Picking

A pick is the warehouse instruction sheet created when a sales order is issued. It tells your team exactly which products to pull from inventory and in what quantities, driving the first stage of the fulfillment process.

How a pick is created

When you issue a sales order, OpenMRP automatically creates a pick. The pick contains one line for every sale-type product on the order — freight, discount, and other system lines are never picked. Each pick line points back at its order line for the quantity ordered and starts at zero picked; the worker fills that in as stock comes off the shelf. The pick number matches the sales order number, so warehouse staff can easily cross-reference the two.

On the factory floor

The typical picking workflow looks like this:

1. A warehouse worker receives the pick sheet (printed or on a mobile device)
2. They walk the warehouse, locating each product and pulling the required quantity
3. As items are pulled, the worker records the quantity picked against each line
4. Once all lines are addressed, the picked items move to the packing station

Pick lines and quantities

Each pick line tracks two key values:

• Quantity ordered: the amount requested by the sales order
• Quantity picked: the amount actually pulled from the shelf

The relationship between these two values drives the pick's progress and determines whether any reconciliation is needed at packing.

Over-picks and under-picks

OpenMRP allows both over-picks and under-picks: the system does not block either scenario:

• Over-pick: the worker pulled more than the order requested. This can happen when an extra unit is found in the bin or a partial case must be pulled whole. The surplus is reconciled during packing.
• Under-pick: the worker pulled less than ordered. This typically occurs when stock is short or items are damaged. The shortfall is handled during packing, where partial packing lets you ship what's available now and fulfill the rest later.

This flexibility keeps the warehouse moving without forcing workers to stop and resolve discrepancies before they can proceed.

Pick completion

A pick carries no progress percentage of its own. Each pick line records the quantity picked against the ordered_quantity it was created for, and the pick's finished_at timestamp is stamped automatically once every line on the pick has been packed — which happens at packing, not at picking. Recording a pick quantity on every line does not by itself finish the pick; it just means the picked items are ready to move to the packing station.

For a rollup across the whole order, read the sales order's totals.picked instead: it carries the picked amount and a completion fraction between 0 and 1, measured as picked quantity over ordered quantity.

When the order changes after issue

Editing an issued order's lines does not leave the pick alone. OpenMRP silently rewrites it so the warehouse instruction always matches what is still owed, and the rules are worth knowing before you edit a live order.

Reconciliation runs off a single number, computed per order line:

outstanding = quantity ordered − quantity already packed

• While outstanding is greater than zero there is still work to do. OpenMRP makes sure exactly one open (unpacked) pick line exists to hold it, seeded at zero picked — not at the remaining amount, so a line added to an order that was already picked does not read as though someone has picked it — and it clears the pick's finished timestamp, reopening the pick.
• Once packed covers the order — outstanding is zero or negative, which happens when you reduce a quantity back down — any leftover open pick line is deleted, and the pick is marked finished if every line that remains is packed.

This applies to adding a line, and to any update of an existing line on an order that already has a pick — not just a quantity change. A price-only or description-only edit runs the same reconciliation, so editing the price of a line that still has quantity outstanding clears the pick's finished timestamp and reopens the pick. It applies only to sale-type product lines: the automatically generated freight and discount lines are never picked, so touching one never seeds or removes a pick line.

Closing the order also closes the pick — every still-open pick line is packed and the pick is stamped finished. Reopening the order reverses it: the pick's finished timestamp is cleared and every line that is not yet fully picked is reopened, while fully picked lines stay packed.

Deleting the last line reverts the order to an estimate

This one is destructive and easy to trip over. Deleting a line removes that line's pick lines along with it. If the pick has no lines left afterwards, OpenMRP concludes the order has nothing to fulfill and tears the whole thing down in one transaction:

1. The pick is deleted — along with any picking progress recorded on it.
2. The order's reserved inventory issues and their allocations are deleted, releasing the reserved inventory back to stock.
3. The order's status reverts from issued to estimate.

In other words, removing the last line of an issued order performs the same teardown as unissuing it, as a side effect of what looks like an ordinary line edit. If you meant to swap the last product on an order, add the replacement line first, then delete the old one — that keeps the pick alive and preserves the inventory reservation.

Deleting a line is blocked outright once that line has a shipment against it, or once the order is fulfilled. On an order that has been completed or that has any shipped shipment, deleting a line requires an admin.

Voiding a pick

A pick can be voided as long as no items from the pick have been shipped. Voiding a pick:

• Voids all pick lines
• Reopens the pick for re-picking if needed

This is useful when an order changes after picking has started but before anything has left the building.

Next steps

Once picking is complete, move to packing to pack the picked items into shipping cases and create shipments.

Next: Packing