Difference expression between two values

[ilaplain15115]

Are you requesting a feature, reporting a bug or asking a question?

Asking a question

What is the current behavior?

Current expression is not calculating the difference between pre and post values

What is the expected behavior?

Pressure delta calculation should show the difference between Pre and Post (Pre-Post)

How would you reproduce the current behavior (if this is a bug)?

Provide the test code and the tested page URL (if applicable)

Tested page URL:

Test code

{
 "title": "GitHub",
 "logoPosition": "right",
 "pages": [
  {
   "name": "page1",
   "elements": [
    {
     "type": "paneldynamic",
     "name": "question4",
     "title": "Question 1",
     "questionCategory": "surveyquestion",
     "templateElements": [
      {
       "type": "matrixdropdown",
       "name": "Pre1",
       "title": "Pressure Machine",
       "hideNumber": true,
       "questionCategory": "surveyquestion",
       "showHeader": false,
       "columns": [
        {
         "name": "Pre.1",
         "cellType": "text",
         "inputType": "number"
        }
       ],
       "choices": [
        1,
        2,
        3,
        4,
        5
       ],
       "cellType": "text",
       "rows": [
        "Enter Pre Value"
       ]
      },
      {
       "type": "matrixdropdown",
       "name": "Post1",
       "startWithNewLine": false,
       "title": "    ",
       "hideNumber": true,
       "questionCategory": "surveyquestion",
       "showHeader": false,
       "columns": [
        {
         "name": "Post.1",
         "cellType": "text",
         "inputType": "number"
        }
       ],
       "horizontalScroll": true,
       "choices": [
        1,
        2,
        3,
        4,
        5
       ],
       "cellType": "text",
       "rows": [
        "Enter Post Value"
       ]
      },
      {
       "type": "expression",
       "name": "question6",
       "title": "Pressure Calculation",
       "hideNumber": true,
       "questionCategory": "surveyquestion",
       "expression": "{row.Pre1} - {row.Post1}"
      }
     ],
     "allowAddPanel": false,
     "allowRemovePanel": false,
     "panelCount": 1
    }
   ]
  }
 ]
}

Specify your

• browser: Chrome
• browser version: 119.0.6045.160
• surveyjs platform (angular or react or jquery or knockout or vue): Angular
• surveyjs version: 1.9.112

[andrewtelnov]

@ilaplain15115 "row." prefix works for columns in the same row in the same matrix. 1) You have your expression question in the dynamic panel and it means that you have to use "panel." prefix instead of "row." 2) Pre1 and Post1 are matrix dropdowns. They are question value in the format:

{ 
  row1_Value: { column1: column1Value, column2: column2Value, ... }, 
  row2_Value: { column1: column1Value, column2: column2Value } 
}

Our expression question could not perform any arithmetic operations for two values in this format.

Thank you, Andrew