Add allowSpaceAsAnswer (false by default) non-serializable property i…

src/question.ts

@@ -1385,7 +1385,7 @@ export class Question extends SurveyElement<Question>
       if (res) return res;
     }
     value = value == undefined ? this.createValueCopy() : value;
-    if (this.isValueEmpty(value)) return this.getDisplayValueEmpty();
+    if (this.isValueEmpty(value, !this.allowSpaceAsAnswer)) return this.getDisplayValueEmpty();
     return this.getDisplayValueCore(keysAsText, value);
   }
   protected getDisplayValueCore(keyAsText: boolean, value: any): any {
@@ -1574,7 +1574,7 @@ export class Question extends SurveyElement<Question>
     return this.defaultValue;
   }
   protected isDefaultValueEmpty(): boolean {
-    return !this.defaultValueExpression && this.isValueEmpty(this.defaultValue);
+    return !this.defaultValueExpression && this.isValueEmpty(this.defaultValue, !this.allowSpaceAsAnswer);
   }
   protected getDefaultRunner(runner: ExpressionRunner, expression: string): ExpressionRunner {
     if (!runner && !!expression) {
@@ -1686,7 +1686,7 @@ export class Question extends SurveyElement<Question>
    * Returns `true` if the question value is an empty string, array, or object or if it equals `undefined` or `null`.
    */
   public isEmpty(): boolean {
-    return this.isValueEmpty(this.value);
+    return this.isValueEmpty(this.value, !this.allowSpaceAsAnswer);
   }
   public get isAnswered(): boolean {
     return this.getPropertyValue("isAnswered");
@@ -1902,11 +1902,12 @@ export class Question extends SurveyElement<Question>
       this.onCompletedAsyncValidators = null;
     }
   }
+  public allowSpaceAsAnswer: boolean;
   private isValueChangedInSurvey = false;
   protected allowNotifyValueChanged = true;
   protected setNewValue(newValue: any): void {
     if(this.isNewValueEqualsToValue(newValue)) return;
-    if(!this.isValueEmpty(newValue) && !this.isNewValueCorrect(newValue)) {
+    if(!this.isValueEmpty(newValue, !this.allowSpaceAsAnswer) && !this.isNewValueCorrect(newValue)) {
       ConsoleWarnings.inCorrectQuestionValue(this.name, newValue);
       return;
     }
@@ -1922,7 +1923,7 @@ export class Question extends SurveyElement<Question>
   }
   protected isNewValueEqualsToValue(newValue: any): boolean {
     const val = this.value;
-    if(!this.isTwoValueEquals(newValue, val)) return false;
+    if(!this.isTwoValueEquals(newValue, val, false, false)) return false;
     const isObj = newValue === val && !!val && (Array.isArray(val) || typeof val === "object");
     return !isObj;
   }

src/survey.ts

@@ -6078,7 +6078,7 @@ export class SurveyModel extends SurveyElementCore
     )
       return;
     var oldValue = this.getValue(name);
-    if (this.isValueEmpty(newValue)) {
+    if (this.isValueEmpty(newValue, false)) {
       this.deleteDataValueCore(this.valuesHash, name);
     } else {
       newValue = this.getUnbindValue(newValue);

tests/question_texttests.ts

@@ -411,3 +411,35 @@ QUnit.test("CharacterCounter + settings.showMaxLengthIndicator", function(assert
   ch.updateRemainingCharacterCounter("abcd", 7);
   assert.equal(ch.remainingCharacterCounter, "4/7", "#4");
 });
+
+QUnit.test("Set empty text", function(assert) {
+  const survey = new SurveyModel({
+    elements: [{ type: "text", name: "q1" }]
+  });
+  const q = survey.getQuestionByName("q1");
+  q.value = " ";
+  assert.equal(q.isEmpty(), true, "question.isEmpty() #1");
+  assert.equal(q.value, " ", "question.value #1");
+  assert.deepEqual(survey.data, { q1: " " }, "survey.data #1");
+  q.value = "a";
+  assert.equal(q.isEmpty(), false, "question.isEmpty() #2");
+  assert.equal(q.value, "a", "question.value #2");
+  assert.deepEqual(survey.data, { q1: "a" }, "survey.data #2");
+  q.value = " a ";
+  assert.equal(q.isEmpty(), false, "question.isEmpty() #3");
+  assert.equal(q.value, " a ", "question.value #3");
+  assert.deepEqual(survey.data, { q1: " a " }, "survey.data #3");
+  q.allowSpaceAsAnswer = true;
+  q.value = " ";
+  assert.equal(q.isEmpty(), false, "question.isEmpty() #4");
+  assert.equal(q.value, " ", "question.value #4");
+  assert.deepEqual(survey.data, { q1: " " }, "survey.data #4");
+  q.value = "a";
+  assert.equal(q.isEmpty(), false, "question.isEmpty() #5");
+  assert.equal(q.value, "a", "question.value #5");
+  assert.deepEqual(survey.data, { q1: "a" }, "survey.data #5");
+  q.value = " a ";
+  assert.equal(q.isEmpty(), false, "question.isEmpty() #6");
+  assert.equal(q.value, " a ", "question.value #6");
+  assert.deepEqual(survey.data, { q1: " a " }, "survey.data #6");
+});