8000 refactor: update debug doc to mention pretty printing debug queries · adonisjs/lucid.adonisjs.com@88595b4 · GitHub
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refactor: update debug doc to mention pretty printing debug queries
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‎content/docs/guides/debugging.md

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@@ -4,9 +4,9 @@ summary: A guide on debugging Lucid database queries.
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# Debugging
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Lucid emits the `db:query` event when debugging is enabled globally or for an individual query.
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You can debug SQL queries by first enabling the `debug` mode and then listen for the `db:query` event to get notified as SQL queries are executed.
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You can enable debugging globally by setting the `debug` flag to `true` inside the `config/database.ts` file.
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The debug mode can be enabled globally for a database connection by setting the `debug` flag to `true` inside the `config/database.ts` file. For example:
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```ts
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// title: config/database.ts
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})
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```
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You can enable debugging for an individual query using the `debug` method on the query builder.
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Or, you can enable it for an individual query using the `debug` method on the query builder.
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:::codegroup
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:::
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## Listening to the Event
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## Pretty printing debug queries
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Once the debugging has been enabled you can set the `prettyPrintDebugQueries` flag to `true` within the `config/database.ts` file.
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Once you have enabled debugging, you can listen for the `db:query` event using the [emitter](https://docs.adonisjs.com/guides/emitter) service.
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This flag will register an event listener for the `db:query` event and will print the SQL queries to the console.
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```ts
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// title: start/events.ts
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import emitter from '@adonisjs/core/services/emitter'
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// title: config/database.ts
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import env from '#start/env'
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import { defineConfig } from '@adonisjs/lucid'
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emitter.on('db:query', function ({ sql, bindings }) {
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console.log(sql, bindings)
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const dbConfig = defineConfig({
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// highlight-start
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prettyPrintDebugQueries: true,
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// highlight-end
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connection: 'postgres',
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connections: {
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postgres: {
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client: 'pg',
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connection: {
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// ...
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},
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debug: true
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},
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},
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})
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```
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### Pretty print queries
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## Manually listening for the event
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If you do not want to pretty print SQL queries and write them to the console, then you can self listen for the `db:query` event and self handle the treatment of debug logs.
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You can use the `db.prettyPrint` method as the event listener to pretty-print the queries on the console.
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In the following example, we use the application logger to log the queries.
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```ts
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// title: start/events.ts
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import emitter from '@adonisjs/core/services/emitter'
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import db from '@adonisjs/lucid/services/db'
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emitter.on('db:query', db.prettyPrint)
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```
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## Debugging in production
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Pretty printing queries add additional overhead to the process and can impact the performance of your application. Hence, we recommend using the [Logger](https://docs.adonisjs.com/guides/logger) to log the database queries during production.
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Following is a complete example of switching the event listener based upon the application environment.
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```ts
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// title: start/events.ts
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import db from '@adonisjs/lucid/services/db'
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import emitter from '@adonisjs/core/services/emitter'
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import logger from '@adonisjs/core/services/logger'
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import app from '@adonisjs/core/services/app'
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emitter.on('db:query', (query) => {
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if (app.inProduction) {
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logger.debug(query)
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} else {
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db.prettyPrint(query)
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}
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emitter.on('db:query', function (query) {
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logger.debug(query)
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})
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```

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