@evidence-dev/sdk
v1.4.5
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How it works
The Evidence SDK contains all the tools needed to build interactive data apps, all the way from the database to the browser.
- Datasource Connectors - Plugins to connect to a variety of datasoures, including Databases, APIs, Flat files, and more
- Run queries in the browser - Universal SQL is the fastest way to use DuckDB WASM with your databases
Installation
- (If needed), create your SvelteKit project (e.g.
npm create svelte
) - Install the SDK
npm i @evidence-dev/sdk@preview
- Add the SDK to your project using
npx evidence-sdk add
- Use
npx evidence-sdk plugins install
if you did not install a plugin duringadd
5. If the data source you want to use is not listed, and there is an Evidence plugin for it, you can install the package and add it toevidence.config.yaml
manually. - Create a new connection with
npx evidence-sdk connections edit
- Once the connection is created, there will be a new
sources/[connection]
directory, for most connectors, you will need to create some source queries.
- Once the connection is created, there will be a new
- Populate the data with
npx evidence-sdk sources
Usage
See the wiki
There are 2 methods for executing queries using the Evidence SDK; using <code/>
elements, and calling runQuery
directly.
<code/>
elements automatically make their results available to child components (or pages, if used in a layout), while
runQuery
keeps the query scoped to the current page.
Using <code/>
Writing Queries
To add a query to your page, use a <code/>
element with an evidence-query-name
attribute (lang=sql
is optional but recommended).
Wrapping this in a <pre>
tag will prevent formatters from changing your SQL.
Example:
<pre><code evidence-query-name="myFirstQuery" lang="sql">
SELECT * FROM my_first_table
</code></pre>
When using <code/>
, you can interpolate variables from the page using template string syntax, Svelte syntax is not supported.
Working Example:
<pre><code evidence-query-name="myFirstQuery" lang="sql">
SELECT * FROM my_first_table WHERE user_id = '${selectedUserId}'
</code></pre>
Broken Example:
<pre><code evidence-query-name="myFirstQuery" lang="sql">
SELECT * FROM my_first_table WHERE user_id = '{selectedUserId}'
</code></pre>
Accessing Queries
To load queries that are placed on the page, create a reference to the queries store from $evidence/queries
<script>
import { getQueries } from '$evidence/queries';
const queries = getQueries();
/** @type {import("@evidence-dev/query-store").QueryStore} */
let { myFirstQuery } = $queries;
$: ({ myFirstQuery } = $queries);
</script>
$queries
is a set of QueryStore
based on what is provided on the page.
Full Example
<script>
import { getQueries } from '$evidence/queries';
const queries = getQueries();
/** @type {import("@evidence-dev/query-store").QueryStore} */
let { myFirstQuery } = $queries;
$: ({ myFirstQuery } = $queries);
</script>
<pre><code evidence-query-name="myFirstQuery" lang="sql">
SELECT * FROM my_first_table
</code></pre>
{#if !$myFirstQuery.loaded}
<!--
The query has not yet loaded.
$myFirstQuery.loading is also available,
but will be false if the store has not yet started to load.
QueryStore should begin loading automatically when attempting to access data,
but can be induced with .fetch()
-->
Loading...
{:else if $myFirstQuery.error}
<!-- An error has been encountered -->
Error: {$myFirstQuery.error.message}
{:else}
<!-- Results have been loaded -->
{#each $myFirstQuery as row (row.id)}
Row ID: {row.id}
{:else}
No resuls available
{/each}
{/if}
Using runQuery
Full Example
<script>
import { runQuery } from '$evidence/queries';
const myFirstQuery = runQuery('myFirstQuery', 'SELECT 1');
myFirstQuery.fetch(); // This is not done for you when using runQuery
// Queries can by dynamic
let x = 0;
// declare here to ensure it is defined
let dynamicQuery = runQuery('dynamicQuery', `SELECT ${x}`);
// react to updates in the query string
$: dynamicQuery = runQuery('dynamicQuery', `SELECT ${x}`);
$: dynamicQuery.fetch();
</script>
<!-- Usage is the exact same as above -->
{#if !$myFirstQuery.loaded}
<!--
The query has not yet loaded.
$myFirstQuery.loading is also available,
but will be false if the store has not yet started to load.
QueryStore should begin loading automatically when attempting to access data,
but can be induced with .fetch()
-->
Loading...
{:else if $myFirstQuery.error}
<!-- An error has been encountered -->
Error: {$myFirstQuery.error.message}
{:else}
<!-- Results have been loaded -->
{#each $myFirstQuery as row (row.id)}
Row ID: {row.id}
{:else}
No resuls available
{/each}
{/if}
Enabling SSR
If you are using the <code/>
method, all you need to do is make sure the server hook is installed.
If you are using the runQuery
method, you will need to use the <QuerySSR/>
component.
Configuring SSR Hook
Ensure that you have a
./src/hooks.server.[js|ts]
fileCreate or update the
handle
function to match:- To create:
import { ssrHook } from '$evidence/ssrHook.svelte.js'; /** @type {import('@sveltejs/kit').Handle} */ export async function handle({ event, resolve }) { /** @type {{ name: string, queryString: string}[]} */ const presentQueries = []; const response = await resolve(event, { transformPageChunk: ssrHook(presentQueries) }); return response; }
- If you already use
resolve
andtransformPageChunk
, you can chain the functions like so:
import { ssrHook } from '$evidence/ssrHook.svelte.js'; /** @type {import('@sveltejs/kit').Handle} */ export async function handle({ event, resolve }) { /** @type {{ name: string, queryString: string}[]} */ const presentQueries = [] const evidenceChunkTransform = ssrHook(presentQueries) const response = await resolve(event, { transformPageChunk: ({html, done}) => { // ... Do something to html html = await evidenceChunkTransform({ html, done }) // ... Do other things to html return html }); return response; }
Using <QuerySSR/>
<QuerySSR/>
registers your queries with the Evidence Preprocessor, which enables correct rehydration of your queries.
<script>
import { runQuery } from '$evidence/queries';
import QuerySSR from '$evidence/QuerySSR.svelte';
let manualQuery = runQuery('x', `SELECT * FROM users`);
$: manualQuery = runQuery('x', `SELECT * FROM users`);
</script>
<QuerySSR queries={[manualQuery]} />