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Clojurescript re-mount module, that takes care of setting up and providing web3 instance.


Add [district0x/district-ui-web3 "1.2.0"] into your project.clj
Include [district.ui.web3] in your CLJS file, where you use mount/start

API Overview

Warning: district0x modules are still in their early stages, therefore the API may change in the future.


This namespace contains web3 mount module. Once you start mount, it'll take care of web3 initialisation and will put results into re-frame db.

You can pass following args to initiate this module:

  • :url Url of Ethereum node to connect to
  • :wait-for-inject-ms Sometimes web3 isn't injected quickly enough by browser extension before an app starts. If it's not, this module will try to load it on second try after given milliseconds. Default: 1500
  (ns my-district.core
    (:require [mount.core :as mount]

  (-> (mount/with-args
        {:web3 {:url ""}})


re-frame subscriptions provided by this module:


Returns web3 instance.


Returns true if web3 was injected by browser extension, such as MetaMask.


Returns true if legacy web3 is available.

(ns my-district.home-page
  (:require [district.ui.web3.subs :as web3-subs]
            [re-frame.core :refer [subscribe]]))

(defn home-page []
  (let [web3-injected? (subscribe [::web3-subs/web3-injected?])]
    (fn []
      (if @web3-injected?
        [:div "This browser injected web3 instance"]
        [:div "This browser didn't inject web3 instance"]))))


Returns true if the current browser uses the legacy method of retrieving the web3 instance. This is true for browsers that are not implementing EIP-1102.

re-frame events provided by this module:

::create-web3-legacy [opts]

Will create and save web3 instance, either by using one injected from a browser extension (e.g MetaMask), if available, or will create one from given :url. Normally you don't need to use this event, as it's fired by ::start while in legacy-mode.

::create-web3 [opts]

This will first call window.ethereum.enable() and depending on the extension's implementation, will prompt the user if they would like to allow the ethereum provider. If accepted, it will create and save the web3 instance (e.g MetaMask).

If the browser does not support EIP-1102, or the ethereum provider is denied, it will fallback to using ::create-web3-legacy which will attempt to instantiate a personal web3 instance.

::web3-created [opts]

Event fired when web3 is created. Use this event to hook into event flow from your modules.
One example using re-frame-forward-events-fx may look like this:

    (:require [ :as web3-events]
              [re-frame.core :refer [reg-event-fx]]
  (fn []
    {:register :my-forwarder
     :events #{::web3-events/web3-created}
     :dispatch-to [::do-something]}))


re-frame effects provided this module:


EIP-1102 provides web3 providers with the ability to enable a privacy-mode. The ::authorize-ethereum-provider effect is necessary to ask for the correct permissions while users have privacy-mode enabled.

Keyword Parameters

:on-accept - If the ethereum provider is accepted, dispatches the provided event.

:on-reject - If the ethereum provider is rejected, dispatches the provided event.

:on-error - If there is no ethereum provider, and no legacy provider, dispatches the provided event

:on-legacy - If there is no ethereum provider, and a legacy provider, dispatches the provided event

  (fn [{:keys [:db]} [{:keys [:url] :as opts}]]
     {:on-accept [::create-web3]
      :on-reject [::create-web3-legacy opts]
      :on-error [::create-web3-legacy opts]
      :on-legacy [::create-web3-legacy opts]}}))

  • The ::authorize-ethereum-provider is automatically dispatched within the re-mount cycle.


DB queries provided by this module:
You should use them in your events, instead of trying to get this module's data directly with get-in into re-frame db.

web3 [db]

Returns web3 instance.

web3-injected? [db]

Returns true if web3 was injected by browser extension, such as MetaMask.

web3-legacy? [db]

Returns true if legacy web3 is available.

    (:require [district.ui.web3.queries :as web3-queries]
              [re-frame.core :refer [reg-event-fx]]))

  (fn [{:keys [:db]}]
    (if (web3-queries/web3-injected? db)
      {:dispatch [::do-something]}
      {:dispatch [::do-other-thing]})))

web3-legacy? [db]

Returns true if the browser is using the legacy implementation of resolving an ethereum provider. Note that this can mean that the browser does not have an extension that resolves an ethereum provider.

assoc-web3 [db {:keys [:web3 :web3-injected? :web3-legacy?]}]

Associates this module and returns new re-frame db.


lein deps

# To run tests and rerun on changes
lein doo chrome tests

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