Module string_source 

StringSource

When setting a URL part, you sometimes want to choose the value based on another part of the URL.

Almost all components that take string inputs actually take string sources. This is usually invisible because JSON string literals deserialize to StringSource::String.

For example, deviantart used to put the username in the subdomain (https://username.deviantart.com) but now puts them in the first path segment (https://deviantart.com/username).

To get the subdomain, StringSource::Part is used with UrlPart::Subdomain. Written in JSON as {"Part": "Subdomain"}.

To then remove the subdomain, Action::SetSubdomain is given StringSource::None, written in JSON as null.

{"If": {
  "if": {"All": [
    {"RegDomainIs": "deviantart.com"},
    {"Not": {"SubdomainIsOneOf": [null, "www"]}}
  ]},
  "then": {"All": [
    {"InsertPathSegmentAt": {
      "index": 0,
      "value": {"Part": "Subdomain"}
    }},
    {"SetSubdomain": null}
  ]}
}}

Complex construction

String sources can be very complex. A common example of this is StringSource::Modified.

For example, some redirect URLs encode the redirect in Base64 in a path segment. To clean these, you must first get that path segment then Base64 decode it (which, in URL Cleaner Engine, defaults to the URL safe alphabet).

{"Modified": {
  "value": {"Part": {"PathSegment": 1}},
  "modification": "Base64Decode"
}}

This might seem slightly inside out (it’s x.map(f) instead of f(x)) but it was the easiest way to design this.

For more information on what StringSource::Modified can do, see the tutorial on string modifications.

Additionally, there’s also StringSource::HttpRequest to do HTTP requests, StringSource::IfFlag, StringSource::Map, StringSource::ParamsMap, StringSource::NamedPartitioning, and so on for control flow, StringSource::Join for joining several other string sources, and so on.