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| </div><div id='content' class='page-1'><div class='row'><div class='row-fluid'><div class='col-lg-3'><ul class='nav-sidebar'><li class='active'><a href='#doc'>GEP-7</a></li><li><a href='#_abstract' class='anchor-link'>Abstract</a></li><li><a href='#_rationale' class='anchor-link'>Rationale</a></li><li><a href='#_references_and_useful_links' class='anchor-link'>References and useful links</a></li><li><a href='#_update_history' class='anchor-link'>Update history</a></li></ul></div><div class='col-lg-8 col-lg-pull-0'><a name='doc'></a><h1>GEP-7</h1><p>Author: <i/></p><hr/><div id="preamble"> |
| <div class="sectionbody"> |
| <div class="sidebarblock"> |
| <div class="content"> |
| <div class="title">Metadata</div> |
| <div class="hdlist"> |
| <table> |
| <tr> |
| <td class="hdlist1"> |
| <strong>Number</strong> |
| </td> |
| <td class="hdlist2"> |
| <p>GEP-7</p> |
| </td> |
| </tr> |
| <tr> |
| <td class="hdlist1"> |
| <strong>Title</strong> |
| </td> |
| <td class="hdlist2"> |
| <p>JSON Support</p> |
| </td> |
| </tr> |
| <tr> |
| <td class="hdlist1"> |
| <strong>Version</strong> |
| </td> |
| <td class="hdlist2"> |
| <p>4</p> |
| </td> |
| </tr> |
| <tr> |
| <td class="hdlist1"> |
| <strong>Type</strong> |
| </td> |
| <td class="hdlist2"> |
| <p>Feature</p> |
| </td> |
| </tr> |
| <tr> |
| <td class="hdlist1"> |
| <strong>Status</strong> |
| </td> |
| <td class="hdlist2"> |
| <p>Final</p> |
| </td> |
| </tr> |
| <tr> |
| <td class="hdlist1"> |
| <strong>Comment</strong> |
| </td> |
| <td class="hdlist2"> |
| <p>Delivered in Groovy 1.8</p> |
| </td> |
| </tr> |
| <tr> |
| <td class="hdlist1"> |
| <strong>Leader</strong> |
| </td> |
| <td class="hdlist2"> |
| <p>Guillaume Laforge</p> |
| </td> |
| </tr> |
| <tr> |
| <td class="hdlist1"> |
| <strong>Contributors</strong> |
| </td> |
| <td class="hdlist2"> |
| <p>Andres Almiray</p> |
| </td> |
| </tr> |
| <tr> |
| <td class="hdlist1"> |
| <strong>Created</strong> |
| </td> |
| <td class="hdlist2"> |
| <p>2010-10-25</p> |
| </td> |
| </tr> |
| <tr> |
| <td class="hdlist1"> |
| <strong>Last modification</strong>  |
| </td> |
| <td class="hdlist2"> |
| <p>2018-10-12</p> |
| </td> |
| </tr> |
| </table> |
| </div> |
| </div> |
| </div> |
| </div> |
| </div> |
| <div class="sect1"> |
| <h2 id="_abstract">Abstract</h2> |
| <div class="sectionbody"> |
| <div class="paragraph"> |
| <p>Provide a builder/slurper combination for handling data in JSON format in a similar fashion as it’s already done for XML.</p> |
| </div> |
| </div> |
| </div> |
| <div class="sect1"> |
| <h2 id="_rationale">Rationale</h2> |
| <div class="sectionbody"> |
| <div class="paragraph"> |
| <p>JSON has become ubiquitous to the web. RESTful services exchange data in both POX (Plain Old XML) and JSON formats. |
| Groovy has excellent support for producing/consuming XML with MarkupBuilder, XmlSlurper and XmlParser but lacks this |
| kind support for JSON. This GEP strives to remedy the situation, by providing a compatible builder approach.</p> |
| </div> |
| <div class="sect2"> |
| <h3 id="_producing_json">Producing JSON</h3> |
| <div class="paragraph"> |
| <p>The following builder syntax is proposed</p> |
| </div> |
| <div class="listingblock"> |
| <div class="content"> |
| <pre class="prettyprint highlight"><code>def builder = new groovy.json.JsonBuilder() |
| def root = builder.people { |
| person { |
| firstName 'Guillame' |
| lastName 'Laforge' |
| // Maps are valid values for objects too |
| address( |
| city: 'Paris', |
| country: 'France', |
| zip: 12345, |
| ) |
| married true |
| conferences 'JavaOne', 'Gr8conf' |
| } |
| } |
| |
| // creates a data structure made of maps (Json object) and lists (Json array) |
| assert root instanceof Map |
| |
| println builder.toString() |
| |
| // prints (without formatting) |
| {"people": { |
| "person": { |
| "firstName": "Guillaume", |
| "lastName": "Laforge", |
| "address": { |
| "city": "Paris", |
| "country": "France", |
| "zip": 12345 |
| }, |
| "married": true, |
| "conferences": [ |
| "JavaOne", |
| "Gr8conf" |
| ] |
| } |
| }</code></pre> |
| </div> |
| </div> |
| <div class="paragraph"> |
| <p>Valid node values are: <code>Number</code>, <code>String</code>, <code>GString</code>, <code>Boolean</code>, <code>Map</code>, <code>List</code>. <code>null</code> is reserved for object references. |
| Arrays can not be null but they can be empty. Anything else results in an IAE (or a more specialized exception) being thrown.</p> |
| </div> |
| </div> |
| <div class="sect2"> |
| <h3 id="_special_cases">Special cases</h3> |
| <div class="paragraph"> |
| <p>There is a special case to be considered: when the top node results in an anonymous object or array. |
| or objects a call() method on the builder is needed which takes a map as argument, for arrays call() takes a vararg of values. Here are some examples:</p> |
| </div> |
| <div class="listingblock"> |
| <div class="content"> |
| <pre class="prettyprint highlight"><code>builder.foo "foo" |
| // produces |
| {foo: "foo"}</code></pre> |
| </div> |
| </div> |
| <div class="listingblock"> |
| <div class="content"> |
| <pre class="prettyprint highlight"><code>builder([{ |
| foo 'foo' |
| }]) |
| // produces |
| [{"foo": "foo"}]</code></pre> |
| </div> |
| </div> |
| <div class="listingblock"> |
| <div class="content"> |
| <pre class="prettyprint highlight"><code>builder([[ |
| foo: 'foo' |
| ]]) |
| // produces, same as above |
| [{"foo": "foo"}]</code></pre> |
| </div> |
| </div> |
| <div class="listingblock"> |
| <div class="content"> |
| <pre class="prettyprint highlight"><code>builder { |
| elem 1, 2, 3 |
| } |
| // produces |
| { "elem": [1, 2, 3] }</code></pre> |
| </div> |
| </div> |
| <div class="paragraph"> |
| <p>When a method is called on the builder without arguments, and empty JSON object is associated with the key:</p> |
| </div> |
| <div class="listingblock"> |
| <div class="content"> |
| <pre class="prettyprint highlight"><code>builder.element() |
| // produces |
| { "element": {} }</code></pre> |
| </div> |
| </div> |
| <div class="paragraph"> |
| <p>You can also pass a map and a closure argument:</p> |
| </div> |
| <div class="listingblock"> |
| <div class="content"> |
| <pre class="prettyprint highlight"><code>builder.person(name: "Guillaume", age: 33) { town "Paris" } |
| |
| // produces |
| {"name": "Guillaume", "age": 33, "town": "Paris}</code></pre> |
| </div> |
| </div> |
| <div class="paragraph"> |
| <p>Calls like the following, with a map and a value, don’t have any meaningful representation in JSON (unlike in XML), and triggers a JsonException:</p> |
| </div> |
| <div class="listingblock"> |
| <div class="content"> |
| <pre class="prettyprint highlight"><code>shouldFail(JsonException) { |
| builder.elem(a: 1, b: 2, "some text value") |
| }</code></pre> |
| </div> |
| </div> |
| <div class="paragraph"> |
| <p>In case of overlapping keys in the map and the closure, the closure wins – a visual clue for this rule is that the closure appears "after" the map key/value pairs.</p> |
| </div> |
| <div class="paragraph"> |
| <p>Consuming JSON |
| The proposal is for the creation of a JsonSlurper class that can read JSON from a string (in a non-streaming fashion) and produce a hierarchy of maps and lists representing the JSON objects and arrays respectively.</p> |
| </div> |
| <div class="listingblock"> |
| <div class="content"> |
| <pre class="prettyprint highlight"><code>String json = '{"person": {"firstName": "Guillaume", "lastName": "Laforge", "conferences": ["JavaOne", "Gr8conf"]}}' |
| def root = new JsonSlurper().parseText(json) |
| assert root instanceof Map |
| assert root.person.conferences instanceof List |
| assert root.person.firstName == 'Guillaume' |
| assert root.person.conferences[1] == 'Gr8conf'</code></pre> |
| </div> |
| </div> |
| <div class="paragraph"> |
| <p>JsonSlurper’s API should mirror closely what XmlParser/XmlSlurper offers in terms of its parse* method variants.</p> |
| </div> |
| </div> |
| </div> |
| </div> |
| <div class="sect1"> |
| <h2 id="_references_and_useful_links">References and useful links</h2> |
| <div class="sectionbody"> |
| <div class="paragraph"> |
| <p>JSON Spec and Java implementations</p> |
| </div> |
| <div class="ulist"> |
| <ul> |
| <li> |
| <p><a href="http://json.org/">json.org</a></p> |
| </li> |
| <li> |
| <p><a href="http://tools.ietf.org/html/rfc4627">RFC-4627</a></p> |
| </li> |
| <li> |
| <p><a href="http://json-lib.sourceforge.net/">json-lib</a></p> |
| </li> |
| </ul> |
| </div> |
| <div class="sect2"> |
| <h3 id="_mailing_list_discussions">Mailing-list discussions</h3> |
| <div class="ulist"> |
| <ul> |
| <li> |
| <p><a href="https://markmail.org/thread/5ofqwr6t33okyh6g">groovy-dev: Built-in JSON support in 1.8</a></p> |
| </li> |
| </ul> |
| </div> |
| </div> |
| <div class="sect2"> |
| <h3 id="_jira_issues">JIRA issues</h3> |
| <div class="ulist"> |
| <ul> |
| <li> |
| <p><a href="https://issues.apache.org/jira/browse/GROOVY-4644">GROOVY-4644: JSON support: provide a parser and a builder for JSON content</a></p> |
| </li> |
| </ul> |
| </div> |
| </div> |
| </div> |
| </div> |
| <div class="sect1"> |
| <h2 id="_update_history">Update history</h2> |
| <div class="sectionbody"> |
| <div class="dlist"> |
| <dl> |
| <dt class="hdlist1">3 (2011-02-02)</dt> |
| <dd> |
| <p>Version as extracted from Codehaus wiki</p> |
| </dd> |
| <dt class="hdlist1">4 (2018-10-16)</dt> |
| <dd> |
| <p>Numerous minor tweaks</p> |
| </dd> |
| </dl> |
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