Add feedback to wikidata-input, fix #1650

langs/en.json

@@ -785,7 +785,9 @@
             "feedback": "This is not a valid web address"
         },
         "wikidata": {
-            "description": "A Wikidata identifier"
+            "description": "A Wikidata identifier",
+            "empty": "Please, enter some wikidata-entries",
+            "startsWithQ": "A wikidata identifier starts with Q and is followed by a number"
         }
     }
 }

src/UI/InputElement/Validators/WikidataValidator.ts

@@ -2,6 +2,8 @@ import Combine from "../../Base/Combine"
 import Wikidata from "../../../Logic/Web/Wikidata"
 import WikidataSearchBox from "../../Wikipedia/WikidataSearchBox"
 import { Validator } from "../Validator"
+import { Translation } from "../../i18n/Translation"
+import Translations from "../../i18n/Translations"
 
 export default class WikidataValidator extends Validator {
     constructor() {
@@ -12,12 +14,23 @@ export default class WikidataValidator extends Validator {
         if (str === undefined) {
             return false
         }
-        if (str.length <= 2) {
+        if (str.length == 1) {
             return false
         }
         return !str.split(";").some((str) => Wikidata.ExtractKey(str) === undefined)
     }
 
+    getFeedback(s: string, _?: () => string): Translation | undefined {
+        const t = Translations.t.validation.wikidata
+        if (s === "") {
+            return t.empty
+        }
+        if (!s.match(/(Q[0-9]+)(;Q[0-9]+)*/)) {
+            return t.startsWithQ
+        }
+        return undefined
+    }
+
     public reformat(str) {
         if (str === undefined) {
             return undefined