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transformations:iteratewebrequest

ITERATE WEB REQUEST

Category: Workflow / External


Description

This action sends multiple uniform HTTP requests to a web server. Requests are configured using values from columns of the input dataset. One request is sent for each line of the input dataset. Responses can be automatically appended into one dataset or saved as files into a designated folder. This action requires a configured Web Location connector.

Supports all HTTP methods - GET, POST, PUT, DELETE, HEAD, OPTIONS, CONNECT, TRACE, PATCH.

To simplify development and debugging, the action has a preview pane that shows the first raw HTTP request that would be sent as well as a response preview.


Use cases

The action is intended for repeating uniform interactions with REST APIs, cloud applications, and websites.


Action settings

Setting Description
Connector/Base URL*Select or create a Web Location connector, or enter the base URL for the request. Select between "Connector" and
"Base URL" using the selector to the left of the input field.
Request methodSelect the request method. Options: GET, HEAD, POST, PUT, DELETE, CONNECT, OPTIONS, TRACE, and PATCH.
Path**See "Path setting", below.
Add URL parameters**Check to insert parameters into the URL. See "URL parameters", below, for details.
Body**See "Request Body settings", below.
Headers**See "Request Headers settings", below.
Response**See "Response settings", below.

* Setting can be specified using a parameter.
** Setting can be specified using a parameter or the values in a selected table column.

Path setting

The URL path is appended to the endpoint URL specified in the Web Location connector. EasyMorph parameters can be inserted into the path using curly braces if needed. Alternatively, the entire path can be specified with a parameter or using the values in a specified column.

Examples:

Web Location endpoint Web Request path Actual HTTP request URL Notes
https://example.com/api/v3 products https://example.com/api/v3/products
https://example.com/api/v3 product/123 https://example.com/api/v3/product/123
https://example.com/api/v3 product/{ProductID} https://example.com/api/v3/product/123 Assuming {Product ID} = 123


URL parameters

URL parameters can be specified as name-value pairs. They will be encoded and appended as a URL query. Value can be omitted, if needed. In this case, only the name will be appended to the URL query.

Example:

Web Location endpoint Web Request path Name Value Actual HTTP request URL
https://example.com/api/v3 orders year 2019 https://example.com/api/v3/orders?year=2019

If a Web Location connector has permanent URL parameters specified they will be appended to all requests that are made using the connector. This can be used for scenarios where all requests should have an API key or secret specified.


Request Body settings

The request body can be specified in one of the following ways:

JSON
This body type is suitable for sending simple JSONs. The JSON object is constructed from a list of name-value pairs. Both name and value can be specified with a parameter or using values in a specified column. If the value itself is a JSON object/array it's inserted verbatim thus allow object nesting.

When this body type is selected header "Content-Type:application/json" is set automatically.

Example:

Name Value
Country CA
ProvinceON
Name EasyMorph
Incorporated 2014
Tags ["ETL", "analytics", "dataprep", "automation"]

Resulting request body (JSON):

{
  "Country":"CA",
  "Province":"ON",
  "Name":"EasyMorph",
  "Incorporated":2014,
  "Tags":["ETL", "analytics", "dataprep", "automation"]
}


Column
This body type uses the values in a selected column for the body.


Form
This body type is equivalent to submitting a web form. Name-value pairs are encoded as if it was a web-form.

Header Content-Type is automatically set to "application/x-www-form-urlencoded".

Example:

Name Value
Country CA
ProvinceON
Name EasyMorph
Incorporated 2014


Resulting request body:

Country=CA&Province=ON&Name=EasyMorph&Incorporated=2014


File
The request body is read from the specified file and inserted verbatim.


Request Headers settings

Additional request headers can be specified. Header names and values can be specified either explicitly, using parameters, or using values in a specified column.

Note that header Content-Length is calculated and added to every request automatically.

If a Web Location connector has permanent headers specified they will be added to all requests that are made using the connector. This can be used for scenarios where all requests should have an API key or secret.


Response settings

There are 3 modes for how a response would be processed in the Web Request action:

Return no data, fail if HTTP error
In this case, if the response status is not an error (i.e. HTTP status codes 4xx or 5xx) then the response will be ignored. This is basically a "fire-and-forget" mode that is intended for submitting data and updates to remote endpoints.

Return response as the action result
In this mode, the response (error or not) is always received and transformed into a 1-row dataset in EasyMorph. The column names in such a dataset correspond to the response body, response status, and response headers (one column per header).

Save response body to file, fail if HTTP error
In this case, if the response status is not an error (i.e. HTTP status codes 4xx or 5xx) then the response body (only the body!) will be saved verbatim into the specified file (the filename of which can be created automatically, or specified using values in a specified column).


Remarks

The action is very similar to the Web Request action, except that it's intended for sending multiple requests instead of one, and its properties can be specified using column values besides constants and parameters.


Cookies

Currently, there is no way to set HTTP cookies explicitly in the Web Request action. Under the hood, all cookies that come with responses to web requests are automatically stored in a cookie container that exists only during project execution. Cookies from the container are automatically appended to outgoing requests made using the same Web Location connector. If a project workflow includes calls/iterations, the cookie container is passed to called/iterated modules or projects which in turn can add new cookies to it. This can be used for cookie-based web sessions.

When project execution is finished, the cookie container is discarded. No cookies are stored in the project or Web Location connector.

When developing workflows with web requests it may be necessary to re-run parts of workflows. In this case, it is recommended to always start from the Web Request actions that do authentication so that the session cookies can be set under the hood.


Community examples


See also

transformations/iteratewebrequest.txt · Last modified: 2021/08/14 21:38 by craigt