.

Exporting Collections

IfconfigOptionsinthe translator metadatahas thegetCollectionsattribute set totrue, the188BET靠谱吗Zotero.nextCollection()call will be available.It provides collection objects like those created on import.

while((collection=188BET靠谱吗Zotero.nextCollection())){// Do something}

The function188BET靠谱吗Zotero.nextCollection()returns a collection object:

{id:"ABCD1234",// Eight-character hexadecimal keychildren:[item,item,..,item],188BET靠谱吗// Array of Zotero item objectsname:"Test Collection"}

The collection ID here is the same thing as the collection key used inAPI calls.

Search Translators

ThedetectSearchanddoSearchfunctions of search translators are passed item objects.On any given inputdetectSearchshould returntrueorfalse, as in "COinS.js":

functiondetectSearch(item){if(item.itemType==="journalArticle"||item.DOI){returntrue;}returnfalse;}

doSearchshould augment the provided item with additional information and callitem.complete()when done.Since search translators are never called directly, but only by other translators or by theAdd Item by Identifier(magic wand) function, it is common for the information to be further processed an''itemDone'' handlerspecified in the calling translator.

Further Reference

Utility Functions

188BET靠谱吗Zotero provides severalutility functionsfor translators to use.Some of them are used for asynchronous and synchronous HTTP requests!those arediscussed above.188BET靠谱吗In addition to those HTTP functions and the many standard functions provided by JavaScript, Zotero provides:

188BET靠谱吗Zotero.Utilitiescan optionally be replaced with the shorthandZUand188BET靠谱吗withZ, as inZU.capitalizeTitle(..)andZ.debug(..).

Function and Object Index

See also theFunction and Object Index, which lists (without documentation), all the functions and objects are accessible to translators.

Calling other translators

Web translators can call other translators to parse metadata provided in a standard format with the help of existing import translators, or to augment incomplete data with the help of search translators.There are several ways of invoking other translators.

Calling a translator by UUID

This is the most common way to use another translator– simply specify the translator type and the UUID of the desired translator.In this case, the RIS translator is being called.

vartranslator=188BET靠谱吗Zotero.loadTranslator("import");translator.setTranslator("32d59d2d-b65a-4da4-b0a3-bdd3cfb979e7");translator.setString(text);translator.translate();

Calling a translator using ''getTranslators''

This code, based on the "COinS.js" code, callsgetTranslators()to identify which search translators can make a complete item out of the basic template information already present.Note thattranslate()is called from within the event handler.Analogous logic could be used to get the right import translator for incoming metadata in an unknown format.

varsearch=188BET靠谱吗Zotero.loadTranslator("search");search.setHandler("translators",function(obj,translators){search.setTranslator(translators);search.translate();});search.setSearch(item);// look for translators for given itemsearch.getTranslators();

Using ''getTranslatorObject''

The MARC translator is one of several translators that provide an interface to their internal logic by exposing several objects, listed in theirexportsarray.Here, it provides an object that encapsulates the MARC logic.The translator can also take input specified viasetStringthat can take binary MARC, but this provides a way for library catalog translators to feed human-readable MARC into the translator.

// Load MARCvartranslator=188BET靠谱吗Zotero.loadTranslator("import");translator.setTranslator("a6ee60df-1ddc-4aae-bb25-45e0537be973");translator.getTranslatorObject(function(obj){varrecord=obj.record();record.leader="leader goes here";record.addField(code,indicator,content);varitem=new188BET靠谱吗Zotero.Item();record.translate(item);item.libraryCatalog=188BET靠谱吗"Zotero.org Library Catalog";item.complete();});

Method overview

  • 188BET靠谱吗Zotero.loadTranslator(type)
    Type should be one of importor search.Returns an object with the methods below.
  • translator.setSearch(item)
    For search translators.Sets the skeleton item object the translator will use for its search.
  • translator.setString(string)
    For import translators.Sets the string that the translator will import from.
  • translator.setDocument(document)
    For web translators.Sets the document that the translator will use.
  • translator.setTranslator(translator)
    Takes translator object (returned by getTranslators(..), or the UUID of a translator.
  • translator.setHandler(event, callback)
    Valid events are itemDone, done, translators, error.The itemDonehandler is called on each invocation of item.complete()in the translator, and the specified callback is passed two arguments: the translator object and the item in question. Note:The itemDonecallback is responsible for calling item.complete()on the item it receives, otherwise the item will not be saved to the database.
  • translator.getTranslators()
    Send a translatorsevent to the registered handler (use setHandler, above).The handler will be called with, as its second argument, an array of those translators that return a non-false value for detectImport, detectSearchor detectWebwhen passed the input given with setString, setSearch, etc.
  • translator.getTranslatorObject(callback)
    The callback is passed an object that has the variables and functions defined in the translator as attributes and methods.In connectors, only the exportsobject, if present in the translator, will be passed to the callback.If an exportsobject is present, other functions and variables in the translator will not be passed to the callback, even when running in Firefox.
    This is typically used when calling import translators that define utility functions, like the MARC and RDF translators.Despite the unfortunate nomenclature, this object is not the same thing as the object returned by getTranslators(..)or by 188BET靠谱吗Zotero.loadTranslator().
  • translator.translate()
    Runs the translator on the given input.
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