field-policy

Field Policies

Overview

Design Custom Standardization and Validation Rules that can be applied to a Table Field. Standardization and Validation rules are written as simple Java POJO along with custom Annotations that allow the system to transform policies to/from the User Interface.

Below is the mapping of the User Interface Object and its respective to Domain Model

User Interface (UI) class	Domain Class
FieldStandardizationRule	StandardizationPolicy
FieldValidationRule	ValidationPolicy

To understand how the system uses the annotations to automatically transform the objects click here.

Requirements

1. Policy Constructor rules

   The StandardizationPolicy and ValidationPolicy must follow one of the following rules

   1. Have a no arg constructor
   2. or Have a constructor with parameters each annotated with @PolicyPropertyRef (See examples below)
   3. or be a singleton with a private constructor and a public static instance() method (See examples below)

2. Standardization Policies must implement the StandardizationPolicy interface and be annotated with @Standardizer

3. Validator Policies must implement the Validator interface and be annotated with @Validator

Quick Start

Standardization

1. Create a class that implements com.thinkbiganalytics.policy.standardization.StandardizationPolicy
2. Add the @Standardizer annotation to the class
3. Annotate any field inputs with @PolicyProperty and any Constructor arguments with @PolicyPropertyRef

Validation

1. Create a class that implements com.thinkbiganalytics.policy.validation.ValidationPolicy
2. Add the @Validator annotation to the class
3. Annotate any field inputs with @PolicyProperty and any Constructor arguments with @PolicyPropertyRef

Annotations

@PolicyProperty - Field Annotation

Purpose: Annotate any Parameter that is needed to be captured the User Interface in order to create the Standardization or Validation Policy.

Attribute	Required	Default Value	Description
name	Y		Unique Name for the User Inerface and Domain to match. NOTE This will also become the User Interface Display Name, (displayName attribute) if one is not specified
displayName	N	name value above	The display name on the UI
value	N		default value on the UI
placeholder	N		Html Placeholder attribute
type	N	string	Render Types. Available Options (number, string, select, regex, date)
selectableValues	N		If type is select this is the Array of Strings that will be in the list Optionally use the property below for a label/value render
labelValues	N		If type is select this is the Array of Label/Values that will be in the list

@PolicyPropertyRef - Parameter Annotation

Purpose: Annotate any Constructor Parameter that references a given @PolicyProperty

Attribute	Required	Description
name	Y	This name should match the @PolicyProperty name

@Standardizer - Class Annotation

Purpose: Annotate the Class to inform the system and the User Interface that this is a Standardizer

Attribute	Required	Description
name	Y	This name of the Standardizer. This will be displayed on the User Interface
description	N	Short Description of the Standardizer. This will be displayed on the User Interface

@Validator - Class Annotation

Purpose: Annotate the Class to inform the system and the User Interface that this is a Validator

Attribute	Required	Description
name	Y	This name of the Validator. This will be displayed on the User Interface
description	N	Short Description of the Validator. This will be displayed on the User Interface

How To

Standardization

1. Create a new Java Class that implements the StandardizationPolicy class
2. Augment your Class with the @Standardizer annotation

@Standardizer(name = "Default Value", description = "Applies a default value if null")
public class DefaultValueStandardizer implements StandardizationPolicy, AcceptsEmptyValues {

    @Override
      public String convertValue(String value) {
        return StringUtils.defaultString(value, defaultStr);
      }

}

3. If fields are needed to be captured by the User interface annotate the fields with the @PolicyProperty annotation

@Standardizer(name = "Default Value", description = "Applies a default value if null")
public class DefaultValueStandardizer implements StandardizationPolicy, AcceptsEmptyValues {

 @PolicyProperty(name = "Default Value", hint = "If the value is null it will use this supplied value")
  private String defaultStr;
  
  ...
  }

4. Either supply a no arg Constructor, or supply a Constructor with the @PolicyPropertyRef indicating which property the parameter refers to.
   Note: The Name attribute of @PolicyPropertyRef matches on the name attribute of @PolicyProperty

@Standardizer(name = "Default Value", description = "Applies a default value if null")
public class DefaultValueStandardizer implements StandardizationPolicy, AcceptsEmptyValues {
    
  @PolicyProperty(name = "Default Value", hint = "If the value is null it will use this supplied value")
  private String defaultStr;


  public DefaultValueStandardizer(@PolicyPropertyRef(name = "Default Value") String defaultStr) {
    this.defaultStr = defaultStr;
  }
  
  @Override
    public String convertValue(String value) {
      return StringUtils.defaultString(value, defaultStr);
    }
}      

Note: If your StandardizationPolicy does not require inputs you can make it a Singelton class and the System will use the singelton if you implement a static method instance

@Standardizer(name = "Strip Non Numeric", description = "Remove any characters that are not numeric")
public class StripNonNumeric extends SimpleRegexReplacer {

  private static final StripNonNumeric instance = new StripNonNumeric();

  public static StripNonNumeric instance() {
    return instance;
  }

  private StripNonNumeric() {
    super("[^\\d.]", "");
  }

  @Override
  public String convertValue(String value) {
    return super.convertValue(value);
  }

  
}

Notice above the default constructor is private, but there is a static instance method.

Validation

To Be Documented.

Default Implementations

The Rest Controller

The field-policies-controller module discovers all classes on the classpath that have either a @Standardizer or @Validator and creates default User Interface Objects that are then displayed when a user creates a new Field Policy.

The com.thinkbiganalytics.policy.AvaliablePolicies class exposes these objects using Reflection. The com.thinkbiganalytics.policy.rest.controller.FieldPolicyRestController surfaces these so the User Interface can display the available options to the user.

Under the covers

In the field-policies-core module 2 classes are used to do the Standardization and Validation transformation

com.thinkbiganalytics.standardization.transform.StandardizationAnnotationTransformer;
com.thinkbiganalytics.standardization.transform.ValidatorAnnotationTransformer;

Additional Transformers are used that utilize these 2 classes to Transform multiple policies on a Field

com.thinkbiganalytics.policy.FieldPolicyTransfomer;
com.thinkbiganalytics.policy.FieldPoliciesJsonTransfomer;

The com.thinkbiganalytics.policy.FieldPoliciesJsonTransfomer is used by the spark-validate-cleanse module to convert a JSON string that has come from the User Interface and create Domain StandardizationPolicy and ValidationPolicy Objects.