Make Link and NavLink components accept "to" property as a function

packages/react-router-dom/.size-snapshot.json

@@ -1,26 +1,26 @@
 {
   "esm/react-router-dom.js": {
-    "bundled": 8362,
-    "minified": 5058,
-    "gzipped": 1651,
+    "bundled": 8874,
+    "minified": 5312,
+    "gzipped": 1711,
     "treeshaked": {
       "rollup": {
-        "code": 453,
+        "code": 508,
         "import_statements": 417
       },
       "webpack": {
-        "code": 1661
+        "code": 1800
       }
     }
   },
   "umd/react-router-dom.js": {
-    "bundled": 159395,
-    "minified": 56787,
-    "gzipped": 16387
+    "bundled": 159933,
+    "minified": 56923,
+    "gzipped": 16433
   },
   "umd/react-router-dom.min.js": {
-    "bundled": 96151,
-    "minified": 33747,
-    "gzipped": 9951
+    "bundled": 96671,
+    "minified": 33875,
+    "gzipped": 9980
   }
 }

packages/react-router-dom/docs/api/Link.md

@@ -36,6 +36,18 @@ An object that can have any of the following properties:
 />
 ```
 
+## to: function
+
+A function to which current location is passed as an argument and which should return location representation as a string or as an object
+
+```jsx
+<Link to={location => ({ ...location, pathname: "/courses" })} />
+```
+
+```jsx
+<Link to={location => `${location.pathname}?sort=name`} />
+```
+
 ## replace: bool
 
 When `true`, clicking the link will replace the current entry in the history stack instead of adding a new one.

packages/react-router-dom/modules/Link.js

@@ -1,8 +1,8 @@
 import React from "react";
 import { __RouterContext as RouterContext } from "react-router";
-import { createLocation } from "history";
 import PropTypes from "prop-types";
 import invariant from "tiny-invariant";
+import { resolveToLocation, normalizeToLocation } from "./utils/locationUtils";
 
 function isModifiedEvent(event) {
   return !!(event.metaKey || event.altKey || event.ctrlKey || event.shiftKey);
@@ -12,7 +12,7 @@ function isModifiedEvent(event) {
  * The public API for rendering a history-aware <a>.
  */
 class Link extends React.Component {
-  handleClick(event, history) {
+  handleClick(event, context) {
     try {
       if (this.props.onClick) this.props.onClick(event);
     } catch (ex) {
@@ -28,9 +28,13 @@ class Link extends React.Component {
     ) {
       event.preventDefault();
 
-      const method = this.props.replace ? history.replace : history.push;
+      const location = resolveToLocation(this.props.to, context.location);
 
-      method(this.props.to);
+      const method = this.props.replace
+        ? context.history.replace
+        : context.history.push;
+
+      method(location);
     }
   }
 
@@ -42,16 +46,17 @@ class Link extends React.Component {
         {context => {
           invariant(context, "You should not use <Link> outside a <Router>");
 
-          const location =
-            typeof to === "string"
-              ? createLocation(to, null, null, context.location)
-              : to;
+          const location = normalizeToLocation(
+            resolveToLocation(to, context.location),
+            context.location
+          );
+
           const href = location ? context.history.createHref(location) : "";
 
           return (
             <a
               {...rest}
-              onClick={event => this.handleClick(event, context.history)}
+              onClick={event => this.handleClick(event, context)}
               href={href}
               ref={innerRef}
             />
@@ -63,7 +68,11 @@ class Link extends React.Component {
 }
 
 if (__DEV__) {
-  const toType = PropTypes.oneOfType([PropTypes.string, PropTypes.object]);
+  const toType = PropTypes.oneOfType([
+    PropTypes.string,
+    PropTypes.object,
+    PropTypes.func
+  ]);
   const innerRefType = PropTypes.oneOfType([
     PropTypes.string,
     PropTypes.func,

packages/react-router-dom/modules/NavLink.js

@@ -1,8 +1,9 @@
 import React from "react";
 import { __RouterContext as RouterContext, matchPath } from "react-router";
 import PropTypes from "prop-types";
-import Link from "./Link";
 import invariant from "tiny-invariant";
+import Link from "./Link";
+import { resolveToLocation, normalizeToLocation } from "./utils/locationUtils";
 
 function joinClassnames(...classnames) {
   return classnames.filter(i => i).join(" ");
@@ -24,19 +25,22 @@ function NavLink({
   to,
   ...rest
 }) {
-  const path = typeof to === "object" ? to.pathname : to;
-
-  // Regex taken from: https://github.com/pillarjs/path-to-regexp/blob/master/index.js#L202
-  const escapedPath = path && path.replace(/([.+*?=^!:${}()[\]|/\\])/g, "\\$1");
-
   return (
     <RouterContext.Consumer>
       {context => {
         invariant(context, "You should not use <NavLink> outside a <Router>");
 
-        const pathToMatch = locationProp
-          ? locationProp.pathname
-          : context.location.pathname;
+        const currentLocation = locationProp || context.location;
+        const { pathname: pathToMatch } = currentLocation;
+        const toLocation = normalizeToLocation(
+          resolveToLocation(to, currentLocation),
+          currentLocation
+        );
+        const { pathname: path } = toLocation;
+        // Regex taken from: https://github.com/pillarjs/path-to-regexp/blob/master/index.js#L202
+        const escapedPath =
+          path && path.replace(/([.+*?=^!:${}()[\]|/\\])/g, "\\$1");
+
         const match = escapedPath
           ? matchPath(pathToMatch, { path: escapedPath, exact, strict })
           : null;
@@ -54,7 +58,7 @@ function NavLink({
             aria-current={(isActive && ariaCurrent) || null}
             className={className}
             style={style}
-            to={to}
+            to={toLocation}
             {...rest}
           />
         );

packages/react-router-dom/modules/__tests__/Link-test.js

@@ -75,6 +75,34 @@ describe("A <Link>", () => {
     expect(a.getAttribute("href")).toEqual("/the/path?the=query#the-hash");
   });
 
+  it("accepts an object returning function `to` prop", () => {
+    const to = location => ({ ...location, search: "foo=bar" });
+
+    renderStrict(
+      <MemoryRouter initialEntries={["/hello"]}>
+        <Link to={to}>link</Link>
+      </MemoryRouter>,
+      node
+    );
+
+    const a = node.querySelector("a");
+    expect(a.getAttribute("href")).toEqual("/hello?foo=bar");
+  });
+
+  it("accepts a string returning function `to` prop", () => {
+    const to = location => `${location.pathname}?foo=bar`;
+
+    ReactDOM.render(
+      <MemoryRouter initialEntries={["/hello"]}>
+        <Link to={to}>link</Link>
+      </MemoryRouter>,
+      node
+    );
+
+    const a = node.querySelector("a");
+    expect(a.getAttribute("href")).toEqual("/hello?foo=bar");
+  });
+
   describe("with no pathname", () => {
     it("resolves using the current location", () => {
       renderStrict(
@@ -218,6 +246,42 @@ describe("A <Link>", () => {
       expect(memoryHistory.push).toBeCalledWith(to);
     });
 
+    it("calls onClick eventhandler and history.push with function `to` prop", () => {
+      const memoryHistoryFoo = createMemoryHistory({
+        initialEntries: ["/foo"]
+      });
+      memoryHistoryFoo.push = jest.fn();
+      const clickHandler = jest.fn();
+      let to = null;
+      const toFn = location => {
+        to = {
+          ...location,
+          pathname: "hello",
+          search: "world"
+        };
+        return to;
+      };
+
+      renderStrict(
+        <Router history={memoryHistoryFoo}>
+          <Link to={toFn} onClick={clickHandler}>
+            link
+          </Link>
+        </Router>,
+        node
+      );
+
+      const a = node.querySelector("a");
+      ReactTestUtils.Simulate.click(a, {
+        defaultPrevented: false,
+        button: 0
+      });
+
+      expect(clickHandler).toBeCalledTimes(1);
+      expect(memoryHistoryFoo.push).toBeCalledTimes(1);
+      expect(memoryHistoryFoo.push).toBeCalledWith(to);
+    });
+
     it("does not call history.push on right click", () => {
       const to = "/the/path?the=query#the-hash";
 

packages/react-router-dom/modules/__tests__/NavLink-test.js

@@ -25,6 +25,21 @@ describe("A <NavLink>", () => {
       expect(a.className).toContain("active");
     });
 
+    it("applies its default activeClassName with function `to` prop", () => {
+      renderStrict(
+        <MemoryRouter initialEntries={["/pizza"]}>
+          <NavLink to={location => ({ ...location, pathname: "/pizza" })}>
+            Pizza!
+          </NavLink>
+        </MemoryRouter>,
+        node
+      );
+
+      const a = node.querySelector("a");
+
+      expect(a.className).toContain("active");
+    });
+
     it("applies a custom activeClassName instead of the default", () => {
       renderStrict(
         <MemoryRouter initialEntries={["/pizza"]}>
@@ -472,6 +487,25 @@ describe("A <NavLink>", () => {
       expect(a.className).toContain("active");
     });
 
+    it("is passed as an argument to function `to` prop", () => {
+      renderStrict(
+        <MemoryRouter initialEntries={["/pizza"]}>
+          <NavLink
+            to={location => location}
+            activeClassName="selected"
+            location={{ pathname: "/pasta" }}
+          >
+            Pasta!
+          </NavLink>
+        </MemoryRouter>,
+        node
+      );
+
+      const a = node.querySelector("a");
+      expect(a.className).not.toContain("active");
+      expect(a.className).toContain("selected");
+    });
+
     it("is not overwritten by the current location", () => {
       renderStrict(
         <MemoryRouter initialEntries={["/pasta"]}>

packages/react-router-dom/modules/utils/locationUtils.js

@@ -0,0 +1,10 @@
+import { createLocation } from "history";
+
+export const resolveToLocation = (to, currentLocation) =>
+  typeof to === "function" ? to(currentLocation) : to;
+
+export const normalizeToLocation = (to, currentLocation) => {
+  return typeof to === "string"
+    ? createLocation(to, null, null, currentLocation)
+    : to;
+};