feat: variable, input and output support for custom dashboards

[AdityaHegde]

#5231

Remaining Items

• Lint fixes
• Support special characters as arguments in Data query
• Support platform validation for Vega specs with args inside them
• Change type for show to string and link with variables store

Spec for select component

# Chart YAML
# Reference documentation: https://docs.rilldata.com/reference/project-files/charts
    
type: component

data:
  metrics_sql: |
    SELECT advertiser_name, measure_2
    FROM Bids_Sample_Dash
    LIMIT 250

output: 
  name: selection
  value: Leafly

select:
  placeholder: No selection
  valueField: advertiser_name
  label: Advertiser name

Sample Spec for Bar template with variable

kind: component

input:
 - name: selection
   type: string
   value: Instacart

data:
  metrics_sql: |
    SELECT
    time_grain_hour,
    measure_2
    FROM
        Bids_Sample_Dash
    WHERE
        __time >= '2023-03-06T00:30:00.000Z' 
        AND __time < '2023-03-08T00:30:00.000Z'
        AND advertiser_name = '{{ .args.selection }}'
    ORDER BY
        time_grain_hour DESC
    LIMIT 200
    OFFSET 0

bar_chart:
  x: time_grain_hour
  y: measure_2

Sample dashboard spec

type: dashboard
columns: 20
gap: 1

variables:
  - name: selection
    type: string
    value: Instacart

items:
  - component: horizontal_bar_chart
    height: 6
    width: 11
    x: 4
    y: 12
  - component: kpi_template
    height: 2
    width: 5
    x: 4
    y: 2
  - component: kpi_template
    height: 2
    width: 6
    x: 9
    y: 2
  - component: selection
    height: 1
    width: 5
    x: 5
    y: 1
  - component: stacked_area_chart
    height: 4
    width: 11
    x: 4
    y: 8
  - component: image
    height: 1
    width: 1
    x: 4
    y: 1
  - component: bar_template
    height: 4
    width: 11
    x: 4
    y: 4

[begelundmuller]

Since the response here is structured and pretty small, it would probably be better to define an RPC with protocol buffers for it

[begelundmuller]

Are these fmt.Printlns leftover from debugging?

[begelundmuller]

It's not safe to rely on file loading from APIs that are used for dashboard serving because the files may be unavailable (for example, if the Github clone takes a long time or Github is unavailable). Viewer roles also are not allowed to have any way of loading files for security reasons.

So it should only use fields in res (which are available for querying as soon as the server is up).

[begelundmuller]

Here's a PR that adds an RPC that addresses the above issues with the parseTemplate and componentDataHandler APIs: #5362.

Stale