HttpCurl React Native Reference Documentation

HttpCurl

Current Version: 11.6.1

curl-style HTTP requests with dependency resolution

Run curl commands and automatically resolve values needed by later requests

The Chilkat.HttpCurl class executes HTTP requests expressed as curl commands, with support for variable substitution, reusable curl functions, automatic dependency resolution, response extraction, and structured diagnostics.

Variables such as {{access_token}}, {{site_id}}, or {{drive_id}} can appear in URLs, headers, query parameters, or request bodies. If a variable is not yet known, HttpCurl can build an execution plan from previously defined curl functions, run the prerequisite requests, extract values from JSON responses, and then execute the final target request.

Define dependencies Use AddFunction with AddOutput or AddOutput2.
Manage variables Use SetVar, GetVar, ClearVar, and GetAllVars.
Preview execution Use ExaminePlan or ToRawRequest before sending.
Read responses Get text, binary, JSON, XML, or stream directly to a file.

After DoYourThing completes, check StatusCode and retrieve the response using the appropriate getter. If something fails, FailReason, FailedCurl, and LastErrorText help identify the failed step and the reason.

Note: Chilkat.HttpCurl is not derived from curl/libcurl and does not wrap libcurl. It accepts curl-style command text and executes the request using Chilkat’s own HTTP implementation.

Object Creation

// npm install @chilkat/react-native react-native-nitro-modules
// (React Native 0.76+ with the New Architecture; then `pod install` for iOS.  The Chilkat
//  native library is downloaded and verified during the native build -- see the package README.)

import { Chilkat, HttpCurl } from '@chilkat/react-native'

// Once per app start, before any other Chilkat call:
Chilkat.unlockBundle('Anything for 30-day trial')   // shorthand for new Global().unlockBundle(..)

const httpCurl = new HttpCurl()
// ... the native object is released when `httpCurl` is garbage collected, or now with httpCurl.dispose()
new HttpCurl()

Creates the underlying native Chilkat object. HttpCurl is a Nitro Module HybridObject: use it from the JavaScript thread only (it cannot be passed to a Worklet or another runtime). Every member is synchronous and blocks the JavaScript thread until Chilkat returns; a method that can take a while also exists as a ...Async twin returning a Promise, which runs the same call on a native worker thread so the UI keeps rendering. While such a call is pending, every other call on this object throws, except abort() and assigning onPercentDone / onProgressInfo.

dispose(): void

Releases the native object immediately instead of waiting for garbage collection (useful for a large BinData or an open socket). Calling it more than once is harmless; any other use of the object afterwards throws. An object with a pending ...Async call cannot be disposed until the promise settles.

Errors

A method that can fail throws a plain Error: a method whose only outcome is success or failure returns void and throws on failure; a method producing a string or an object returns it and throws where Chilkat would have returned null. The error's message is "Class.method(...): reason", where the reason is the last informative line of the object's lastErrorText, which holds the full Chilkat log of the failed call. A ...Async twin rejects its promise with the same Error instead of throwing. Properties never throw, and methods that answer a question (has..., is..., ...) return a plain boolean.

try {
  httpCurl.someMethod(...)
} catch (e) {
  console.log((e as Error).message)   // HttpCurl.someMethod(...): <reason>
  console.log(httpCurl.lastErrorText)   // the full Chilkat log of the failed call
}

// The same call without blocking the JavaScript thread:
try {
  await httpCurl.someMethodAsync(...)
} catch (e) {
  console.log((e as Error).message)   // HttpCurl.someMethodAsync: <reason>
}

Properties

DebugLogFilePath
// read/write
debugLogFilePath: string

If set to a file path, this property logs the LastErrorText of each Chilkat method or property call to the specified file. This logging helps identify the context and history of Chilkat calls leading up to any crash or hang, aiding in debugging.

Enabling the VerboseLogging property provides more detailed information. This property is mainly used for debugging rare instances where a Chilkat method call causes a hang or crash, which should generally not happen.

Possible causes of hangs include:

  • A timeout property set to 0, indicating an infinite timeout.
  • A hang occurring within an event callback in the application code.
  • An internal bug in the Chilkat code causing the hang.

More Information and Examples
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EnableBodyVars
// read/write
enableBodyVars: boolean
Introduced in version 11.5.0

Enables variable substitution in the body of the request. The default value is true.

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FailedCurl
// read-only
readonly failedCurl: string
Introduced in version 11.5.0

Set to the specific curl command in the execution plan that failed.

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FailReason
// read-only
readonly failReason: number
Introduced in version 11.5.0

Set to an integer value indicating the reason for failure for the methods DoYourThing and ExaminePlan

Possible values are:

  1. No error - the method succeeded or hasn't yet been called.
  2. curl command syntax error.
  3. HTTP response status code indidcates an authentication (401) or authorization (403) error.
  4. HTTP response status code indicates an error, but not an authentication or authorization error.
  5. HTTP communications failure.
  6. Impossible to derive an execution plan from defined outputs and inputs.
  7. A step in the execution plan did not resolve any dependency variables.
  8. Failed to get curl data from a local file source (see the note below).
  9. If we are within a Chilkat.Js context and don't have permission to read the local filesystem.
  10. Chilkat has not been successfully unlocked by previously and successfully calling UnlockBundle.
  11. Failed to open or create the local output file (if a curl option directed output to a file).

Note: curl can read data from a local file and send it in a request (usually POST/PUT) using special syntax:

  • -d @file.txt → reads the file and sends it as request body (form-style encoding).
  • --data-binary @file.bin → sends raw file contents exactly as-is.
  • -F "file=@file.txt" → uploads the file as multipart/form-data.

The @ tells curl to load the data from a local file instead of using a literal string.

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HeartbeatMs
// read/write
heartbeatMs: number
Introduced in version 11.5.0

Specifies the interval, in milliseconds, between AbortCheck event callbacks.

This allows an application to periodically decide whether a long-running operation should be aborted.

The default value is 0, which means no AbortCheck callbacks are generated.

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LastErrorHtml
// read-only
readonly lastErrorHtml: string

Provides HTML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.

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LastErrorText
// read-only
readonly lastErrorText: string

Provides plain text information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.

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LastErrorXml
// read-only
readonly lastErrorXml: string

Provides XML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.

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LastMethodSuccess
// read/write
lastMethodSuccess: boolean

Indicates the success or failure of the most recent method call: true means success, false means failure. This property remains unchanged by property setters or getters. This method is present to address challenges in checking for null or Nothing returns in certain programming languages. Note: This property does not apply to methods that return integer values or to boolean-returning methods where the boolean does not indicate success or failure.

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ResponseBodyStr
// read-only
readonly responseBodyStr: string
Introduced in version 11.5.0

Returns the HTTP response body from the last call to DoYourThing .

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ResponseFilePath
// read/write
responseFilePath: string
Introduced in version 11.5.0

Set this property to the path of a file to stream the response body to a file. If the response is streamed to a file, it will not be available in ResponseBodyStr , GetResponseSb , or GetResponseBd .

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StatusCode
// read-only
readonly statusCode: number
Introduced in version 11.5.0

Returns the HTTP status code from the last call to DoYourThing. A value of 0 indicates no response header was received.

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UncommonOptions
// read/write
uncommonOptions: string
Introduced in version 11.5.0

Provides a comma-separated list of uncommon option keywords.

This property defaults to an empty string and should normally remain empty.

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VerboseLogging
// read/write
verboseLogging: boolean

If set to true, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. The default value is false. Verbose logging should only be used for debugging. The potentially large quantity of logged information may adversely affect peformance.

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Version
// read-only
readonly version: string

Version of the component/library, such as "10.1.0"

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Methods

AddFunction
addFunction(funcName: string, curl: string): void
Introduced in version 11.5.0

Adds a named curl function that can be used in dependency resolution. Inputs required by the curl function are indicated by the variable names enclosed in {{ and }}. Outputs are defined in one or more calls to AddOutput .

Returns normally on success; throws an Error on failure.

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AddOutput
addOutput(funcName: string, jsonPath: string, varName: string): void
Introduced in version 11.5.0

Adds or updates a defined output for a dependency resolution curl function previously defined by calling AddFunction. The jsonPath is the JSON path in the JSON response body where the varName's value is located. If either the funcName or jsonPath already exist for the funcName, then the output is updated.

Returns normally on success; throws an Error on failure.

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AddOutput2
addOutput2(funcName: string, arrayPath: string, wherePath: string, whereValue: string, caseSensitive: boolean, subPath: string, varName: string): void
Introduced in version 11.5.0

Adds or updates an output variable definition for a dependency-resolution curl function previously created by calling AddFunction. Use this method when the curl response is JSON containing an array of objects, and a value needs to be extracted from one specific array element.

The method searches the array located at arrayPath, finds the array element where the value at wherePath matches whereValue, and then extracts the value at subPath. The extracted value is assigned to the variable named by varName.

The wherePath and subPath values are paths relative to each individual array element. The comparison between whereValue and the JSON value found at wherePath is either case-sensitive or case-insensitive depending on the value of caseSensitive.

Parameters

  • funcName — The name of the curl function previously added by calling AddFunction. The output definition is associated with this function.
  • arrayPath — The JSON path identifying the array of records within the JSON response.
  • wherePath — A relative JSON path within each array element used to locate the matching record.
  • whereValue — The value to match against the JSON value found at wherePath.
  • caseSensitive — If true, the comparison between whereValue and the JSON value is case-sensitive. If false, the comparison is case-insensitive.
  • subPath — A relative JSON path within the matched array element identifying the value to extract.
  • varName — The name of the variable that will receive the extracted value.

Example

Given the following JSON response:

{
  "drives": [
    {
      "name": "Documents",
      "id": "A123"
    },
    {
      "name": "Shared",
      "id": "B456"
    }
  ]
}

The following call:

AddOutput2("GetDrive","drives","name","shared",false,"id","drive_id")

searches the drives array for the element whose name matches "shared" using case-insensitive comparison. The matching element is:

{
  "name": "Shared",
  "id": "B456"
}

The value of id is extracted and assigned to the variable drive_id, resulting in:

drive_id = "B456"

Returns normally on success; throws an Error on failure.

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AddTargetOutput
addTargetOutput(jsonPath: string, varName: string): void
Introduced in version 11.5.0

Adds an automatically mapped variable for the target curl command. When a JSON response is received from a curl request, the value at the JSON path specified by jsonPath is extracted (if present) and assigned to the variable named by varName.

This is useful in common workflows where one request returns an identifier (such as an `id`) that must be reused in a subsequent curl request.

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ClearTargetOutput
clearTargetOutput(varName: string): void
Introduced in version 11.5.0

Clears (undefines) the target output for the specified varName. If varName equals "*", then all target outputs are cleared.

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ClearVar
clearVar(varName: string): void
Introduced in version 11.5.0

Undefines the variable with the specified name. If varName equals "*", then all variables are cleared.

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DoYourThing
doYourThing(targetCurl: string): void
Introduced in version 11.5.0

Runs a the targetCurl command specified in targetCurl. If the targetCurl contains variable names enclosed in {{ and }}, then an execution plan is constructed from defined functions and outputs to resolve unknown variables, and the execution plan is run. The final step in the execution plan is always the targetCurl command.

Returns success (true) if a response was received, in which case the response status code will be available in StatusCode and the content of the response body will be available in one of two places:

Assuming the HTTP response is JSON, the target outputs (variables) specified by prior calls to AddTargetOutput will be populated by applying each variable's JSON path to the response JSON.

Returns normally on success; throws an Error on failure.

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DoYourThingAsync
doYourThingAsync(targetCurl: string): Promise<void>
Introduced in version 11.5.0

Asynchronous form of DoYourThing: the same call on a native worker thread, so the JavaScript thread (and the UI) stays responsive. Takes the same arguments and resolves with the same result. While the returned Promise is pending, every other call on this object throws (the object is busy), except abort(), which cancels the call, and assigning the onPercentDone / onProgressInfo callbacks, which report its progress.

Note: the onPercentDone and onProgressInfo callbacks run on the JavaScript thread while the promise is pending, so they can update the UI directly. A rejection's message is "Class.methodAsync: reason"; the full log is in lastErrorText.

Returns a Promise that resolves with the synchronous method's result (undefined for a void method) and rejects with an Error where the synchronous method would throw.

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ExaminePlan
examinePlan(curl: string, json: JsonObject): void
Introduced in version 11.5.0

Used for debugging. Returns in json the plan of execution that would occur for the curl based on the variables that are either unknown or already known. The plan of execution is what would occur if DoYourThing was called with the current state of knowledge.

If no execution plan is possible with the current known inputs and outputs, then json provides information about what is missing and the method returns false.

Returns normally on success; throws an Error on failure.

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GetAllVars
getAllVars(json: JsonObject): void
Introduced in version 11.5.0

Returns all defined variables in json.

More Information and Examples
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GetResponseBd
getResponseBd(bd: BinData): void
Introduced in version 11.5.0

Appends to bd the HTTP response body from the last call to DoYourThing.

Returns normally on success; throws an Error on failure.

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GetResponseJarr
getResponseJarr(jarr: JsonArray): void
Introduced in version 11.5.0

Writes to jarr the HTTP response body from the last call to DoYourThing.

Returns normally on success; throws an Error on failure.

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GetResponseJson
getResponseJson(json: JsonObject): void
Introduced in version 11.5.0

Writes to json the HTTP response body from the last call to DoYourThing.

Returns normally on success; throws an Error on failure.

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GetResponseSb
getResponseSb(sb: StringBuilder): void
Introduced in version 11.5.0

Appends to sb the HTTP response body from the last call to DoYourThing.

Returns normally on success; throws an Error on failure.

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GetResponseXml
getResponseXml(xml: Xml): void
Introduced in version 11.5.0

Writes to xml the HTTP response body from the last call to DoYourThing.

Returns normally on success; throws an Error on failure.

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GetVar
getVar(varName: string): string
Introduced in version 11.5.0

Retrieves the current value of the variable specified by varName.

Throws an Error on failure (where the description says null is returned, the method throws instead).

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SetAuth
setAuth(json: JsonObject): void
Introduced in version 11.5.0

Sets authorization information that is applied to all calls to DoYourThing . See the examples below for details.

Returns normally on success; throws an Error on failure.

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SetVar
setVar(varName: string, varValue: string): void
Introduced in version 11.5.0

Sets the value of a variable to be replaced in curl commands. Variable names are enclosed in {{ and }} and can occur in the path, query params, or the body of the request.

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ToRawRequest
toRawRequest(curlCommand: string, sb: StringBuilder): void
Introduced in version 11.5.0

Used for debugging purposes. This method behaves the same as DoYourThing , but only converts the curlCommand to an HTTP request message in sb containing the full structure:

  • start line
  • headers
  • optional body or multipart body

It does not actually send the HTTP request.

Returns normally on success; throws an Error on failure.

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VarDefined
varDefined(varName: string): boolean
Introduced in version 11.5.0

Returns true if the varName is defined, otherwise returns false. Setting varName to "!" checks whether all target output variables have been defined. It returns true if every target output is set, and false if any are missing.

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Events

While a method runs, HttpCurl reports progress through two optional callback properties. Assign a function to receive the event, or undefined to stop receiving it. The callbacks are delivered on the JavaScript thread, so they are useful with the ...Async methods: during a synchronous call the JavaScript thread is busy inside Chilkat, and the events can only arrive after it returns.

const httpCurl = new HttpCurl()
httpCurl.onPercentDone = (pct) => setProgress(pct)          // pct is 0..100
httpCurl.onProgressInfo = (name, value) => console.log(`${name}: ${value}`)
httpCurl.heartbeatMs = 250   // let abort() take effect within a quarter second

const pending = httpCurl.someMethodAsync(...)
cancelButton.onPress = () => httpCurl.abort()   // the promise then rejects
await pending

PercentDone fires when an operation's completion percentage is known; ProgressInfo delivers named progress values (what is reported depends on the class and method). There is no AbortCheck callback: to cancel a pending ...Async call, call abort() on the object. Chilkat notices the request at its next progress check, which happens at least every heartbeatMs milliseconds on the classes that have that property (0, the default, disables the heartbeat, so set it for a responsive cancel), and the promise rejects with Chilkat's abort error. abort() is harmless when nothing is pending.

PercentDone
// callback property; assign undefined to remove
onPercentDone?: (pctDone: number) => void

This provides the percentage completion for any method involving network communications or time-consuming processing, assuming the progress can be measured as a percentage. This event is triggered only when it's possible and logical to express the operation's progress as a percentage. The pctDone argument will range from 1 to 100. For methods that finish quickly, the number of PercentDone callbacks may vary, but the final callback will have pctDone equal to 100. For longer operations, callbacks will not exceed one per percentage point (e.g., 1, 2, 3, ..., 98, 99, 100).

The PercentDone callback also acts as an AbortCheck event. For fast methods where PercentDone fires, an AbortCheck event may not trigger since the PercentDone callback already provides an opportunity to abort. For longer operations, where time between PercentDone callbacks is extended, AbortCheck callbacks enable more responsive operation termination.

To abort the operation, set the abort output argument to true. This will cause the method to terminate and return a failure status or corresponding failure value.

More Information and Examples

Example:

httpCurl.onPercentDone = (pct) => {
  // pct ranges from 0 to 100.
  setProgress(pct)   // runs on the JavaScript thread: React state may be updated directly
}
await httpCurl.someMethodAsync(...)
// To stop an operation from within the callback, call httpCurl.abort()
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ProgressInfo
// callback property; assign undefined to remove
onProgressInfo?: (name: string, value: string) => void

This event callback provides tag name/value pairs that detail what occurs during a method call. To discover existing tag names, create code to handle the event, emit the pairs, and review them. Most tag names are self-explanatory.

Note: Some Chilkat methods don't fire any ProgressInfo events.

More Information and Examples

Example:

httpCurl.onProgressInfo = (name, value) => console.log(`${name}: ${value}`)
await httpCurl.someMethodAsync(...)
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