Help:Content changes
The normal process to change structured data (properties, property values) is via the editing process where a wiki page (which in SMW terms represents the master against its internal back-end is replicated) and its content is altered by a user.
Changing property values without changing the corresponding wiki page (where the data originates) via an SMW specific API is not supported because it is expected that the back-end and the wiki page are in sync and contain the same data.
Changes via a template[edit]
Alterations to a template will "bubble" down (which is the normal MW process) given that the refreshLinks job has finished and populated the changes.
Changes via the MW API[edit]
If changes to a wiki page are made via the MW API then registered extensions (incl. SMW) will pick up those changes and can adjust accordingly.
var mwApi = new mw.Api(), title = 'SomeTitleToBeEdietd', content = 'ContentIWantToChange'; mwApi.postWithToken( "edit", { action: "edit", title: title, section: 0, // Existing content will be replaced // summary: section, // no need for a section heading text: content } ).done( function( result, jqXHR ) { // Do something } ).fail( function( code, result ) { // Report something } );
Semantic Cite example creating content (together with property and property value assignments) via the API.