How to get the a datasource row by index

General Questions
1

I am trying to get specific datasource row by index.
I have tried =(@ctx.datasources.questions)[0] and =@ctx.datasources.questions[0] without luck. In Jsonata I can do $[0] and it works.

any ideas?
Thanks

2

Hi @adam

Thanks for your question.

The last example you mentioned usually works for me, like in the below scenarios. You will see that I used [0] but also different indexing options like [2] (see the second scenario).

Perhaps you are using it in a different way, feel free to share your YAML with me and I will help you troubleshoot futher. Please also let me know where your data comes from (REST call maybe?).

title: Test Indexing
description: Description of your Jig
type: jig.default

header:
  type: component.jig-header
  options:
    height: medium
    children:
      type: component.image
      options:
        source:
          uri: https://builder.jigx.com/assets/images/header.jpg



datasources:
  mydata: 
    type: datasource.static
    options:
      data:
        - id: 1
          field1: value1
          field2: value1
        - id: 2
          field1: value2
          field2: value2
        - id: 3
          field1: value3
          field2: value3
        - id: 4
          field1: value4
          field2: value4

  mydataABC: 
    type: datasource.static
    options:
      data:
        - id: 1
          field1: valueA
          field2: valueA
        - id: 2
          field1: valueB
          field2: valueB
        - id: 3
          field1: valueC
          field2: valueC
        - id: 4
          field1: valueD
          field2: valueD
          
children:
  - type: component.list
    options:
      data: =@ctx.datasources.mydata
      maximumItemsToRender: 8
      item: 
        type: component.list-item
        options:
          title: =@ctx.current.item.field1
  
  - type: component.list
    options:
      data: =@ctx.datasources.mydataABC[0]
      maximumItemsToRender: 8
      item: 
        type: component.list-item
        options:
          title: =@ctx.current.item.field1

stories:
  type: component.story-group
  options:
    actionButtonTitle: Gimme more Deadpool
    data: =[@ctx.datasources.videos[19], @ctx.datasources.videos[10], @ctx.datasources.videos[0], @ctx.datasources.videos[1], @ctx.datasources.videos[2]]
    # data: =@ctx.datasources.videos[0]
    groupName: Deadpool - Because testing has to be FUN!
    item:
      type: component.video-player
      options:
        title: =$uppercase(@ctx.current.item.title) & 
        subtitle: ='Last updated by Chanelle Dicks on 22 February 2023'
        thumbnailUri: =@ctx.current.item.thumbnail #="https://i.ytimg.com/vi/" & @ctx.current.item.videoid & "/maxresdefault.jpg"
        url: ="https://www.youtube.com/watch?v=" & @ctx.current.item.videoid
        onPress: 
          type: action.go-to
          options:
            title: Gimme More Deadpool
            linkTo: deadpool-playlist

Regards,
Chanelle :smiley:

1 Like
3

Hey Adam

Both the examples above should have worked.
There must be something in your example or the data that is causing this to fail.

Here are some tricks with indexing that might help you solve the problem:

$.path.to.value means find the value relative to the current node (not the root of the supplied context) so all paths are relative to it.
$$.path.to.value means find the value relative the root node of the supplied context, no matter what is the current node. (internally we convert @ctx. to $$. when executing in expressions in jsonata).

Adding an empty array index [] in the path forces jsonata to return an array of one item vs the normal behavior where it returns the item directly.
ex: =@ctx.datasources.questions
[{}] => {}
[{},{}] => [{},{}]
ex: =@ctx.datasources.questions[]
[{}] => [{}] ← notice array of one
[{},{}] => [{},{}]

You can use the built-in index parameter from jsonata.
positional-variable-binding

This can be combined with a filter to get the correct result
ex: =@ctx.datasources.questions#$i.answer[$i=3]
JSONata exerciser

I hope this helps

4

Thanks all. No idea why it wasn’t working before.

I think the Jigx watcher was confusing me.

If you look at the below,
=@ctx.solution.state.question-index has a value of 3
=@ctx.datasources.questions[@ctx.solution.state.question-index].title returns a value
=@ctx.datasources.questions[3].title is empty
=$count(@ctx.datasources.questions) is empty

image
image1485×442 15.1 KB

2 Likes
5

Thanks for sharing your experience with us Adam. We’ll take a closer look and explore how we can enhance Jigx Watcher in our future releases. {ref:86867emg2}