XML Form Editor

Editing XML by hand is unpleasant and error-prone: one mistyped value or lost closing tag, and you only find out when the code that reads the file fails.

XML Form Editor opens an XML file as a form instead. You change the values, and add and remove the items of lists as far as the schema allows, and the rest of the file stays as it was. It was written for the input files of IMAS codes, but it works with any XML file that has an XSD schema. The form is built from the schema, which the file names in its root element with xsi:noNamespaceSchemaLocation or xsi:schemaLocation.

Features

• Dropdowns for enumerations, and checkboxes for booleans.
• Matrices show as a grid, like a spreadsheet, with their rows and columns numbered. A matrix is an element that the schema lets hold one repeating element of a list of numbers, one per row, such as <row>0.0 1.0</row>. Enter and the arrow keys move between the cells. The + buttons add a row or a column, and hovering a row or column number shows a button that removes it.
• Lists: when the schema allows more than one of an element, its items are numbered, as in time [0]. The Add button below a list adds an item, a copy of the last one, and the × on an item removes it, as far as the schema allows. An empty list keeps its Add button, which adds an item with the elements and attributes the schema requires.
• Values are written as you type, as soon as you pause, and picks and checkboxes straight away. Values are checked as you type, and invalid values are never written.
• Keys and unique constraints (xs:key, xs:unique and xs:keyref) are checked: a name used twice is marked on each element that has it, with the others it clashes with.
• Every setting shows its documentation and units from the schema.
• Changed values are marked green until you save, then blue. Save is enabled while a file differs from what's saved, so editing a value back as it was disables it again. Cancel discards the unsaved changes, after asking.
• Sections that an enumeration such as method doesn't choose are dimmed and collapsed.
• Filter the settings, and copy the path of any setting.
• Settings split across files: when an element links to another XML file with href, the form shows that file's settings in its place, so you can search and edit them all from one form. Click the file's name beside the section to open it in a form of its own. Save saves every file you changed. Until then, the form holds the changes to a linked file itself: VS Code opens a tab for every file with unsaved changes, so it would otherwise open one for each linked file you change. Open the file, and its tab shows them as unsaved changes. The changes the form holds are backed up, and if VS Code closes before you save, the form has them again when it next shows the file.
• Schemas: open an XSD in the form editor to see the form it describes, with every element and attribute it declares, its documentation, type and units, and how many of it the schema allows, such as optional or 1 or more. The fields are greyed out, as a schema has no values, and the page is dark green, so it can't be mistaken for a file's form.

Each change edits only the text it needs to, so formatting, comments and Undo keep working.

Getting started

Open an XML file and click Open Form Editor to the Side in the editor title bar, or right-click the file in the Explorer and choose Open in Form Editor. Save with Ctrl+S. XSD files open the same way.

Limitations

• The form adds and removes only the items of lists and the rows of a matrix: other elements and attributes, such as an optional setting the file leaves out, are added in the text, and so is a change to which file an element links to. Open XML in the toolbar opens the text beside the form.
• Without a schema, the form can't tell that an element is an item of a list unless there's more than one of it.
• The schema must be a local file, and xs:include, xs:import and xs:redefine aren't supported.
• The form checks values, missing and unexpected elements and attributes, and keys, but not the order of the elements in an xs:sequence, nor that only one branch of an xs:choice is used. Keys are compared as text, so 1.0 and 1 differ, and each file's are checked on their own.
• Undo in the form undoes changes to the file you opened, but not those the form holds for a linked file: change those back in the form, or discard them with Cancel. VS Code's Save All doesn't save them either; the form's Save and Ctrl+S do.