Fix #1630 - triggering search via URL

src/frontend/next/src/components/SearchPage.tsx

@@ -1,4 +1,4 @@
-import { FormEvent, useState } from 'react';
+import { FormEvent, useState, useEffect } from 'react';
 import { makeStyles } from '@material-ui/core/styles';
 import { useRouter } from 'next/router';
 
@@ -23,12 +23,10 @@ const SearchPage = () => {
   // We synchronize the `text` and `filter` values to the URL's query string
   // Router query object for a query can be an array if url becomes text=123&text=456
   // https://stackoverflow.com/questions/60110364/type-string-string-is-not-assignable-to-type-string
-  const [textParam = '', setTextParam] = useState(
-    Array.isArray(router.query.text) ? router.query.text[0] : router.query.text
-  );
-  const [filterParam = 'post', setFilterParam] = useState<FilterProp['filter']>(
-    router.query.filter === 'post' ? 'post' : 'author'
-  );
+  const textParam = Array.isArray(router.query.text)
+    ? router.query.text[0]
+    : router.query.text || '';
+  const filterParam = router.query.filter === 'post' || !router.query.filter ? 'post' : 'author';
 
   // We manage the state of `text` and `filter` internally, and update URL on
   // form submit only.  These are used in the <SearchBar>, and the user can change them.
@@ -38,11 +36,14 @@ const SearchPage = () => {
   // Form was submitted, so go ahead and sync to URL, (re)triggering search.
   function onSubmitHandler(event: FormEvent) {
     event.preventDefault();
-    setTextParam(text);
-    setFilterParam(filter);
     router.push(`/search?text=${text}&filter=${filter}`);
   }
 
+  useEffect(() => {
+    setText(textParam);
+    setFilter(filterParam);
+  }, [textParam, filterParam]);
+
   return (
     <div>
       <div className={classes.anchor} id="back-to-top-anchor" />