Input Validators

Validators are added to individual input mappings in a query. Input validation allows data services to validate the input parameters in a request and stop the execution of the request if the input doesn’t meet the required criteria. The ESB profile of WSO2 EI provides a set of built-in validators for some of the most common use cases. It also provides an extension mechanism to write custom validators.

Long Range validator

Validates if an integer value is in the specified range. The validator requires a minimum and a maximum value to set the range. For example,

Double Range validator

Validates if a floating point is in the specified range. The validator requires a minimum and a maximum value to set the range. For example,

Length validator

Validates the string length of a given parameter against a specified length. For example,

Pattern validator

Validates the string value of the parameter against a given regular expression. For example,

Custom validators

Used to add your own validation logic by implementing the interface org.wso2.carbon.dataservices.core.validation.Validator. The definition of the interface is as follows:

public interface Validator {
    public void validate(ValidationContext context, String name, ParamValue value) throws ValidationException;
}

If the validation fails, the validate method in the interface by default throws an exception of type ValidationException . The parameters of the method are as follows:

• context : Is of type ValidationContext, which contains information about the full set of parameters passed into the request. When the validation logic depends on other parameters, the validation context can be used to check the names/values of the rest of the parameters.
• name : A string value that represents the name of the parameter to be validated.
• value : Is of type ParamType, which represents the value of the parameter to be validated. It is either SCALAR or ARRAY.

If you need to provide properties when initializing the custom validator, it is necessary to implement the org.wso2.carbon.dataservices.core.validation.ValidatorExt  interface. This extends the Validator interface as shown below.

public interface ValidatorExt extends Validator {
    public void init(Map<String, String> props);
}

After creating a custom validator class, package it in a JAR file and store it in the server's classpath location for external libraries (which is the  <EI_HOME>/lib directory)

What's next?

Want to try out a scenario that includes input validators? Take a look at the Validating Input Values in a Data Request tutorial.