Two ways to merge

Create a merger

A merger is a data source of its own, which you create in the back end:

The merging tree

The tree always starts with one group, Vertical merge by default. Drag data sources into it in the order you want them, and drag them up or down to reorder. The group's list switches it between Vertical — append rows and Horizontal — append columns.

Groups can contain other groups. Click + Vertical group or + Horizontal group in a group to add one inside it. In the example above:

1. The horizontal group puts the Patras delivery status next to the Patras orders, row by row.
2. The vertical group then stacks the Athens orders, the Thessaloniki orders and the combined Patras rows.

The Patras rows are wider, so the Athens and Thessaloniki rows get empty cells in the delivery columns. Groups are evaluated from the inside out, and they can be nested up to 30 levels deep.

Show/Hide JSON shows the tree as the merger stores it, which is handy for checking a complex tree. Clear starts again with an empty vertical group.

{
  "type": "vertical",
  "children": [
    { "type": "source", "tag": "orders_athens", "title": "Orders - Athens store" },
    { "type": "source", "tag": "orders_thessaloniki", "title": "Orders - Thessaloniki store" },
    { "type": "horizontal", "children": [
        { "type": "source", "tag": "orders_patras", "title": "Orders - Patras store" },
        { "type": "source", "tag": "patras_delivery", "title": "Patras delivery status" }
    ] }
  ]
}

Rulesets: before and after the merge

Two kinds of ruleset take part, and each has its own job:

• Each source's own ruleset runs first, on that source alone. Use it for what belongs to the source: removing columns you do not need, formatting its dates, fixing its values. A rule that removes a column in one source changes what the merge receives.
• The merger's ruleset runs on the combined table. Use it for everything the visitor sees as one table: styling, sorting, search, pagination, and cleaning up after the merge.

Repeated header rows

The merger does not know which row is a header. In a vertical merge, the header row of the second and later sources ends up in the middle of the table as an ordinary row, as the diagram above shows. Remove it in one of two ways:

• In the ruleset of every source except the first, add a Data Removal rule for Row 1. The source then no longer shows its header when you use it on its own, either.
• Or, better, add one Data Removal rule to the merger's ruleset: Row, with the range SAME U3RvcmU= [1]^1. It removes every row whose first cell is exactly "Store" (U3RvcmU= in base64), except row 1. In the wizard's range window this is Text, operator SAME, text "Store", subrange 1, with ^1 typed at the end.

See Tutorial 2 for more on removal rules.

Things to know