feat: max_by and min_by function

Author: dreamorosi

packages/jmespath/src/functions/Functions.ts

@@ -183,6 +183,58 @@ class Functions {
     }
   }
 
+  /**
+   * Get the item in the provided array that has the maximum value when the provided expression is evaluated.
+   *
+   * @param args The array of items to get the maximum value of
+   * @param expression The expression to evaluate for each item in the array
+   * @returns The item in the array that has the maximum value when the expression is evaluated
+   */
+  @Functions.signature({
+    argumentsSpecs: [['array'], ['expression']],
+  })
+  public funcMaxBy(
+    args: Array<JSONObject>,
+    expression: Expression
+  ): JSONObject | null {
+    if (args.length === 0) {
+      return null;
+    }
+
+    const visitedArgs = args.map((arg) => ({
+      arg,
+      visited: expression.visit(arg),
+    }));
+
+    const max = visitedArgs.reduce((max, current) => {
+      const type = getType(current.visited);
+      if (type !== 'string' && type !== 'number') {
+        throw new JMESPathTypeError({
+          currentValue: current.visited,
+          expectedTypes: ['string'],
+          actualType: type,
+        });
+      }
+
+      if (
+        (max.visited === null || max.visited === undefined) &&
+        (current.visited === null || current.visited === undefined)
+      ) {
+        return max;
+      } else if (max.visited === null || max.visited === undefined) {
+        return current;
+      } else if (current.visited === null || current.visited === undefined) {
+        return max;
+      } else if (max.visited === current.visited) {
+        return max;
+      } else {
+        return max.visited > current.visited ? max : current;
+      }
+    }, visitedArgs[0]);
+
+    return max.arg;
+  }
+
   /**
    * Merge the provided objects into a single object.
    *
@@ -219,6 +271,58 @@ class Functions {
     }
   }
 
+  /**
+   * Get the item in the provided array that has the minimum value when the provided expression is evaluated.
+   *
+   * @param args The array of items to get the minimum value of
+   * @param expression The expression to evaluate for each item in the array
+   * @returns The item in the array that has the minimum value when the expression is evaluated
+   */
+  @Functions.signature({
+    argumentsSpecs: [['array'], ['expression']],
+  })
+  public funcMinBy(
+    args: Array<JSONObject>,
+    expression: Expression
+  ): JSONObject | null {
+    if (args.length === 0) {
+      return null;
+    }
+
+    const visitedArgs = args.map((arg) => ({
+      arg,
+      visited: expression.visit(arg),
+    }));
+
+    const min = visitedArgs.reduce((min, current) => {
+      const type = getType(current.visited);
+      if (type !== 'string' && type !== 'number') {
+        throw new JMESPathTypeError({
+          currentValue: current.visited,
+          expectedTypes: ['string'],
+          actualType: type,
+        });
+      }
+
+      if (
+        (min.visited === null || min.visited === undefined) &&
+        (current.visited === null || current.visited === undefined)
+      ) {
+        return min;
+      } else if (min.visited === null || min.visited === undefined) {
+        return current;
+      } else if (current.visited === null || current.visited === undefined) {
+        return min;
+      } else if (min.visited === current.visited) {
+        return min;
+      } else {
+        return min.visited < current.visited ? min : current;
+      }
+    }, visitedArgs[0]);
+
+    return min.arg;
+  }
+
   /**
    * Get the first argument that does not evaluate to null.
    * If all arguments evaluate to null, then null is returned.

packages/jmespath/tests/unit/functions.test.ts

@@ -1849,7 +1849,7 @@ describe('Functions tests', () => {
     expect(() => search(expression, data)).toThrow(error);
   });
 
-  /* it.each([
+  it.each([
     {
       expression: 'max_by(people, &age)',
       expected: {
@@ -1921,18 +1921,20 @@ describe('Functions tests', () => {
 
     // Assess
     expect(result).toStrictEqual(expected);
-  }); */
-  /* it.each([
+  });
+
+  it.each([
     {
       expression: 'max_by(people, &bool)',
-      error: 'TypeError: expected one of (number | string), received boolean',
+      error:
+        'Invalid argument type for function max_by(), expected "string" but found "boolean" in expression: max_by(people, &bool)',
     },
     {
       expression: 'max_by(people, &extra)',
-      error: 'TypeError: expected one of (number | string), received null',
+      error:
+        'Invalid argument type for function max_by(), expected "string" but found "null" in expression: max_by(people, &extra)',
     },
   ])('max_by() function special cases errors', ({ expression, error }) => {
-    // TODO: see if we can assert the error type as well in max_by() function special cases errors tests
     // Prepare
     const data = {
       people: [
@@ -1973,8 +1975,9 @@ describe('Functions tests', () => {
 
     // Act & Assess
     expect(() => search(expression, data)).toThrow(error);
-  }); */
-  /* it.each([
+  });
+
+  it.each([
     {
       expression: 'min_by(people, &age)',
       expected: {
@@ -2046,18 +2049,20 @@ describe('Functions tests', () => {
 
     // Assess
     expect(result).toStrictEqual(expected);
-  }); */
-  /* it.each([
+  });
+
+  it.each([
     {
       expression: 'min_by(people, &bool)',
-      error: 'TypeError: expected one of (number | string), received boolean',
+      error:
+        'Invalid argument type for function min_by(), expected "string" but found "boolean" in expression: min_by(people, &bool)',
     },
     {
       expression: 'min_by(people, &extra)',
-      error: 'TypeError: expected one of (number | string), received null',
+      error:
+        'Invalid argument type for function min_by(), expected "string" but found "null" in expression: min_by(people, &extra)',
     },
   ])('min_by() function special cases errors', ({ expression, error }) => {
-    // TODO: see if we can assert the error type as well in min_by() function special cases errors tests
     // Prepare
     const data = {
       people: [
@@ -2099,7 +2104,7 @@ describe('Functions tests', () => {
     // Act & Assess
     expect(() => search(expression, data)).toThrow(error);
   });
- */
+
   it.each([
     {
       description: 'stable sort order',