Special `expressions.Error` type for returing messages from `expressions.Cond` branches

Feature Requests Requests
1

here’s an example to demonstrate what i’m looking for

import aerospike
from aerospike_helpers import cdt_ctx, expressions
from aerospike_helpers.expressions.arithmetic import Add
from aerospike_helpers.operations import expression_operations

ac = aerospike.client({'hosts': [('localhost', 3000)]})
ac.connect()
key = ('test', 'test', 'test')
ac.remove(key)
ac.put(key, {'bin': {'vals': [], 'tokens': 1}})

def add_val_if_enough_tokens_and_empty(val):
    ac.operate(
        key,
        [
            expression_operations.expression_write(
                'bin',
                expressions.Cond(
                    expressions.GT(
                        expressions.MapGetByKey(
                            ctx=None,
                            return_type=aerospike.MAP_RETURN_VALUE,
                            value_type=expressions.resources.ResultType.INTEGER,
                            key='tokens',
                            bin=expressions.MapBin('bin')
                        ),
                        0
                    ),
                    expressions.Cond(
                        expressions.GT(
                            expressions.ListSize(
                                ctx=[cdt_ctx.cdt_ctx_map_key('vals')],
                                bin=expressions.MapBin('bin')
                            ),
                            0
                        ),
                        expressions.Unknown(),
                        expressions.ListAppend(
                            ctx=[cdt_ctx.cdt_ctx_map_key('vals')],
                            policy=None,
                            value=val,
                            bin=expressions.MapBin('bin')
                        )
                    ),
                    expressions.Unknown()
                ).compile(),
                # aerospike.EXP_WRITE_EVAL_NO_FAIL
                # aerospike.EXP_WRITE_POLICY_NO_FAIL
            )
        ]
    )

for _ in range(2):
    print(ac.get(key)[2])
    try:
        add_val_if_enough_tokens_and_empty('val')
    except aerospike.exception.OpNotApplicable as e:
        print(f'op failed because {e}')

with output

{'bin': {'vals': [], 'tokens': 1}}
{'bin': {'vals': ['val'], 'tokens': 1}}
op failed because (26, '127.0.0.1:3000 AEROSPIKE_ERR_OP_NOT_APPLICABLE', 'src/main/client/operate.c', 813, False)

so here, i want to only add a value to vals if tokens is greater than 0 and vals is empty, which is achieved with this, but i cannot transactionally know which one of them was not satisfied on failure (unless of course i fetch the record, which isn’t transactional), so would like to have something like this

import aerospike
from aerospike_helpers import cdt_ctx, expressions
from aerospike_helpers.operations import expression_operations

ac = aerospike.client({'hosts': [('localhost', 3000)]})
ac.connect()
key = ('test', 'test', 'test')
ac.remove(key)
ac.put(key, {'bin': {'vals': [], 'tokens': 1}})

def add_val_if_enough_tokens_and_empty(val):
    ac.operate(
        key,
        [
            expression_operations.expression_write(
                'bin',
                expressions.Cond(
                    expressions.GT(
                        expressions.MapGetByKey(
                            ctx=None,
                            return_type=aerospike.MAP_RETURN_VALUE,
                            value_type=expressions.resources.ResultType.INTEGER,
                            key='tokens',
                            bin=expressions.MapBin('bin')
                        ),
                        0
                    ),
                    expressions.Cond(
                        expressions.GT(
                            expressions.ListSize(
                                ctx=[cdt_ctx.cdt_ctx_map_key('vals')],
                                bin=expressions.MapBin('bin')
                            ),
                            0
                        ),
                        expressions.Error("vals isn't empty"),
                        expressions.ListAppend(
                            ctx=[cdt_ctx.cdt_ctx_map_key('vals')],
                            policy=None,
                            value=val,
                            bin=expressions.MapBin('bin')
                        )
                    ),
                    expressions.Error("no tokens")
                ).compile(),
                # aerospike.EXP_WRITE_EVAL_NO_FAIL
                # aerospike.EXP_WRITE_POLICY_NO_FAIL
            )
        ]
    )

for _ in range(2):
    print(ac.get(key)[2])
    try:
        add_val_if_enough_tokens_and_empty('val')
    except aerospike.exception.OpNotApplicable as e:
        print(f'op failed because {e}')

with the expressions.Error’s which would be parsable from the resulting aerospike.exception.OpNotApplicable or some other error type specifically for this sorta thing

does this feature make sense?

2

Thanks for your suggestion. Let me pass this to our Product folks.

3

This is apparently not possible the way the code is currently structured but could be considered in the future. I have filed a formal product feature request internally (PROD-2118 – only for reference).

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