HttpCurl JavaScript Reference Documentation

HttpCurl

Current Version: 11.5.0

The Chilkat.HttpCurl class executes curl commands and can automatically resolve dependent values needed by a request.

Variables such as {{access_token}}, {{site_id}}, or {{drive_id}} may appear in URLs, headers, query parameters, or request bodies. If a variable is not yet known, HttpCurl builds an execution plan from previously defined curl functions, runs the required steps, extracts values from JSON responses, and then executes the final target request.

Use AddFunction with AddOutput or AddOutput2 to define how prerequisite values are obtained. Use SetVar to provide known values, ClearVar to invalidate them, and ExaminePlan to inspect the dependency plan before running it.

After DoYourThing completes, the response can be read as text, binary data, JSON, XML, or streamed directly to a file. Diagnostic properties such as StatusCode, FailReason, FailedCurl, and LastErrorText help troubleshoot failures.

Note: Chilkat's HttpCurl does not derived from curl/libcurl, and does not wrap libcurl.

See Also:
  • HttpCurl Overview — A more complete introduction to the HttpCurl class, including concepts, variable substitution, dependency resolution, and workflow examples.
  • Dependency Engine — Explains how HttpCurl automatically derives execution plans, resolves unknown variables, determines prerequisite requests, and manages cached variables.

Object Creation

Note: This is intended for running within a Chilkat.Js embedded JavaScript engine.

var obj = new CkHttpCurl();

Properties

DebugLogFilePath
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.

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EnableBodyVars
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
FailedCurl
· string, read-only
Introduced in version 11.5.0

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

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FailReason
FailReason
· int, read-only
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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LastErrorHtml
LastErrorHtml
· string, read-only

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
LastErrorText
· string, read-only

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
LastErrorXml
· string, read-only

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
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
ResponseBodyStr
· string, read-only
Introduced in version 11.5.0

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

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ResponseFilePath
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
StatusCode
· int, read-only
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
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
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
Version
· string, read-only

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

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Methods

AddFunction
var success = AddFunction(funcName, curl);
· return: boolean; true for success, false for failure
· funcName: string
· curl: string
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 true for success, false for failure.

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AddOutput
var success = AddOutput(funcName, jsonPath, varName);
· return: boolean; true for success, false for failure
· funcName: string
· jsonPath: string
· varName: string
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 true for success, false for failure.

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AddOutput2
var success = AddOutput2(funcName, arrayPath, wherePath, whereValue, caseSensitive, subPath, varName);
· return: boolean; true for success, false for failure
· funcName: string
· arrayPath: string
· wherePath: string
· whereValue: string
· caseSensitive: boolean
· subPath: string
· varName: string
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 true for success, false for failure.

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AddTargetOutput
AddTargetOutput(jsonPath, varName);
· return: undefined
· jsonPath: string
· varName: string
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.

Returns true for success, false for failure.

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ClearTargetOutput
ClearTargetOutput(varName);
· return: undefined
· varName: string
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);
· return: undefined
· varName: string
Introduced in version 11.5.0

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

Returns true for success, false for failure.

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DoYourThing
var success = DoYourThing(targetCurl);
· return: boolean; true for success, false for failure
· targetCurl: string
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 true for success, false for failure.

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ExaminePlan
var success = ExaminePlan(curl, json);
· return: boolean; true for success, false for failure
· curl: string
· json: CkJsonObject
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 true for success, false for failure.

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GetAllVars
GetAllVars(json);
· return: undefined
· json: CkJsonObject
Introduced in version 11.5.0

Returns all defined variables in json.

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GetResponseBd
var success = GetResponseBd(bd);
· return: boolean; true for success, false for failure
· bd: CkBinData
Introduced in version 11.5.0

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

Returns true for success, false for failure.

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GetResponseJarr
var success = GetResponseJarr(jarr);
· return: boolean; true for success, false for failure
· jarr: CkJsonArray
Introduced in version 11.5.0

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

Returns true for success, false for failure.

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GetResponseJson
var success = GetResponseJson(json);
· return: boolean; true for success, false for failure
· json: CkJsonObject
Introduced in version 11.5.0

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

Returns true for success, false for failure.

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GetResponseSb
var success = GetResponseSb(sb);
· return: boolean; true for success, false for failure
· sb: CkStringBuilder
Introduced in version 11.5.0

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

Returns true for success, false for failure.

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GetResponseXml
var success = GetResponseXml(xml);
· return: boolean; true for success, false for failure
· xml: CkXml
Introduced in version 11.5.0

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

Returns true for success, false for failure.

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GetVar
var strVal = GetVar(varName);
· return: string
· varName: string
Introduced in version 11.5.0

Retrieves the current value of the variable specified by varName.

Returns null on failure

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SetAuth
var success = SetAuth(json);
· return: boolean; true for success, false for failure
· json: CkJsonObject
Introduced in version 11.5.0

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

Returns true for success, false for failure.

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SetVar
SetVar(varName, varValue);
· return: undefined
· varName: string
· varValue: string
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.

Returns true for success, false for failure.

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ToRawRequest
var success = ToRawRequest(curlCommand, sb);
· return: boolean; true for success, false for failure
· curlCommand: string
· sb: CkStringBuilder
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 true for success, false for failure.

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VarDefined
var boolVal = VarDefined(varName);
· return: boolean
· varName: string
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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