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transformations:webrequest

Web Request

Category: Workflow / External

Sends a single HTTP request to a web server and receives a response. Intended for interactions with REST APIs, cloud applications and websites. 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 raw HTTP request that would be sent as well as a response preview.

Path

The URL path is appended to the endpoint URL specified in 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.

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 URL query. Value can be omitted, in needed. In this case, only the name will be appended to the URL query.

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

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. 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"]
}

Text

This body type specifies body as a free-form text with parameters inserted, if needed.

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

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

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

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

Fail if HTTP error, otherwise ignore

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 “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 dataset correspond to response body, response status, and response headers (one column per each header).

Fail if HTTP error, otherwise save response body into file

In this case, if the response status is not an error (i.e. HTTP status codes 4xx or 5xx) then the response body (only body!) will be saved verbatim into the specified file.

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 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.

See also

transformations/webrequest.txt · Last modified: 2019/10/31 15:17 by dmitry