Defines the pattern for taking unique items from collection of JSONArray

Author: PavelSakharchuk

README.md

@@ -85,20 +85,21 @@ Functions
 Functions can be invoked at the tail end of a path - the input to a function is the output of the path expression.
 The function output is dictated by the function itself.
 
-| Function  | Description                                                                          | Output type          |
-|:----------|:-------------------------------------------------------------------------------------|:---------------------|
-| min()     | Provides the min value of an array of numbers                                        | Double               |
-| max()     | Provides the max value of an array of numbers                                        | Double               |
-| avg()     | Provides the average value of an array of numbers                                    | Double               | 
-| stddev()  | Provides the standard deviation value of an array of numbers                         | Double               | 
-| length()  | Provides the length of an array                                                      | Integer              |
-| sum()     | Provides the sum value of an array of numbers                                        | Double               |
-| keys()    | Provides the property keys (An alternative for terminal tilde `~`)                   | `Set<E>`             |
-| concat(X) | Provides a concatinated version of the path output with a new item                   | like input           |
-| append(X) | add an item to the json path output array                                            | like input           |
-| first()   | Provides the first item of an array                                                  | Depends on the array |
-| last()    | Provides the last item of an array                                                   | Depends on the array |
-| index(X)  | Provides the item of an array of index: X, if the X is negative, take from backwards | Depends on the array |
+| Function   | Description                                                                          | Output type          |
+|:-----------|:-------------------------------------------------------------------------------------|:---------------------|
+| min()      | Provides the min value of an array of numbers                                        | Double               |
+| max()      | Provides the max value of an array of numbers                                        | Double               |
+| avg()      | Provides the average value of an array of numbers                                    | Double               | 
+| stddev()   | Provides the standard deviation value of an array of numbers                         | Double               | 
+| length()   | Provides the length of an array                                                      | Integer              |
+| sum()      | Provides the sum value of an array of numbers                                        | Double               |
+| keys()     | Provides the property keys (An alternative for terminal tilde `~`)                   | `Set<E>`             |
+| concat(X)  | Provides a concatinated version of the path output with a new item                   | like input           |
+| append(X)  | add an item to the json path output array                                            | like input           |
+| first()    | Provides the first item of an array                                                  | Depends on the array |
+| last()     | Provides the last item of an array                                                   | Depends on the array |
+| index(X)   | Provides the item of an array of index: X, if the X is negative, take from backwards | Depends on the array |
+| distinct() | Provides the unique items of an array                                                | Depends on the array |
 Filter Operators
 -----------------
 

json-path/src/main/java/com/jayway/jsonpath/internal/function/PathFunctionFactory.java

@@ -8,6 +8,7 @@
 import com.jayway.jsonpath.internal.function.numeric.Min;
 import com.jayway.jsonpath.internal.function.numeric.StandardDeviation;
 import com.jayway.jsonpath.internal.function.numeric.Sum;
+import com.jayway.jsonpath.internal.function.sequence.Distinct;
 import com.jayway.jsonpath.internal.function.sequence.First;
 import com.jayway.jsonpath.internal.function.sequence.Index;
 import com.jayway.jsonpath.internal.function.sequence.Last;
@@ -53,6 +54,7 @@ public class PathFunctionFactory {
         // Sequential Functions
         map.put("first", First.class);
         map.put("last", Last.class);
+        map.put("distinct", Distinct.class);
         map.put("index", Index.class);
 
 

json-path/src/main/java/com/jayway/jsonpath/internal/function/sequence/Distinct.java

@@ -0,0 +1,31 @@
+package com.jayway.jsonpath.internal.function.sequence;
+
+import com.jayway.jsonpath.JsonPathException;
+import com.jayway.jsonpath.internal.EvaluationContext;
+import com.jayway.jsonpath.internal.PathRef;
+import com.jayway.jsonpath.internal.function.Parameter;
+import com.jayway.jsonpath.internal.function.PathFunction;
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+
+/**
+ * Take the unique items from collection of JSONArray
+ *
+ * Created by PavelSakharchuk on 21/09/23
+ */
+public class Distinct implements PathFunction {
+
+    @Override
+    public Object invoke(String currentPath, PathRef parent, Object model, EvaluationContext ctx, List<Parameter> parameters) {
+        if(ctx.configuration().jsonProvider().isArray(model)){
+            Iterable<?> objects = ctx.configuration().jsonProvider().toIterable(model);
+            Set<Object> objectSet = new HashSet<>();
+            objects.forEach(objectSet::add);
+
+            return  new ArrayList<>(objectSet);
+        }
+        throw new JsonPathException("Aggregation function attempted to calculate value using empty array");
+    }
+}

json-path/src/test/java/com/jayway/jsonpath/internal/function/BaseFunctionTest.java

@@ -13,7 +13,7 @@
  */
 public class BaseFunctionTest {
     protected static final String NUMBER_SERIES = "{\"empty\": [], \"numbers\" : [ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]}";
-    protected static final String TEXT_SERIES = "{\"urls\": [\"http://api.worldbank.org/countries/all/?format=json\", \"http://api.worldbank.org/countries/all/?format=json\"], \"text\" : [ \"a\", \"b\", \"c\", \"d\", \"e\", \"f\" ]}";
+    protected static final String TEXT_SERIES = "{\"urls\": [\"http://api.worldbank.org/countries/all/?format=json\", \"http://api.worldbank.org/countries/all/?format=json\"], \"text\" : [ \"a\", \"b\", \"c\", \"d\", \"d\", \"e\", \"f\" ]}";
     protected static final String TEXT_AND_NUMBER_SERIES = "{\"text\" : [ \"a\", \"b\", \"c\", \"d\", \"e\", \"f\" ], \"numbers\" : [ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]}";
 
     /**

json-path/src/test/java/com/jayway/jsonpath/internal/function/SequentialPathFunctionTest.java

@@ -2,6 +2,7 @@
 
 import com.jayway.jsonpath.Configuration;
 import com.jayway.jsonpath.Configurations;
+import java.util.Arrays;
 import org.junit.Test;
 
 /**
@@ -10,6 +11,7 @@
  * -first
  * -last
  * -index(X)
+ * -distinct
  *
  * Created by git9527 on 6/11/22.
  */
@@ -50,4 +52,9 @@ public void testIndexOfText() throws Exception {
         verifyFunction(conf, "$.text.index(-1)", TEXT_SERIES, "f");
         verifyFunction(conf, "$.text.index(1)", TEXT_SERIES, "b");
     }
+
+    @Test
+    public void testDistinctOfText() throws Exception {
+        verifyFunction(conf, "$.text.distinct()", TEXT_SERIES, Arrays.asList("a", "b", "c", "d", "e", "f"));
+    }
 }