Laravel 中带有 withCount 的案例陈述

Question

How do I achieve this kind of query in Laravel?

Model::query()
        ->select('id')
        ->withCount(['relation_1', 'relation_2', 'relation_3'])
        ->selectRaw(
            '(CASE
WHEN relation_1_count < 0 THEN "relation 1 failed"
WHEN relation_1_count > 0 and relation_2_count < 0 THEN "relation 2 failed"
WHEN relation_1_count > 0 and relation_2_count > 0 and relation_3_count < 0 THEN "relation 3 failed"
ELSE "All relations passed"
END) AS model_status')
    ->get()

This gives the relation_1_count column that does not exist.

What is the proper approach for this kind of problem?

Answer 1

Your count queries are aliased subqueries so you can't use the alias directly. In MySQL however you can use the alias in another subquery eg:

Model::query()
    ->select('id')
    ->withCount(['relation_1', 'relation_2', 'relation_3'])
    ->selectRaw("CASE WHEN (SELECT relation_1_count) < 0 THEN 'relation 1 failed'
                      WHEN (SELECT relation_1_count) > 0 AND (SELECT relation_2_count) < 0 THEN 'relation 2 failed'
                      WHEN (SELECT relation_1_count) > 0 AND (SELECT relation_2_count) > 0 AND (SELECT relation_3_count) < 0 THEN 'relation 3 failed'
                 ELSE 'All relations passed' END AS model_status")
->get()

though in my opinion this sort of logic to craft a presentational message is best handled by the PHP view logic.

Sidenote: I've not actually tried this particular one myself so let me know if it works.