how to validate extracted excel columns for data type and not null

a!localVariables(
  local!uploadedFile,
  local!showOptionalParameters: false,
  local!selectedSheetNumber,
  /*Sheet Number Selection  */
  local!sheetNumber: a!defaultValue(local!selectedSheetNumber, 0),
  local!selectedstartingColumn,
  /*Starting Column of Excel  */
  local!startingColumn: a!defaultValue(local!selectedstartingColumn, 1),
  local!selectedendingColumn,
  /*Ending Column of Excel  */
  local!endingColumn: a!defaultValue(local!selectedendingColumn, 100),
  /*Contents of excel that came after reading  */
  local!excelContents,
  /*Keys of the Excel  */
  local!keysOftheFile: if(
    a!isNullOrEmpty(local!excelContents.data),
    null,
    reject(
      fn!isnull,
      index(
        index(local!excelContents.data, 1, null),
        "values",
        null
      )
    )
  ),
  /*just values of the file  */
  local!contentsOftheFile: if(
    a!isNullOrEmpty(local!excelContents.data),
    null,
    a!forEach(
      items: remove(local!excelContents.data, 1),
      expression: a!forEach(
        items: fv!item.values,
        expression: if(
          fv!index > count(local!keysOftheFile),
          {},
          fv!item
        )
      )
    )
  ),
  /*Creating a dictionary out of excel  */
  local!createDictionaryWithFile: if(
    a!isNullOrEmpty(local!excelContents.data),
    null,
    a!flatten(
      a!forEach(
        items: local!contentsOftheFile,
        expression: createdictionary(local!keysOftheFile, fv!item)
      )
    )
  ),
  {
    a!cardLayout(
      contents: {
        a!richTextDisplayField(
          value: a!richTextIcon(
            icon: "refresh",
            caption: "Refresh",
            link: a!dynamicLink(
              saveInto: {a!save(local!uploadedFile,null),
             a!save(local!showOptionalParameters,false),
              a!save({local!selectedendingColumn,local!selectedSheetNumber,local!selectedstartingColumn,local!excelContents},null)
              }
            ),
            linkStyle: "STANDALONE"
          ),
          align: "RIGHT"
        ),
        a!fileUploadField(
          label: "Upload File",
          labelPosition: "ABOVE",
          instructions: "Upload files of type XLXS",
          /* Saving into Application Documentation    change it to your Folder     */
          target: cons!SB_FOLDER_APPLICATIONDOCUMENTATION ,
          maxSelections: 1,
          value: local!uploadedFile,
          saveInto: { local!uploadedFile },
          validations: {
            /* Accepts only XLXS           */
            if(
              fv!files.extension <> "xlsx",
              "Upload Exce File",
              null
            )
          }
        ),
        a!richTextDisplayField(
          /*Capturing additional details for reading          */
          value: a!richTextItem(
            text: {
              "Provide Optional Values to read Excel"
            },
            link: a!dynamicLink(
              saveInto: a!save(local!showOptionalParameters, true)
            )
            
          ),
          showWhen: and(
            a!isNotNullOrEmpty(local!uploadedFile),
            not(local!showOptionalParameters)
          )
        ),
        {
          if(
            local!showOptionalParameters,
            {
              a!integerField(
                label: "Sheet Number",
                value: local!sheetNumber,
                saveInto: local!selectedSheetNumber
              ),
              a!integerField(
                label: "Start Index",
                helpTooltip: "Row number to start reading ",
                value: local!startingColumn,
                saveInto: local!selectedstartingColumn
              ),
              a!integerField(
                label: "BatchSize",
                helpTooltip: "How many rows to read",
                value: local!endingColumn,
                saveInto: local!selectedendingColumn
              )
            },
            null
          )
        },
        a!buttonArrayLayout(
          buttons: {
            a!buttonWidget(
              label: "Read Excel",
              saveInto: {
                /*Saving submitted files                */
                a!submitUploadedFiles(
                  onSuccess: a!save(
                    local!excelContents,
                    readexcelsheetpaging(
                      todocument(local!uploadedFile),
                      local!sheetNumber,
                      a!pagingInfo(
                        local!startingColumn,
                        local!endingColumn
                      )
                    )
                  )
                )
              },
              style: "OUTLINE",
              showWhen: a!isNotNullOrEmpty(local!uploadedFile)
            )
          },
          align: "START",
          marginBelow: "NONE"
          
        ),
        a!gridField(
          label: "Excel Data",
          labelPosition: "ABOVE",
          emptyGridMessage: "Excel Does not contains Any Data",
          data: local!createDictionaryWithFile,
          columns: {
            a!forEach(
              /*Creating read only grid              */
              items: local!keysOftheFile,
              expression: a!gridColumn(
                label: fv!item,
                sortField: fv!item,
                value: index(fv!row, fv!item, null)
              )
            )
          },
          showWhen: a!isNotNullOrEmpty(local!excelContents),
          validations: {}
        )
      },
      height: "AUTO",
      style: "TRANSPARENT",
      marginBelow: "STANDARD"
    )
  }
)

I wrote similar code for reading Excel sheet and showing it on grid dynamically , Go through the local variables where i used reject function with flatten to read excel data , Make the necessary changes.

Thank you , I will try 

Thank you , I will try