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 WSO2 Data Services Server provides a set of built-in validators for some of the most common use cases. It also provides an extension mechanism where custom validators can be written. For details on custom validators, refer to the Custom section.
Validators have to be added to individual input mappings in a query. Follow the instructions below to add built-in/custom input validators.
1) Click Add New Query link in the Queries page.
The Queries page appears when creating a Data Service. For steps upto opening the Queries page, refer to sub sections in: Create a Data Service Using Various Data Sources.
2) In the Add New Query page that appears, provide the QueryID and DataSource.
The Input Mappings section opens.
3) Click the Add New Input Mapping link.
4) The Add Input Mapping page opens. The Validator drop-down menu contains four built-in validators and the custom validator option.
Built-In Input Validators
Explained below are the pre-defined, standard validators available in the WSO2 Data Services Server.
Long Range Validator
Validates an integer value and checks if it is in the specified range. The validator requires minimum and the maximum values of the range to be validated. For example,
Double Range Validator
Validates a floating point value and checks if it is in the specified range. The validator requires minimum and the maximum values of the range to be validated. For example, 
Length Validator
Validates the string length of a given parameter. The length should be given for validation. For example, 
Pattern Validator
Validates the string value of the parameter against a given regular expression. If the regular expression matches the target parameter, the validator succeeds; else it fails. The validator requires the regular expression to be passed in for validation. 
Custom Validators
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