Add a ProviderValidators for custom the behaviour of Custom Validators dynamically

Author: GiskardB

README.md

@@ -430,6 +430,84 @@ Schema schema = schemaLoader.load().build(); // the schema is created using the
 schema.validate(jsonDocument);  // the document validation happens here
 ```
 
+### Custom Provider Validators
+The library use `DefaultProviderValidators` that collects all the validators used in the process of validation of json.
+To use a custom Provider of Validators basically you:
+
+ * create your own ProviderValidators in a class implementing the `org.everit.json.schema.loader.ProviderValidators` interface
+ * bind your ProviderValidators in a `org.everit.json.schema.loader.SchemaLoader.SchemaLoaderBuilder.builder(IstanceOfNewProviderValidators` instance before loading the actual schema
+
+#### Example for validate a field with a function javascript
+
+Assume a schema with a simple function of validation that return true if the subject is equals to number 5:
+```java
+....
+  "age": {
+    ...
+    "format": "javascript: subject == 5"
+  },
+...
+```
+
+Let's create a custom ProviderValidators that catch the intent of launch a javascript function and istantiate a new custom validator
+```java
+class ExampleDefaultProviderValidators extends DefaultProviderValidators {
+    @Override
+    public FormatValidator getFormatValidator(String formatName) {
+
+        if (!this.getFormatValidators().containsKey(formatName)
+                && formatName.startsWith("javascript:")) {
+            String script = formatName.substring(formatName.lastIndexOf("javascript:"),formatName.length());
+            this.addFormatValidator(formatName, new JavascriptFormatValidator(formatName, script));
+        }
+        return super.getFormatValidator(formatName);
+    }
+}
+
+class JavascriptFormatValidator implements FormatValidator {
+
+    String script;
+    String formatName;
+
+    public JavascriptFormatValidator(String formatName, String script) {
+        this.formatName = formatName;
+        this.script = script;
+    }
+
+    @Override
+    public Optional<String> validate(String subject) {
+
+        ScriptEngine javaScriptEngine = new ScriptEngineManager().getEngineByName("js");
+        javaScriptEngine.put("subject",subject);
+        try {
+            Boolean result = (Boolean) javaScriptEngine.eval(script);
+            if (!result) {
+                return Optional.of(String.format("the length of string [%s] is greater than 5", subject));
+            }
+        } catch (ScriptException e) {
+            e.printStackTrace();
+            return Optional.of(String.format("Error on evalutation of [%s] ", subject));
+        }
+        return Optional.empty();
+    }
+
+    @Override
+    public String formatName() {
+        return formatName;
+    }
+}
+```
+
+In the builder we can set this new ProviderValidators and launch the validation process.
+```java
+ExampleDefaultProviderValidators customProviderValidators = new ExampleDefaultProviderValidators();
+SchemaLoader schemaLoader = SchemaLoader.builder(customProviderValidators)
+	.......
+	.build();
+Schema schema = schemaLoader.load().build(); // the schema is created using the above created configuration
+schema.validate(jsonDocument);  // the document validation happens here
+```
+
 
 ## $ref resolution
 

core/src/main/java/org/everit/json/schema/loader/LoaderConfig.java

@@ -11,6 +11,7 @@
 import java.util.Map;
 
 import org.everit.json.schema.FormatValidator;
+import org.everit.json.schema.loader.internal.DefaultProviderValidators;
 import org.everit.json.schema.loader.internal.DefaultSchemaClient;
 import org.everit.json.schema.regexp.JavaUtilRegexpFactory;
 import org.everit.json.schema.regexp.RegexpFactory;
@@ -21,12 +22,13 @@
 class LoaderConfig {
 
     static LoaderConfig defaultV4Config() {
-        return new LoaderConfig(new DefaultSchemaClient(), DRAFT_4.defaultFormatValidators(), DRAFT_4, false);
+        return new LoaderConfig(new DefaultSchemaClient(), new DefaultProviderValidators(DRAFT_4.defaultFormatValidators()), DRAFT_4, false);
     }
 
     final SchemaClient schemaClient;
 
-    final Map<String, FormatValidator> formatValidators;
+    //final Map<String, FormatValidator> formatValidators;
+    final ProviderValidators providerValidators;
 
     final Map<URI, Object> schemasByURI;
 
@@ -38,17 +40,17 @@ static LoaderConfig defaultV4Config() {
 
     final RegexpFactory regexpFactory;
 
-    LoaderConfig(SchemaClient schemaClient, Map<String, FormatValidator> formatValidators,
+    LoaderConfig(SchemaClient schemaClient, ProviderValidators providerValidators,
             SpecificationVersion specVersion, boolean useDefaults) {
-        this(schemaClient, formatValidators, emptyMap(), specVersion, useDefaults, false, new JavaUtilRegexpFactory());
+        this(schemaClient, providerValidators, emptyMap(), specVersion, useDefaults, false, new JavaUtilRegexpFactory());
     }
 
-    LoaderConfig(SchemaClient schemaClient, Map<String, FormatValidator> formatValidators,
+    LoaderConfig(SchemaClient schemaClient, ProviderValidators providerValidators,
             Map<URI, Object> schemasByURI,
             SpecificationVersion specVersion, boolean useDefaults, boolean nullableSupport,
             RegexpFactory regexpFactory) {
         this.schemaClient = requireNonNull(schemaClient, "schemaClient cannot be null");
-        this.formatValidators = requireNonNull(formatValidators, "formatValidators cannot be null");
+        this.providerValidators = requireNonNull(providerValidators, "providerValidators cannot be null");
         if (schemasByURI == null) {
             this.schemasByURI = new HashMap<>();
         } else {
@@ -71,7 +73,7 @@ SchemaLoader.SchemaLoaderBuilder initLoader() {
                 .useDefaults(this.useDefaults)
                 .regexpFactory(this.regexpFactory)
                 .nullableSupport(this.nullableSupport)
-                .formatValidators(new HashMap<>(this.formatValidators));
+                .formatValidators(new HashMap<>(this.providerValidators.getFormatValidators()));
         loaderBuilder.schemasByURI = schemasByURI;
         if (DRAFT_6.equals(specVersion)) {
             loaderBuilder.draftV6Support();

core/src/main/java/org/everit/json/schema/loader/ProviderValidators.java

@@ -0,0 +1,56 @@
+package org.everit.json.schema.loader;
+
+import org.everit.json.schema.FormatValidator;
+import java.util.Map;
+
+/**
+ * Interface for the provider of validators used in Schema
+ */
+public interface ProviderValidators {
+
+    /**
+     * Return a FormatValidator with a name
+     *
+     * @param formatName Name of the FormatValidator
+     * @return
+     */
+    FormatValidator getFormatValidator(String formatName);
+
+    /**
+     * Add a FormatValidator with a name
+     *
+     * @param formatName  Name of the FormatValidator
+     * @param formatValidator The FormatValidator to add
+     */
+    void addFormatValidator(String formatName, FormatValidator formatValidator);
+
+    /**
+     * Add a FormatValidator with a name if is or is not present
+     *
+     * @param formatName  Name of the FormatValidator
+     * @param formatValidator The FormatValidator to add
+     * @param addIfAbsent If true, the FormatValidator can add on map
+     */
+    void addFormatValidator(String formatName, FormatValidator formatValidator, boolean addIfAbsent);
+
+    /**
+     * Add a map of FormatValidator to the base map
+     *
+     * @param formatValidators All the FormatValidator to add on a base map
+     */
+    void addAllFormatValidators(Map<String, FormatValidator> formatValidators);
+
+    /**
+     * Initialize the map of FormatValidator
+     *
+     * @param formatValidators the map of FormatValidator
+     */
+    void initAllFormatValidators(Map<String, FormatValidator> formatValidators);
+
+    /**
+     * Return all the validators
+     *
+     * @return The map of all Validators
+     */
+    Map<String, FormatValidator> getFormatValidators();
+}

core/src/main/java/org/everit/json/schema/loader/SchemaExtractor.java

@@ -156,7 +156,7 @@ NumberSchema.Builder buildNumberSchema() {
 
     StringSchema.Builder buildStringSchema() {
         PropertySnifferSchemaExtractor.STRING_SCHEMA_PROPS.forEach(consumedKeys::keyConsumed);
-        return new StringSchemaLoader(schemaJson.ls, config().formatValidators).load();
+        return new StringSchemaLoader(schemaJson.ls, config().providerValidators).load();
     }
 
     abstract List<Schema.Builder<?>> extract();

core/src/main/java/org/everit/json/schema/loader/SchemaLoader.java

@@ -27,6 +27,7 @@
 import org.everit.json.schema.SchemaException;
 import org.everit.json.schema.SchemaLocation;
 import org.everit.json.schema.TrueSchema;
+import org.everit.json.schema.loader.internal.DefaultProviderValidators;
 import org.everit.json.schema.loader.internal.DefaultSchemaClient;
 import org.everit.json.schema.loader.internal.WrappingFormatValidator;
 import org.everit.json.schema.regexp.JavaUtilRegexpFactory;
@@ -61,7 +62,8 @@ public static class SchemaLoaderBuilder {
 
         SchemaLocation pointerToCurrentObj = SchemaLocation.empty();
 
-        Map<String, FormatValidator> formatValidators = new HashMap<>();
+        //Map<String, FormatValidator> formatValidators = new HashMap<>();
+        ProviderValidators providerValidators = new DefaultProviderValidators();
 
         SpecificationVersion specVersion;
 
@@ -81,6 +83,11 @@ public SchemaLoaderBuilder() {
             setSpecVersion(DRAFT_4);
         }
 
+        public SchemaLoaderBuilder(final ProviderValidators providerValidators) {
+            setSpecVersion(DRAFT_4);
+            this.providerValidators = providerValidators;
+        }
+
         /**
          * Registers a format validator with the name returned by {@link FormatValidator#formatName()}.
          *
@@ -89,7 +96,7 @@ public SchemaLoaderBuilder() {
          * @return {@code this}
          */
         public SchemaLoaderBuilder addFormatValidator(FormatValidator formatValidator) {
-            formatValidators.put(formatValidator.formatName(), formatValidator);
+            providerValidators.addFormatValidator(formatValidator.formatName(), formatValidator);
             return this;
         }
 
@@ -106,9 +113,9 @@ public SchemaLoaderBuilder addFormatValidator(FormatValidator formatValidator) {
         public SchemaLoaderBuilder addFormatValidator(String formatName,
                 final FormatValidator formatValidator) {
             if (!Objects.equals(formatName, formatValidator.formatName())) {
-                formatValidators.put(formatName, new WrappingFormatValidator(formatName, formatValidator));
+                providerValidators.addFormatValidator(formatName, new WrappingFormatValidator(formatName, formatValidator));
             } else {
-                formatValidators.put(formatName, formatValidator);
+                providerValidators.addFormatValidator(formatName, formatValidator);
             }
             return this;
         }
@@ -154,10 +161,10 @@ private void addBuiltInFormatValidators() {
 
             if (enableOverrideOfBuiltInFormatValidators) {
                 for (Entry<String, FormatValidator> entry : defaultFormatValidators.entrySet()) {
-                    formatValidators.putIfAbsent(entry.getKey(), entry.getValue());
+                    providerValidators.addFormatValidator(entry.getKey(), entry.getValue(), true);
                 }
             } else {
-                formatValidators.putAll(defaultFormatValidators);
+                providerValidators.addAllFormatValidators(defaultFormatValidators);
             }
         }
         @Deprecated
@@ -229,7 +236,7 @@ public SchemaLoaderBuilder schemaJson(Object schema) {
         }
 
         SchemaLoaderBuilder formatValidators(Map<String, FormatValidator> formatValidators) {
-            this.formatValidators = formatValidators;
+            this.providerValidators.initAllFormatValidators(formatValidators);
             return this;
         }
 
@@ -279,6 +286,10 @@ public static SchemaLoaderBuilder builder() {
         return new SchemaLoaderBuilder();
     }
 
+    public static SchemaLoaderBuilder builder(ProviderValidators providerValidators) {
+        return new SchemaLoaderBuilder(providerValidators);
+    }
+
     /**
      * Loads a JSON schema to a schema validator using a {@link DefaultSchemaClient default HTTP
      * client}.
@@ -342,7 +353,8 @@ public SchemaLoader(SchemaLoaderBuilder builder) {
             specVersion = builder.specVersion;
         }
         this.config = new LoaderConfig(builder.schemaClient,
-                builder.formatValidators,
+                //builder.formatValidators,
+                builder.providerValidators,
                 builder.schemasByURI,
                 specVersion,
                 builder.useDefaults,
@@ -477,7 +489,7 @@ SpecificationVersion specVersion() {
      */
     @Deprecated
     Optional<FormatValidator> getFormatValidator(String formatName) {
-        return Optional.ofNullable(config.formatValidators.get(formatName));
+        return Optional.ofNullable(config.providerValidators.getFormatValidator(formatName));
     }
 
 }

core/src/main/java/org/everit/json/schema/loader/StringSchemaLoader.java

@@ -8,6 +8,7 @@
 
 import org.everit.json.schema.FormatValidator;
 import org.everit.json.schema.StringSchema;
+import org.everit.json.schema.loader.internal.DefaultProviderValidators;
 
 /**
  * @author erosb
@@ -16,21 +17,22 @@ public class StringSchemaLoader {
 
     private LoadingState ls;
 
-    private Map<String, FormatValidator> formatValidators;
+    //private Map<String, FormatValidator> formatValidators;
+    private ProviderValidators providerValidators;
 
     /**
      * Creates an instance with {@link SpecificationVersion#defaultFormatValidators()}  draft v4 format validators}.
      *
-     * @deprecated explicitly specify the format validators with {@link #StringSchemaLoader(LoadingState, Map)} instead
+     * @deprecated explicitly specify the format validators with {@link #StringSchemaLoader(LoadingState, ProviderValidators)} instead
      */
     @Deprecated
     public StringSchemaLoader(LoadingState ls) {
-        this(ls, DRAFT_4.defaultFormatValidators());
+        this(ls, new DefaultProviderValidators(DRAFT_4.defaultFormatValidators()));
     }
 
-    StringSchemaLoader(LoadingState ls, Map<String, FormatValidator> formatValidators) {
+    StringSchemaLoader(LoadingState ls, ProviderValidators providerValidators) {
         this.ls = requireNonNull(ls, "ls cannot be null");
-        this.formatValidators = unmodifiableMap(requireNonNull(formatValidators, "formatValidators cannot be null"));
+        this.providerValidators = requireNonNull(providerValidators, "providerValidators cannot be null");
     }
 
     public StringSchema.Builder load() {
@@ -46,7 +48,7 @@ public StringSchema.Builder load() {
     }
 
     private void addFormatValidator(StringSchema.Builder builder, String formatName) {
-        FormatValidator formatValidator = formatValidators.get(formatName);
+        FormatValidator formatValidator = providerValidators.getFormatValidator(formatName);
         if (formatValidator != null) {
             builder.formatValidator(formatValidator);
         }