MegaHydronics•3d ago

Accessing database in an action

I'm hoping to better understand why ActionCtx does not expose db. This forces me to write much longer code like the first below, instead of the second.

export const set = internalAction({
  args: { key: v.string() },
  handler: async (ctx, { key }) => {
    const exists = await ctx.runQuery(internal.db.user._exists, { key })
    if (exists) return

    const response = await fetch(...)
    const args = await response.json()
    ctx.runMutation(internal.db.user._insert, args)
  },
})

export const _insert = internalMutation({
  args: v.object(userSchema),
  handler: async (ctx, args) => {
    await ctx.db.insert('user', args)
  },
})

export const _exists = internalQuery({
  args: { key: v.string() },
  handler: async (ctx, { key }) => {
    const user = await ctx.db.query('user').withIndex('key', q => q.eq('key', key)).unique()
    return user !== null
  },
})

export const set = internalAction({
  args: { key: v.string() },
  handler: async (ctx, { key }) => {
    const exists = await ctx.runQuery(internal.db.user._exists, { key })
    if (exists) return

    const response = await fetch(...)
    const args = await response.json()
    ctx.runMutation(internal.db.user._insert, args)
  },
})

export const _insert = internalMutation({
  args: v.object(userSchema),
  handler: async (ctx, args) => {
    await ctx.db.insert('user', args)
  },
})

export const _exists = internalQuery({
  args: { key: v.string() },
  handler: async (ctx, { key }) => {
    const user = await ctx.db.query('user').withIndex('key', q => q.eq('key', key)).unique()
    return user !== null
  },
})

export const set = internalAction({
  args: { key: v.string() },
  handler: async (ctx, { key }) => {
    const user = await ctx.db.query('user').withIndex('key', q => q.eq('key', key)).unique()
    if (user !== null) return

    const response = await fetch(...)
    const args = await response.json()
    await ctx.db.insert('user', args)
  },
})

export const set = internalAction({
  args: { key: v.string() },
  handler: async (ctx, { key }) => {
    const user = await ctx.db.query('user').withIndex('key', q => q.eq('key', key)).unique()
    if (user !== null) return

    const response = await fetch(...)
    const args = await response.json()
    await ctx.db.insert('user', args)
  },
})

2 Replies

Convex Bot•3d ago

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jamwt•3d ago

hi! queries and mutations need to be deterministic, and actions don't. we'd create race conditions and inconsistencies if we allowed access to the raw db object in actions. for most users, the results would be surprising and unintuitive. however. We do not love at all that it's so verbose to specify queries or mutations that only exist to service one particular action. we'd love to have a way to inline those to make things more ergonomic. but we haven't figured out how to do it yet, especially as it relates to like JavaScript semantics bundler behavior, etc. this is a long topic, but stuff like closures being allowed to mutate vars in the outer scope are particularly nasty and can make unpredictable program behavior