feat: add join func

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

@@ -12,6 +12,7 @@ import com.jayway.jsonpath.internal.function.sequence.First;
 import com.jayway.jsonpath.internal.function.sequence.Index;
 import com.jayway.jsonpath.internal.function.sequence.Last;
 import com.jayway.jsonpath.internal.function.text.Concatenate;
+import com.jayway.jsonpath.internal.function.text.Join;
 import com.jayway.jsonpath.internal.function.text.Length;
 
 import java.util.Collections;
@@ -43,6 +44,7 @@ public class PathFunctionFactory {
 
         // Text Functions
         map.put("concat", Concatenate.class);
+        map.put("join", Join.class);
 
         // JSON Entity Functions
         map.put(Length.TOKEN_NAME, Length.class);

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

@@ -0,0 +1,166 @@
+package com.jayway.jsonpath.internal.function.text;
+
+import com.jayway.jsonpath.internal.EvaluationContext;
+import com.jayway.jsonpath.internal.PathRef;
+import com.jayway.jsonpath.internal.function.ParamType;
+import com.jayway.jsonpath.internal.function.Parameter;
+import com.jayway.jsonpath.internal.function.PathFunction;
+
+import java.util.*;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+
+/**
+ * join values in an array, supply two grammars:
+ * <p>
+ * 1. [].join([delimiter],[..path])
+ * 2. $.join([delimiter],[..path])
+ */
+public class Join implements PathFunction {
+    @Override
+    public Object invoke(String currentPath, PathRef parent, Object model, EvaluationContext ctx, List<Parameter> parameters) {
+        String delimiter = this.getDelimiterFromParameters(parameters);
+        Collection<String> results = Collections.emptyList();
+
+        // [].join([..path])
+        if (ctx.configuration().jsonProvider().isArray(model)) {
+            results = this.joinByArrayModel(model, ctx, parameters);
+        }
+
+        // $.join([delimiter],[..path])
+        if (null == results || results.size() == 0) {
+            results = this.joinByParams(ctx, parameters);
+        }
+
+        if (null == results || results.size() == 0) {
+            return "";
+        }
+        return String.join(delimiter, results);
+    }
+
+
+    /**
+     * get results by model
+     *
+     * @param model
+     * @param ctx
+     * @param parameters
+     * @return
+     */
+    protected Collection<String> joinByArrayModel(Object model, EvaluationContext ctx, List<Parameter> parameters) {
+        Collection<String> resultList = new ArrayList<>();
+        List<Parameter> pathParams = Optional.ofNullable(parameters).orElseGet(Collections::emptyList)
+                .stream().filter(item -> ParamType.PATH.equals(item.getType())).collect(Collectors.toList());
+
+        if (pathParams.size() == 0) {
+            return this.arrayIterableToList(ctx, model, item -> null);
+        }
+
+        for (Parameter pathParam : pathParams) {
+            List<String> list = this.arrayIterableToList(ctx, model, item -> {
+                Object value = pathParam.getPath().evaluate(item, model, ctx.configuration()).getValue();
+                return this.arrayIterableToList(ctx, value, obj -> null);
+            });
+            if (null == list || list.size() == 0) {
+                continue;
+            }
+            resultList.addAll(list);
+        }
+        return resultList;
+    }
+
+
+    /**
+     * get results by params
+     *
+     * @param ctx
+     * @param parameters
+     * @return
+     */
+    protected Collection<String> joinByParams(EvaluationContext ctx, List<Parameter> parameters) {
+        if (null == parameters || parameters.size() == 0) {
+            return null;
+        }
+        List<Parameter> notJsonParams = parameters.stream().filter(item -> ParamType.PATH.equals(item.getType())).collect(Collectors.toList());
+        if (notJsonParams.size() == 0) {
+            return parameters.stream().map(Parameter::getValue).filter(Objects::nonNull).map(Object::toString).collect(Collectors.toList());
+        }
+        List<String> list = Parameter.toList(String.class, ctx, notJsonParams);
+        return list.size() > 0 ? list : null;
+    }
+
+    /**
+     * get delimiter
+     *
+     * @param parameters
+     * @return
+     */
+    protected String getDelimiterFromParameters(List<Parameter> parameters) {
+        if (null != parameters && parameters.size() >= 1) {
+            Parameter parameter = parameters.get(0);
+            if (ParamType.JSON.equals(parameter.getType())) {
+                return parameter.getValue().toString();
+            }
+        }
+        return ",";
+    }
+
+
+    /**
+     * literal quantity type
+     *
+     * @param obj
+     * @return
+     */
+    protected boolean simpleType(Object obj) {
+        if (null == obj) {
+            return false;
+        }
+        return obj instanceof Number || obj instanceof CharSequence ||
+                obj instanceof Boolean || obj instanceof Character;
+    }
+
+
+    /**
+     * iterable
+     *
+     * @param ctx
+     * @param model
+     * @param itemIsNotSimpleFunc
+     */
+    protected List<String> arrayIterableToList(EvaluationContext ctx, Object model, Function<Object, List<String>> itemIsNotSimpleFunc) {
+        if (null == model) {
+            return Collections.emptyList();
+        }
+
+        if (this.simpleType(model)) {
+            return Collections.singletonList(model.toString());
+        }
+
+        boolean isArray = ctx.configuration().jsonProvider().isArray(model);
+        if (!isArray) {
+            return Collections.emptyList();
+        }
+
+        List<String> resultList = new ArrayList<>();
+        Iterable<?> iterable = ctx.configuration().jsonProvider().toIterable(model);
+        for (Object obj : iterable) {
+            if (null == obj) {
+                continue;
+            }
+
+            boolean isSimpleType = this.simpleType(obj);
+            if (isSimpleType) {
+                resultList.add(obj.toString());
+                continue;
+            }
+
+            List<String> items = itemIsNotSimpleFunc.apply(obj);
+            if (null == items || items.size() == 0) {
+                continue;
+            }
+            resultList.addAll(items);
+        }
+        return resultList;
+    }
+}

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

@@ -2,6 +2,7 @@ package com.jayway.jsonpath.internal.function;
 
 import com.jayway.jsonpath.Configuration;
 import com.jayway.jsonpath.Configurations;
+import com.jayway.jsonpath.Option;
 import net.minidev.json.JSONArray;
 import org.junit.Test;
 
@@ -106,4 +107,16 @@ public class JSONEntityPathFunctionTest extends BaseFunctionTest {
         verifyFunction(conf, path, BATCH_JSON, values);
     }
 
+
+
+    @Test
+    public void testParameterJoinFunctionCall() {
+        Configuration configuration = Configuration.builder().options(Option.DEFAULT_PATH_LEAF_TO_NULL, Option.SUPPRESS_EXCEPTIONS).build();
+        verifyFunction(configuration, "$.text.join()", TEXT_SERIES, "a,b,c,d,e,f");
+        verifyFunction(configuration, "$.text.join(\"|\")", TEXT_SERIES, "a|b|c|d|e|f");
+        verifyFunction(configuration, "$.join($.batches.results[*].productId)", BATCH_JSON, "23,23");
+        verifyFunction(configuration, "$.join(\" _ \",$.batches.results[*].values[?(@ > 10)])", BATCH_JSON, "45 _ 34 _ 23 _ 52 _ 12 _ 11 _ 18 _ 22");
+        verifyFunction(configuration, "$.join(\" \",$.batches.results[*].values[?(@ < 10)], $.batches.results[*].productId)", BATCH_JSON, "2 3 5 4 3 2 1 3 1 23 23");
+        verifyFunction(configuration, "$.batches.results.join(\" \", $.productId, $.values[?(@ < 10)])", BATCH_JSON, "23 23 2 3 5 4 3 2 1 3 1");
+    }
 }