Issue in card layout

What do you mean by "showing a task"?

Would you please provide some details.

As a preparation I suggest reading this: codeblog.jonskeet.uk/.../

I want to show task in interface through card layout which is in tempo.

I am not sure if we are in the same page how tasks are working in appian
-> what do you mean by "showing as task"? meta details? 

That somebody can "work on a task", for that you need an accordingly maintained interface.
A cardlyout itself, is a interface element which is used in certain ways within an interface.
So this question is really confusing....

You basically need to create

1. A task report
2. An expression rule that queries the task report
3. An interface to show the queried details inside a card layout!

Ya thats my need 

I have created task report and now I want to show report data in card layout.

a!localVariables(
  local!statuses:{
    "Assigned",
    "Accepted",
    "Delivered",
    "In transit",
  },
  filterValue:null,
  a!sectionLayout(
    contents: {
      a!dropdownField(
        label: "Status" ,
        placeholder: "Select status",
        choiceLabels: {
          "Assigned",
          "Accepted",
          "Delivered",
          "In transit"},
          choiceValues:enumerate(4) ,
          value: local!filterValue,
          saveInto: local!filterValue


      ),
      a!gridField(
        label: "My Report",
        data: a!queryProcessAnalytics(
          report: cons!CTA_ShowReport,
          query: a!query(
            filter:a!queryFilter(
              field: "c1",
              operator: "=",
              value: local!filterValue,
              applywhen:not( isnull(local!filterValue))
            ), 
            paginginfo:fv!pagingInfo
          )
        ),
        columns: {
          a!gridColumn(
            label: "name",
            value: a!linkField(
              links: a!processTaskLink(
                label: fv!row.c0,
                task: fv!identifier
              )
            )
          ),
          a!gridColumn(
            label: "process model",
            value: fv!row.c2
          ),
          a!gridColumn(
            label: "Status",
            value:if(
              not(isnull(fv!row.c1)),
              index(local!statuses,tointeger(fv!row.c1)+1,"other"),
              "other"
            )
          ),
          a!gridColumn(
            label: "Assigne By",
            value: a!forEach(
              items: fv!row.c4,
              expression: if(
                runtimetypeof(fv!item)=4,
                user(fv!item,"firstName"),
                group(fv!item,"groupName")
              )
            )
)
          
        },
        rowHeader: 1
      )
    }

  )
)

hint:
you can put the task report results directly into the gridfield like you did.
or you are loading it into a local.
kind of like this:

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a!localVariables(
 local!report: a!queryProcessAnalytics(
   report: cons!AT_MY_TASKS_REPORT
 ),
 a!textField(readOnly: true, value: local!report)
)

Then you can exchange the textfield with a card layout and use textfields

As per the above code, just put your gridField inside a card layout and you should be done.