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ContentAsString

property ContentAsString: string read write;

Example​

procedure ScriptEvent(var Value: variant);
begin
  Http.Content.Clear;
  Http.ContentAsString := '{"reference":"DEMO-1001"}';
  Http.Header['Content-Type'] := 'application/json; charset=utf-8';
  Http.Post('https://api.example.invalid/v1/messages');
  Value := Http.Response.ResponseCode;
end;

Usage​

ContentAsString writes BOM-free UTF-8 but reads by BOM detection with a host-ANSI fallback, making its two directions intentionally asymmetric.

Additional Technical Info​

ContentAsString is not a symmetric “default encoding” property. Writing always uses BOM-free UTF-8. Reading detects only a leading UTF-8, UTF-16 little-endian or UTF-16 big-endian byte-order mark, removes that preamble and decodes accordingly; without one of those BOMs it falls back to the Velox host's Windows ANSI code page.

The write path calls the shared stream helper at position zero. It emits no UTF-8 BOM and never truncates the existing Content stream. If the new UTF-8 representation is shorter, stale tail bytes remain in the request; assigning '' changes nothing. Always call Content.Clear first when replacing a body.

The read path is BOM recognition rather than content or HTTP-header detection. It does not consult Content-Type, charset, XML declarations or JSON rules, and it does not infer BOM-free UTF-8. ASCII-only UTF-8 happens to survive the ANSI fallback, but non-ASCII text is host-dependent. For a known wire encoding, use the matching explicit ContentAs... property.

Reading consumes the complete stream and normally leaves its position at the end. Indy rewinds before transmission, so that side effect does not shorten a subsequent request. A malformed byte sequence in a BOM-selected UTF-8 body can raise. The full byte array and resulting string coexist in memory during conversion.

The body follows the one-shot and pre-terminal-retention rules documented under Content. Set a Content-Type value consistent with the write path; Velox does not do this automatically.

Related entries

External references

Created 2026-07-15