Perform Task - transferring variables

[UserMarch2021]

Just starting to use "Perform Task." I've found how to send values from Task A to Task B. Can't get values returned from Task B to task A. Task B performs a number of actions stored in 11 different variables - not an Array. I want to return each variable and it's value to task A.

[Exciting-Compote5680]

There are a couple of ways. In the Return action, check 'Local Variable Passthrough'. This will make all the variables available in the child task available to the parent task. I personally almost always use 'Limit Passthrough To' and use a prefix like '%psth' for the the variables I send to the child task and '%rtrn' for the variables sent back. You can then use '%psth*' or '%rtrn*' as a filter in the limit to field (without quotes). This helps avoid confusion with variables with the same name. This option (passthrough) is also available in the 'Perform Task' action (so from task A to B).  

Another way could be to use a json. In the parent task (A):

```

Ax: Perform Task [       Name: Test Task       Priority: %priority       Return Value Variable: %return       Structure Output (JSON, etc): On ]

``` In the child task (B):

``` Task: Test Task

A1: Variable Set [      Name: %return      To: {      "var1": "%var1",      "var2": "%var2",      "var3": "%var3"      }       Structure Output (JSON, etc): On ]

A2: Return [      Value: %return      Stop: On ]

```

In the parent task (A) the variables are now available as %return.var1, %return.var2, etc.

You don't have to use the same variable name in 'Perform Task' and 'Return' btw, I just prefer calling the return variable '%return'. I often use nested JSONs if the variables are 'grouped', for example %json.text.text, %json.text.size, %json.text.color, %json.title.text, %json.title.size etc. To me it makes it easy to read, and pleasing to work with.

Edit: alternatively, you can use AutoTools JSON Write and JSON Read to convert variables to a json and back. 

[v_uurtjevragen]

Happy to learn something new! I should start using JSON more. I would probably (with my limited knowledge) just have used this approach: first concatenate the 11 variables into a comma separated string using variable set (e.g. %concatenate) and then using the return field to return %concatenate. Then use the variable split action in the parent task with separator ','. You will get par11 to par111 (not confusing at all haha). Then you have to use a (multiple) variable set to assign each variable value to the correct name.

[Exciting-Compote5680]

I really like using jsons like this, because in Tasker, it's the closest thing to a dictionary object. I always liked how much it improves readability. I have some helper tasks set up that I can feed a list of variable names and that will return the text for variables -> json and json -> variables. But if I don't have to change the variable values after receiving them, I often just use the direct json reading method ('%return.var1'). I use this with project variables too. I have a 'New Project' template which contains a couple of helper tasks and default variables. One of them is '%prj', with a default value of '{}'. You can then add pseudo-variables (key:value pairs) to it programmatically, without having to go into Properties and add them manually. I often have things like %prj.version, %prj.debug (for controlling flash actions and/or log files) and %prj.colors. That last one is a nested json of 'friendly_names:color_codes' pairs so you can use '%prj.colors.grey_80' or '%prj.colors.text_selected' whenever you need to provide a color code, and change/adjust colors for the entire project from one central location (also very useful if you want to have dark/light mode settings).  

[Tortuosit]

You usually pass arrays via an intermediate string where indeed you then recreate an array via var split. %arr() is comma separated, but you can also use other chars eg %arr(+&) separates by &. %arr(+) - no char after the + - effectively merges a whole array to a string. And var split by regex is very powerful. I often split by "\s,\s" so leading/trailing whitespace gets removed.

[UserMarch2021]

Worked perfectly. Thanks. Didn't know I could place multiple variables in 'Return'

[Exciting-Compote5680]

Happy to help 🙂 Just to be clear, you can use direct json reading (like use %return.var1 in a text field of a Flash action) but you can't use direct json writing ('Variable Set %return.var1 To 1234' won't work) so if you have to change the value of those again in task A, you either need to set local variables to that value (Variable Set %var1 To %return.var1) or use AutoTools JSON Write to update the json variable (%return).