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ScalaValidationCookbook.html
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Introduction
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Features
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<li class="chapter " data-level="1.2.1" data-path="ScalaValidationRule.html">
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Validating and transforming data
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Combining Rules
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Serializing data with Write
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Combining Writes
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Validation Inception
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Exporting Validations to Javascript using Scala.js
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Extensions: Supporting new types
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Cookbook
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Play's Form API migration
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Play's Json API migration
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<h1 id="cookbook">Cookbook</h1>
<blockquote>
<p>All the examples below are validating Json objects. The API is not dedicated only to Json, it can be used on any type. Please refer to <a href="ScalaValidationJson.md">Validating Json</a>, <a href="ScalaValidationMigrationForm.html">Validating Forms</a>, and <a href="ScalaValidationExtensions.html">Supporting new types</a> for more information.</p>
</blockquote>
<h2 id="rule"><code>Rule</code></h2>
<h3 id="typical-case-class-validation">Typical case class validation</h3>
<pre><code class="lang-scala"><span class="hljs-keyword">import</span> jto.validation._
<span class="hljs-keyword">import</span> play.api.libs.json._
<span class="hljs-keyword">case</span> <span class="hljs-class"><span class="hljs-keyword">class</span> <span class="hljs-title">Creature</span>(<span class="hljs-params">
name: <span class="hljs-type">String</span>,
isDead: <span class="hljs-type">Boolean</span>,
weight: <span class="hljs-type">Float</span></span>)</span>
<span class="hljs-keyword">implicit</span> <span class="hljs-keyword">val</span> creatureRule: <span class="hljs-type">Rule</span>[<span class="hljs-type">JsValue</span>, <span class="hljs-type">Creature</span>] = <span class="hljs-type">From</span>[<span class="hljs-type">JsValue</span>] { __ =>
<span class="hljs-keyword">import</span> jto.validation.playjson.<span class="hljs-type">Rules</span>._
((__ \ <span class="hljs-string">"name"</span>).read[<span class="hljs-type">String</span>] ~
(__ \ <span class="hljs-string">"isDead"</span>).read[<span class="hljs-type">Boolean</span>] ~
(__ \ <span class="hljs-string">"weight"</span>).read[<span class="hljs-type">Float</span>])(<span class="hljs-type">Creature</span>.apply)
}
</code></pre>
<pre><code class="lang-scala">scala> <span class="hljs-keyword">val</span> js = <span class="hljs-type">Json</span>.obj( <span class="hljs-string">"name"</span> -> <span class="hljs-string">"gremlins"</span>, <span class="hljs-string">"isDead"</span> -> <span class="hljs-literal">false</span>, <span class="hljs-string">"weight"</span> -> <span class="hljs-number">1.0</span>f)
js: play.api.libs.json.<span class="hljs-type">JsObject</span> = {<span class="hljs-string">"name"</span>:<span class="hljs-string">"gremlins"</span>,<span class="hljs-string">"isDead"</span>:<span class="hljs-literal">false</span>,<span class="hljs-string">"weight"</span>:<span class="hljs-number">1</span>}
scala> <span class="hljs-type">From</span>[<span class="hljs-type">JsValue</span>, <span class="hljs-type">Creature</span>](js)
res2: jto.validation.<span class="hljs-type">VA</span>[<span class="hljs-type">Creature</span>] = <span class="hljs-type">Valid</span>(<span class="hljs-type">Creature</span>(gremlins,<span class="hljs-literal">false</span>,<span class="hljs-number">1.0</span>))
scala> <span class="hljs-type">From</span>[<span class="hljs-type">JsValue</span>, <span class="hljs-type">Creature</span>](<span class="hljs-type">Json</span>.obj())
res3: jto.validation.<span class="hljs-type">VA</span>[<span class="hljs-type">Creature</span>] = <span class="hljs-type">Invalid</span>(<span class="hljs-type">List</span>((/name,<span class="hljs-type">List</span>(<span class="hljs-type">ValidationError</span>(<span class="hljs-type">List</span>(error.required),<span class="hljs-type">WrappedArray</span>()))), (/isDead,<span class="hljs-type">List</span>(<span class="hljs-type">ValidationError</span>(<span class="hljs-type">List</span>(error.required),<span class="hljs-type">WrappedArray</span>()))), (/weight,<span class="hljs-type">List</span>(<span class="hljs-type">ValidationError</span>(<span class="hljs-type">List</span>(error.required),<span class="hljs-type">WrappedArray</span>())))))
</code></pre>
<h3 id="dependent-values">Dependent values</h3>
<p>A common example of this use case is the validation of <code>password</code> and <code>password confirmation</code> fields in a signup form.</p>
<ol>
<li>First, you need to validate that each field is valid independently</li>
<li>Then, given the two values, you need to validate that they are equals.</li>
</ol>
<pre><code class="lang-scala"><span class="hljs-keyword">import</span> jto.validation._
<span class="hljs-keyword">import</span> play.api.libs.json._
<span class="hljs-keyword">val</span> passRule: <span class="hljs-type">Rule</span>[<span class="hljs-type">JsValue</span>, <span class="hljs-type">String</span>] = <span class="hljs-type">From</span>[<span class="hljs-type">JsValue</span>] { __ =>
<span class="hljs-keyword">import</span> jto.validation.playjson.<span class="hljs-type">Rules</span>._
<span class="hljs-comment">// This code creates a `Rule[JsValue, (String, String)]` each of of the String must be non-empty</span>
((__ \ <span class="hljs-string">"password"</span>).read(notEmpty) ~
(__ \ <span class="hljs-string">"verify"</span>).read(notEmpty)).tupled
<span class="hljs-comment">// We then create a `Rule[(String, String), String]` validating that given a `(String, String)`,</span>
<span class="hljs-comment">// both strings are equals. Those rules are then composed together.</span>
.andThen(<span class="hljs-type">Rule</span>.uncurry(equalTo[<span class="hljs-type">String</span>])
<span class="hljs-comment">// In case of `Invalid`, we want to control the field holding the errors.</span>
<span class="hljs-comment">// We change the `Path` of errors using `repath`</span>
.repath(_ => (<span class="hljs-type">Path</span> \ <span class="hljs-string">"verify"</span>))
)
}
</code></pre>
<p>Let's test it:</p>
<pre><code class="lang-scala">scala> passRule.validate(<span class="hljs-type">Json</span>.obj(<span class="hljs-string">"password"</span> -> <span class="hljs-string">"foo"</span>, <span class="hljs-string">"verify"</span> -> <span class="hljs-string">"foo"</span>))
res5: jto.validation.<span class="hljs-type">VA</span>[<span class="hljs-type">String</span>] = <span class="hljs-type">Valid</span>(foo)
scala> passRule.validate(<span class="hljs-type">Json</span>.obj(<span class="hljs-string">"password"</span> -> <span class="hljs-string">""</span>, <span class="hljs-string">"verify"</span> -> <span class="hljs-string">"foo"</span>))
res6: jto.validation.<span class="hljs-type">VA</span>[<span class="hljs-type">String</span>] = <span class="hljs-type">Invalid</span>(<span class="hljs-type">List</span>((/password,<span class="hljs-type">List</span>(<span class="hljs-type">ValidationError</span>(<span class="hljs-type">List</span>(error.required),<span class="hljs-type">WrappedArray</span>())))))
scala> passRule.validate(<span class="hljs-type">Json</span>.obj(<span class="hljs-string">"password"</span> -> <span class="hljs-string">"foo"</span>, <span class="hljs-string">"verify"</span> -> <span class="hljs-string">""</span>))
res7: jto.validation.<span class="hljs-type">VA</span>[<span class="hljs-type">String</span>] = <span class="hljs-type">Invalid</span>(<span class="hljs-type">List</span>((/verify,<span class="hljs-type">List</span>(<span class="hljs-type">ValidationError</span>(<span class="hljs-type">List</span>(error.required),<span class="hljs-type">WrappedArray</span>())))))
scala> passRule.validate(<span class="hljs-type">Json</span>.obj(<span class="hljs-string">"password"</span> -> <span class="hljs-string">""</span>, <span class="hljs-string">"verify"</span> -> <span class="hljs-string">""</span>))
res8: jto.validation.<span class="hljs-type">VA</span>[<span class="hljs-type">String</span>] = <span class="hljs-type">Invalid</span>(<span class="hljs-type">List</span>((/password,<span class="hljs-type">List</span>(<span class="hljs-type">ValidationError</span>(<span class="hljs-type">List</span>(error.required),<span class="hljs-type">WrappedArray</span>()))), (/verify,<span class="hljs-type">List</span>(<span class="hljs-type">ValidationError</span>(<span class="hljs-type">List</span>(error.required),<span class="hljs-type">WrappedArray</span>())))))
scala> passRule.validate(<span class="hljs-type">Json</span>.obj(<span class="hljs-string">"password"</span> -> <span class="hljs-string">"foo"</span>, <span class="hljs-string">"verify"</span> -> <span class="hljs-string">"bar"</span>))
res9: jto.validation.<span class="hljs-type">VA</span>[<span class="hljs-type">String</span>] = <span class="hljs-type">Invalid</span>(<span class="hljs-type">List</span>((/verify,<span class="hljs-type">List</span>(<span class="hljs-type">ValidationError</span>(<span class="hljs-type">List</span>(error.equals),<span class="hljs-type">WrappedArray</span>(foo))))))
</code></pre>
<h3 id="recursive-types">Recursive types</h3>
<p>When validating recursive types:</p>
<ul>
<li>Use the <code>lazy</code> keyword to allow forward reference.</li>
<li>As with any recursive definition, the type of the <code>Rule</code> <strong>must</strong> be explicitly given.</li>
</ul>
<pre><code class="lang-scala"><span class="hljs-keyword">case</span> <span class="hljs-class"><span class="hljs-keyword">class</span> <span class="hljs-title">User</span>(<span class="hljs-params">
name: <span class="hljs-type">String</span>,
age: <span class="hljs-type">Int</span>,
email: <span class="hljs-type">Option</span>[<span class="hljs-type">String</span>],
isAlive: <span class="hljs-type">Boolean</span>,
friend: <span class="hljs-type">Option</span>[<span class="hljs-type">User</span>]</span>)</span>
</code></pre>
<pre><code class="lang-scala"><span class="hljs-keyword">import</span> jto.validation._
<span class="hljs-keyword">import</span> play.api.libs.json._
<span class="hljs-comment">// Note the lazy keyword</span>
<span class="hljs-keyword">implicit</span> <span class="hljs-keyword">lazy</span> <span class="hljs-keyword">val</span> userRule: <span class="hljs-type">Rule</span>[<span class="hljs-type">JsValue</span>, <span class="hljs-type">User</span>] = <span class="hljs-type">From</span>[<span class="hljs-type">JsValue</span>] { __ =>
<span class="hljs-keyword">import</span> jto.validation.playjson.<span class="hljs-type">Rules</span>._
((__ \ <span class="hljs-string">"name"</span>).read[<span class="hljs-type">String</span>] ~
(__ \ <span class="hljs-string">"age"</span>).read[<span class="hljs-type">Int</span>] ~
(__ \ <span class="hljs-string">"email"</span>).read[<span class="hljs-type">Option</span>[<span class="hljs-type">String</span>]] ~
(__ \ <span class="hljs-string">"isAlive"</span>).read[<span class="hljs-type">Boolean</span>] ~
(__ \ <span class="hljs-string">"friend"</span>).read[<span class="hljs-type">Option</span>[<span class="hljs-type">User</span>]])(<span class="hljs-type">User</span>.apply)
}
</code></pre>
<p>or using macros:</p>
<pre><code class="lang-scala">scala> <span class="hljs-keyword">import</span> jto.validation._
<span class="hljs-keyword">import</span> jto.validation._
scala> <span class="hljs-keyword">import</span> play.api.libs.json._
<span class="hljs-keyword">import</span> play.api.libs.json._
scala> <span class="hljs-keyword">import</span> jto.validation.playjson.<span class="hljs-type">Rules</span>._
<span class="hljs-keyword">import</span> jto.validation.playjson.<span class="hljs-type">Rules</span>._
scala> <span class="hljs-comment">// Note the lazy keyword, and the explicit typing</span>
| <span class="hljs-keyword">implicit</span> <span class="hljs-keyword">lazy</span> <span class="hljs-keyword">val</span> userRule: <span class="hljs-type">Rule</span>[<span class="hljs-type">JsValue</span>, <span class="hljs-type">User</span>] = <span class="hljs-type">Rule</span>.gen[<span class="hljs-type">JsValue</span>, <span class="hljs-type">User</span>]
userRule: jto.validation.<span class="hljs-type">Rule</span>[play.api.libs.json.<span class="hljs-type">JsValue</span>,<span class="hljs-type">User</span>] = <<span class="hljs-keyword">lazy</span>>
</code></pre>
<h3 id="read-keys">Read keys</h3>
<pre><code class="lang-scala">import jto.validation._
import play.api.libs.json._
val js = Json.parse("""
{
"values": [
{ "foo": "bar" },
{ "bar": "baz" }
]
}
""")
val r: Rule[JsValue, Seq[(String, String)]] = From[JsValue] { __ =>
import jto.validation.playjson.Rules._
val tupleR: Rule[JsValue, (String, String)] = Rule.fromMapping[JsValue, (String, String)] {
case JsObject(Seq((key, JsString(value)))) => Valid(key.toString -> value)
case _ => Invalid(Seq(ValidationError("BAAAM")))
}
(__ \ "values").read(seqR(tupleR))
}
</code></pre>
<pre><code class="lang-scala">scala> r.validate(js)
res15: jto.validation.<span class="hljs-type">VA</span>[<span class="hljs-type">Seq</span>[(<span class="hljs-type">String</span>, <span class="hljs-type">String</span>)]] = <span class="hljs-type">Invalid</span>(<span class="hljs-type">List</span>((/values[<span class="hljs-number">0</span>],<span class="hljs-type">List</span>(<span class="hljs-type">ValidationError</span>(<span class="hljs-type">List</span>(<span class="hljs-type">BAAAM</span>),<span class="hljs-type">WrappedArray</span>()))), (/values[<span class="hljs-number">1</span>],<span class="hljs-type">List</span>(<span class="hljs-type">ValidationError</span>(<span class="hljs-type">List</span>(<span class="hljs-type">BAAAM</span>),<span class="hljs-type">WrappedArray</span>())))))
</code></pre>
<h3 id="validate-subclasses-and-parse-the-concrete-class">Validate subclasses (and parse the concrete class)</h3>
<p>Consider the following class definitions:</p>
<pre><code class="lang-scala"><span class="hljs-class"><span class="hljs-keyword">trait</span> <span class="hljs-title">A</span></span>
<span class="hljs-keyword">case</span> <span class="hljs-class"><span class="hljs-keyword">class</span> <span class="hljs-title">B</span>(<span class="hljs-params">foo: <span class="hljs-type">Int</span></span>) <span class="hljs-keyword">extends</span> <span class="hljs-title">A</span></span>
<span class="hljs-keyword">case</span> <span class="hljs-class"><span class="hljs-keyword">class</span> <span class="hljs-title">C</span>(<span class="hljs-params">bar: <span class="hljs-type">Int</span></span>) <span class="hljs-keyword">extends</span> <span class="hljs-title">A</span></span>
<span class="hljs-keyword">val</span> b = <span class="hljs-type">Json</span>.obj(<span class="hljs-string">"name"</span> -> <span class="hljs-string">"B"</span>, <span class="hljs-string">"foo"</span> -> <span class="hljs-number">4</span>)
<span class="hljs-keyword">val</span> c = <span class="hljs-type">Json</span>.obj(<span class="hljs-string">"name"</span> -> <span class="hljs-string">"C"</span>, <span class="hljs-string">"bar"</span> -> <span class="hljs-number">6</span>)
<span class="hljs-keyword">val</span> e = <span class="hljs-type">Json</span>.obj(<span class="hljs-string">"name"</span> -> <span class="hljs-string">"E"</span>, <span class="hljs-string">"eee"</span> -> <span class="hljs-number">6</span>)
</code></pre>
<h4 id="trying-all-the-possible-rules-implementations">Trying all the possible rules implementations</h4>
<pre><code class="lang-scala"><span class="hljs-keyword">import</span> cats.syntax.cartesian._
<span class="hljs-keyword">val</span> rb: <span class="hljs-type">Rule</span>[<span class="hljs-type">JsValue</span>, <span class="hljs-type">A</span>] = <span class="hljs-type">From</span>[<span class="hljs-type">JsValue</span>] { __ =>
<span class="hljs-keyword">import</span> jto.validation.playjson.<span class="hljs-type">Rules</span>._
(__ \ <span class="hljs-string">"name"</span>).read(equalTo(<span class="hljs-string">"B"</span>)) *> (__ \ <span class="hljs-string">"foo"</span>).read[<span class="hljs-type">Int</span>].map(<span class="hljs-type">B</span>.apply)
}
<span class="hljs-keyword">val</span> rc: <span class="hljs-type">Rule</span>[<span class="hljs-type">JsValue</span>, <span class="hljs-type">A</span>] = <span class="hljs-type">From</span>[<span class="hljs-type">JsValue</span>] { __ =>
<span class="hljs-keyword">import</span> jto.validation.playjson.<span class="hljs-type">Rules</span>._
(__ \ <span class="hljs-string">"name"</span>).read(equalTo(<span class="hljs-string">"C"</span>)) *> (__ \ <span class="hljs-string">"bar"</span>).read[<span class="hljs-type">Int</span>].map(<span class="hljs-type">C</span>.apply)
}
<span class="hljs-keyword">val</span> typeInvalid = <span class="hljs-type">Invalid</span>(<span class="hljs-type">Seq</span>(<span class="hljs-type">Path</span> -> <span class="hljs-type">Seq</span>(<span class="hljs-type">ValidationError</span>(<span class="hljs-string">"validation.unknownType"</span>))))
<span class="hljs-keyword">val</span> rule = rb orElse rc orElse <span class="hljs-type">Rule</span>(_ => typeInvalid)
</code></pre>
<pre><code class="lang-scala">scala> rule.validate(b)
res20: jto.validation.<span class="hljs-type">VA</span>[<span class="hljs-type">A</span>] = <span class="hljs-type">Valid</span>(<span class="hljs-type">B</span>(<span class="hljs-number">4</span>))
scala> rule.validate(c)
res21: jto.validation.<span class="hljs-type">VA</span>[<span class="hljs-type">A</span>] = <span class="hljs-type">Valid</span>(<span class="hljs-type">C</span>(<span class="hljs-number">6</span>))
scala> rule.validate(e)
res22: jto.validation.<span class="hljs-type">VA</span>[<span class="hljs-type">A</span>] = <span class="hljs-type">Invalid</span>(<span class="hljs-type">List</span>((/,<span class="hljs-type">List</span>(<span class="hljs-type">ValidationError</span>(<span class="hljs-type">List</span>(validation.unknownType),<span class="hljs-type">WrappedArray</span>())))))
</code></pre>
<h4 id="using-class-discovery-based-on-field-discrimination">Using class discovery based on field discrimination</h4>
<pre><code class="lang-scala"><span class="hljs-keyword">val</span> typeInvalid = <span class="hljs-type">Invalid</span>(<span class="hljs-type">Seq</span>(<span class="hljs-type">Path</span> -> <span class="hljs-type">Seq</span>(<span class="hljs-type">ValidationError</span>(<span class="hljs-string">"validation.unknownType"</span>))))
<span class="hljs-keyword">val</span> rule: <span class="hljs-type">Rule</span>[<span class="hljs-type">JsValue</span>, <span class="hljs-type">A</span>] = <span class="hljs-type">From</span>[<span class="hljs-type">JsValue</span>] { __ =>
<span class="hljs-keyword">import</span> jto.validation.playjson.<span class="hljs-type">Rules</span>._
(__ \ <span class="hljs-string">"name"</span>).read[<span class="hljs-type">String</span>].flatMap[<span class="hljs-type">A</span>] {
<span class="hljs-keyword">case</span> <span class="hljs-string">"B"</span> => (__ \ <span class="hljs-string">"foo"</span>).read[<span class="hljs-type">Int</span>].map(<span class="hljs-type">B</span>.apply _)
<span class="hljs-keyword">case</span> <span class="hljs-string">"C"</span> => (__ \ <span class="hljs-string">"bar"</span>).read[<span class="hljs-type">Int</span>].map(<span class="hljs-type">C</span>.apply _)
<span class="hljs-keyword">case</span> _ => <span class="hljs-type">Rule</span>(_ => typeInvalid)
}
}
</code></pre>
<pre><code class="lang-scala">scala> rule.validate(b)
res24: jto.validation.<span class="hljs-type">VA</span>[<span class="hljs-type">A</span>] = <span class="hljs-type">Valid</span>(<span class="hljs-type">B</span>(<span class="hljs-number">4</span>))
scala> rule.validate(c)
res25: jto.validation.<span class="hljs-type">VA</span>[<span class="hljs-type">A</span>] = <span class="hljs-type">Valid</span>(<span class="hljs-type">C</span>(<span class="hljs-number">6</span>))
scala> rule.validate(e)
res26: jto.validation.<span class="hljs-type">VA</span>[<span class="hljs-type">A</span>] = <span class="hljs-type">Invalid</span>(<span class="hljs-type">List</span>((/,<span class="hljs-type">List</span>(<span class="hljs-type">ValidationError</span>(<span class="hljs-type">List</span>(validation.unknownType),<span class="hljs-type">WrappedArray</span>())))))
</code></pre>
<h2 id="write"><code>Write</code></h2>
<h3 id="typical-case-class-write">typical case class <code>Write</code></h3>
<pre><code class="lang-scala"><span class="hljs-keyword">import</span> jto.validation._
<span class="hljs-keyword">import</span> play.api.libs.json._
<span class="hljs-keyword">import</span> scala.<span class="hljs-type">Function</span>.unlift
<span class="hljs-keyword">case</span> <span class="hljs-class"><span class="hljs-keyword">class</span> <span class="hljs-title">Creature</span>(<span class="hljs-params">
name: <span class="hljs-type">String</span>,
isDead: <span class="hljs-type">Boolean</span>,
weight: <span class="hljs-type">Float</span></span>)</span>
<span class="hljs-keyword">implicit</span> <span class="hljs-keyword">val</span> creatureWrite = <span class="hljs-type">To</span>[<span class="hljs-type">JsObject</span>] { __ =>
<span class="hljs-keyword">import</span> jto.validation.playjson.<span class="hljs-type">Writes</span>._
((__ \ <span class="hljs-string">"name"</span>).write[<span class="hljs-type">String</span>] ~
(__ \ <span class="hljs-string">"isDead"</span>).write[<span class="hljs-type">Boolean</span>] ~
(__ \ <span class="hljs-string">"weight"</span>).write[<span class="hljs-type">Float</span>])(unlift(<span class="hljs-type">Creature</span>.unapply))
}
</code></pre>
<pre><code class="lang-scala">scala> <span class="hljs-type">To</span>[<span class="hljs-type">Creature</span>, <span class="hljs-type">JsObject</span>](<span class="hljs-type">Creature</span>(<span class="hljs-string">"gremlins"</span>, <span class="hljs-literal">false</span>, <span class="hljs-number">1</span>f))
res29: play.api.libs.json.<span class="hljs-type">JsObject</span> = {<span class="hljs-string">"name"</span>:<span class="hljs-string">"gremlins"</span>,<span class="hljs-string">"isDead"</span>:<span class="hljs-literal">false</span>,<span class="hljs-string">"weight"</span>:<span class="hljs-number">1</span>}
</code></pre>
<h3 id="adding-static-values-to-a-write">Adding static values to a <code>Write</code></h3>
<pre><code class="lang-scala"><span class="hljs-keyword">import</span> jto.validation._
<span class="hljs-keyword">import</span> play.api.libs.json._
<span class="hljs-keyword">case</span> <span class="hljs-class"><span class="hljs-keyword">class</span> <span class="hljs-title">LatLong</span>(<span class="hljs-params">lat: <span class="hljs-type">Float</span>, long: <span class="hljs-type">Float</span></span>)</span>
<span class="hljs-keyword">implicit</span> <span class="hljs-keyword">val</span> latLongWrite = {
<span class="hljs-keyword">import</span> jto.validation.playjson.<span class="hljs-type">Writes</span>._
<span class="hljs-type">To</span>[<span class="hljs-type">JsObject</span>] { __ =>
((__ \ <span class="hljs-string">"lat"</span>).write[<span class="hljs-type">Float</span>] ~
(__ \ <span class="hljs-string">"long"</span>).write[<span class="hljs-type">Float</span>])(unlift(<span class="hljs-type">LatLong</span>.unapply))
}
}
<span class="hljs-keyword">case</span> <span class="hljs-class"><span class="hljs-keyword">class</span> <span class="hljs-title">Point</span>(<span class="hljs-params">coords: <span class="hljs-type">LatLong</span></span>)</span>
<span class="hljs-keyword">implicit</span> <span class="hljs-keyword">val</span> pointWrite = {
<span class="hljs-keyword">import</span> jto.validation.playjson.<span class="hljs-type">Writes</span>._
<span class="hljs-type">To</span>[<span class="hljs-type">JsObject</span>] { __ =>
((__ \ <span class="hljs-string">"coords"</span>).write[<span class="hljs-type">LatLong</span>] ~
(__ \ <span class="hljs-string">"type"</span>).write[<span class="hljs-type">String</span>]) ((_: <span class="hljs-type">Point</span>).coords -> <span class="hljs-string">"point"</span>)
}
}
</code></pre>
<pre><code class="lang-scala">scala> <span class="hljs-keyword">val</span> p = <span class="hljs-type">Point</span>(<span class="hljs-type">LatLong</span>(<span class="hljs-number">123.3</span>F, <span class="hljs-number">334.5</span>F))
p: <span class="hljs-type">Point</span> = <span class="hljs-type">Point</span>(<span class="hljs-type">LatLong</span>(<span class="hljs-number">123.3</span>,<span class="hljs-number">334.5</span>))
scala> pointWrite.writes(p)
res34: play.api.libs.json.<span class="hljs-type">JsObject</span> = {<span class="hljs-string">"coords"</span>:{<span class="hljs-string">"lat"</span>:<span class="hljs-number">123.3</span>,<span class="hljs-string">"long"</span>:<span class="hljs-number">334.5</span>},<span class="hljs-string">"type"</span>:<span class="hljs-string">"point"</span>}
</code></pre>
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