HTML & Templates
MARS is not only for JSON APIs — it can serve HTML, static files and server-rendered pages. This is handy for admin panels, landing pages, dashboards, or hypermedia front-ends (htmx). Several integrations are available; pick the one that fits your stack.
Serving static files
TFileSystemResource (MARS.WebServer.Resources) maps a URL path to a folder on disk. Subclass it and point [RootFolder] at the directory:
uses MARS.WebServer.Resources;
type
[Path('www/{*}'), RootFolder('.\www', True)]
TStaticContentResource = class(TFileSystemResource)
end;{*}captures the remainder of the URL as the file path within the root.- The second
[RootFolder]argument (True) enables serving an index document for directory requests. [RootFolder]supports placeholders like{bin}for the executable folder, e.g.RootFolder('{bin}\..\..\..\www\swagger-ui-3.52.5-dist', True)— used to ship Swagger UI (see OpenAPI).
This is also how the SSEDemo and OpenAPI/Swagger setup serve their HTML/JS assets.
Returning HTML from a method
Any method can return an HTML string with [Produces(TMediaType.TEXT_HTML)]:
[GET, Produces(TMediaType.TEXT_HTML)]
function Home: string;
begin
Result := '<!doctype html><h1>Hello</h1>';
end;For anything beyond trivial markup, use a template engine instead of string concatenation.
WebStencils
Embarcadero's WebStencils template engine integrates via TMARSWebStencils, injected with [Context]. You register variables and datasets, then render a template file:
[Path('helloworld')]
THelloWorldResource = class
protected
[Context] FWS: TMARSWebStencils;
public
[GET, Path('/{datasetName}'), Produces(TMediaType.TEXT_HTML)]
function RenderDataset([PathParam] datasetName: string): string;
end;
function THelloWorldResource.RenderDataset(datasetName: string): string;
var
LTable: TFDMemTable;
begin
LTable := TFDMemTable.Create(nil);
try
LTable.LoadFromFile(DatasetFileFor(datasetName));
LTable.Name := datasetName;
FWS.AddVarValue('datasetName', datasetName);
FWS.AddDataVar('dataset', LTable, True); // True: WebStencils owns it
except
LTable.Free;
raise;
end;
Result := FWS.ContentFromFile('dataset.html'); // template iterates over @dataset
end;The template can iterate collections and bind values, producing fully server-rendered HTML backed by live FireDAC data. See the WebStencilsDemo.
htmx
htmx lets you build dynamic pages where HTML fragments are fetched and swapped into the DOM via attributes like hx-get / hx-target, with no SPA framework. MARS pairs naturally with it: expose endpoints that return JSON (or HTML fragments) and let htmx drive the page.
The HtmxDemo reads the application's own OpenAPI document at runtime and returns a list of endpoints that the page renders client-side:
function THelloworldResource.RetrieveData([Context] AOpenAPI: TOpenAPI): TDataResponse;
begin
Result := Default(TDataResponse);
for var LPath in AOpenAPI.paths do
begin
var LEndpoint := TEndpoint.Create(LPath.Key, LPath.Value.Methods);
LEndpoint.summary := LPath.Value.summary;
Result.endpoints := Result.endpoints + [LEndpoint];
end;
end;DelphiRazor
For projects already using DelphiRazor, the MARS.DelphiRazor.* units provide an injection service and resources to render Razor (.cshtml-style) templates from MARS endpoints, following the same [Context]-injection pattern as WebStencils.
Which to choose?
| Need | Use |
|---|---|
| Serve a folder of static assets | TFileSystemResource + [RootFolder] |
| Server-rendered pages with Delphi data | WebStencils (TMARSWebStencils) |
| Dynamic, partial-update UIs without a JS framework | htmx over JSON/HTML endpoints |
| Existing Razor templates | DelphiRazor integration |
| A pure SPA / mobile front-end | Just expose JSON; serve the built front-end as static files |