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File metadata and controls

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tree-view-demo

This is a demo of the fin-hypergrid-tree-view-plugin which shows hierarchical data on a self-joined table.

Using the plugin

To use the fin-hypergrid-tree-view-plugin plug-in, the following requirements must be met:

  • The data has:
    • A primary key
    • A foreign key
  • The data source implements setters and getters for:
    • idColumn (name or column index) - The column containing the primary key. Defaults to 'ID'.
    • parentIdColumn (name or column index) - The column containing the foreign key Defaults to 'parentID'.
    • treeColumn (name or column index) - The column displaying the decorations described below Defaults to 'name'.
    • groupColumn (name or column index) - The column to be group-sorted. Defaults to treeColumn.
    • join (boolean) - Whether or not the table is in the joined state.
  • When in the joined state (dataSource.join = true), the data source decorates values in the "tree" column with:
    • An indent to reflect the degree of descent.
    • A drill-down control string for rows with children. Initially, all controls are set to closed and the child rows are hidden. Controls are sticky and remember their settings while hidden.

The datasaur-tree-view data source implements the above, but is dependent on a findRowIndexByID and findRowIndexByParentID methods which it does not implement, as well as an underlying data source. An example data stack might be:

Data Source Description
datasaur-tree-view Implements the above setters and getters
datasaur-searchable Implements findRowIndexByID
datasaur-searchable Implements findRowIndexByParentID
datasaur-local The underlying data source that implements getValue, etc.

Typically, the ID and parentID columns are hidden from view.

Self-joined tables

A table with a self-join is a table with a foreign key (FK) that references the table's own primary key (PK) as its "parent" row.

A classic example of a self-joined table is a table representing a hierarchical file system, wherein each row represents a file in the file system. For example, consider the following typical file structure for a web site:

  • /index.html
  • /stylesheets/styles.css
  • /src/index.js
  • /src/data/js

If the above listing can be captured in a table like the following:

ID name parentID
1 NULL index.html
2 NULL stylesheets
3 NULL src
4 3 index.js
5 3 data.js
6 2 styles.css

parentID refers to the folder inside which this file (or folder) lives. The Files and folders in the root have no parent folder so their parentID columns are NULL.

(In this simple example any file can be a folder. More typically, rows would be tagged with an additional boolean column as either folders or files proper and parentID would be constrained to point only to rows tagged as folders.)