docs/user-manual/modules/ROOT/pages/validator.adoc

= Validator

Validator performs declarative validation of the message according to the declared
_Input Type_ and/or _Output Type_ on a route definition which declares the expected
message type.


== Data type format

[source,text]
----
scheme:name
----

where *scheme* is the type of data model like `java`, `xml` or `json`, and *name* is the individual
data type name.

== Supported Validators

[width="100%",cols="25%,75%",options="header",]
|===
| Validator | Description
| Predicate Validator | Validate with using Expression or Predicate
| Endpoint Validator | Validate by forwarding to the Endpoint to be used with validation component such as Validation Component or Bean Validation Component.
| Custom Validator | Validate with using custom validator class. Validator must be a subclass of `org.apache.camel.spi.Validator`
|===


== Common Options
All validators have following common options to specify which data type is supported by the validator.
`type` must be specified.

[width="100%",cols="25%,75%",options="header",]
|===
| Name | Description
| type | Data type to validate
|===


== Predicate Validator Options

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|===
| Name | Description
| expression | Expression or Predicate to be used for validation
|===

Here is an example to specify a validation predicate:

Java DSL:

[source,java]
----
validator()
    .type("csv:CSVOrder")
    .withExpression(bodyAs(String.class).contains("{name:XOrder}"));
----

XML DSL:

[source,xml]
----
<predicateValidator Type="csv:CSVOrder">
    <simple>${body} contains '{name:XOrder}'</simple>
</predicateValidator>
----

== Endpoint Validator Options

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|===
| Name | Description
| ref | Reference to the Endpoint ID
| uri | Endpoint URI
|===

Here is an example to specify endpoint URI in Java DSL:

[source,java]
----
validator()
    .type("xml")
    .withUri("validator:xsd/schema.xsd");
----

And here is an example to specify endpoint ref in XML DSL:

[source,xml]
----
<endpointValidator uri="validator:xsd/schema.xsd" type="xml"/>
----

Note that the Endpoint Validator just forwards the message to the specified endpoint. In above example,
camel forwards the message to the `validator:` endpoint, which actually is a
xref:components::validator-component.adoc[Validation Component]. You can also use any other validation component like
Bean Validation Component.

== Custom Validator Options

The validator must be an implementation of `org.apache.camel.spi.Validator`

[width="100%",cols="25%,75%",options="header",]
|===
| Name | Description
| ref | Reference to the custom Validator bean ID
| className | Fully qualified class name of the custom Validator class
|===

Here is an example to specify custom Validator class:

Java DSL:

[source,java]
----
validator()
    .type("json")
    .withJava(com.example.MyCustomValidator.class);
----

XML DSL:

[source,xml]
----
<customTransformer className="com.example.MyCustomValidator" type="json"/>
----

== Examples

For example to declare the Endpoint Validator which uses
validator component to validate `xml:ABCOrder`, we can do as follows:

Java DSL:

[source,java]
----
validator()
    .type("xml:ABCOrder")
    .withUri("validator:xsd/schema.xsd");
----

And in XML DSL:

[source,xml]
----
<camelContext id="camel" xmlns="http://camel.apache.org/schema/spring">
    <validators>
        <endpointValidator uri="validator:xsd/schema.xsd" type="xml:ABCOrder"/>
    </validators>
</camelContext>
----

If you have following route definition, above validator will be applied when `direct:abc` endpoint
receives the message. Note that `inputTypeWithValidate` is used instead of `inputType` in Java DSL,
and the `validate` attribute on the inputType declaration is set to `true` in XML DSL:

Java DSL:

[source,java]
----
from("direct:abc")
    .inputTypeWithValidate("xml:ABCOrder")
    .log("${body}");
----

XML DSL:

[source,xml]
----
<camelContext id="camel" xmlns="http://camel.apache.org/schema/spring">
    <route>
        <from uri="direct:abc"/>
        <inputType urn="xml:ABCOrder" validate="true"/>
        <log message="${body}"/>
    </route>
</camelContext>
----

== See Also

The xref:transformer.adoc[Transformer] is a related functionality.