Mapping reference

Where

Function	Map it to	Becomes
`webToAppRequest(class, method)`	the method JavaScript calls (`@JavascriptInterface`)	`onWebToAppRequest`
`webToAppResponse(class, method)`	the method that sends the result back to the page	`onWebToAppResponse`
`appToWebRequest(class, method)`	the method that calls into the page	`onAppToWebRequest`
`appToWebResponse(class, method)`	the method the page calls with its answer	`onAppToWebResponse`

class is the fully qualified class name. Nested classes may use . or $.
method is the method name. Every overload with that name is mapped.
The hook runs when the method starts, before its body.
suspend functions work too. A suspend function is called again each time it resumes; only the first call is recorded. --info shows (suspend; resumptions skipped) next to the method.

Fields

Field	Used by	Notes
`handlerName`	requests (required), `webToAppResponse`	Responses fall back to the request's name.
`requestId`	all; required for responses	Pairs a response with its request.
`data`	all	Text is stored as is. Bytes (from `base64(...)` or a `ByteArray` parameter) go through the protobuf API.
`displayName`	requests	Same as the manual `displayName` overload.
`success`	responses	Leave it out for "always SUCCESS". `false`, `"false"` or `0` record ERROR.
`fireAndForget`	requests	`true` resolves the entry at once. `false` defers to `DariConfig.fireAndForget`, like passing `null` by hand.
`onlyIf`	all	Optional. Leave it out to record every call. When set, the call is recorded only when it evaluates to `true`; `null` counts as `false`. For one method that carries several kinds of message.
`tag`	all	Overrides `dari { tag }` for this mapping.

Expressions

Expression	Value
`arg("name")`	The parameter called `name`. The plugin turns it into an index at build time.
`arg(n)`	The method's `n`th parameter, starting at 0 (`this` doesn't count).
`constant("x")`, `constant(true)`	A fixed value.
`json(expr, "a.b.0")`	A field from a JSON string, a JSON object such as kotlinx.serialization's `JsonObject` or Gson's `JsonObject` (anything whose `toString()` is JSON), or a nested `json(...)`. A value that isn't JSON yields `null`.
`base64(expr)`	Base64 text decoded to bytes.
`expr.equalsTo("x")`	`true` when the value's text equals `"x"`.
`isNull(expr)`	`true` when the value is `null`, e.g. a missing `error` field.

Prefer arg("requestId") to arg(1). With indexes, swapping two parameters or inserting one still builds and quietly records the wrong values. With names, the build fails when a parameter is renamed or removed, and the error lists the method's actual parameter names. Names come from debug info: Kotlin always writes it, and Java does with the default -g. Each overload of a mapped method is resolved on its own, and every one of them needs the name.

Options

dari {
    tag = "Checkout"                         // default: the name passed to addJavascriptInterface
    scope = InstrumentationScope.ALL         // default: InstrumentationScope.PROJECT
    failOnUnmatchedMapping = false           // default: true; see "Mapping check" in Rules and limits
}

scope takes AGP's own InstrumentationScope (com.android.build.api.instrumentation); Dari doesn't define it. Add import com.android.build.api.instrumentation.InstrumentationScope at the top of the build script. The plugin passes the value to AGP's transformClassesWith:

PROJECT: only the module's own classes.
ALL: also the classes of its dependencies, including third-party AARs.

Mapping reference

Where

Fields

Expressions

Options

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