Headers

HTTP headers are case-insensitive, order-preserving, and allow multiple fields with the same name.

Quick API

• h[name] / h.get(name) → folded string (values joined with ", ").
• h[name] = value / h.set(name, value) → replace all fields for that name.
• del h[name] / h.delete(name) → remove all fields for that name.
• h.get_all(name) → list of values in order.
• h.set_all(name, values) → explicit multi-field set.
• h.insert(index, name, value) → insert raw field at index.
• h.items(multi=false) → iterate (raw if multi=true).

Common tasks

Read/Write a header

{{#tabs global="language"}} {{#tab name="Lua"}}

local h = flow.request.headers
print(h["host"])
h["X-Trace"] = "abc123"

{{#endtab}} {{#tab name=“JS”}}

const h = flow.request.headers;
console.log(h.get("host"));
h.set("X-Trace", "abc123");

{{#endtab}}

{{#tab name=“Python”}}

h = flow.request.headers
print(h["host"])
h["X-Trace"] = "abc123"

{{#endtab}} {{#endtabs}}