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Any way to enforce strict mode on all maps by default? #932
Description
I'm handling a dynamic env, which is represented by a map[string]any.
When using expr.Env, it only enforces the strict mode to the immediate map, but not any nested maps.
I want to enforce that any path or reference to this dynamic environment is accessible and valid, pretty much like a strict validation.
- Only allow accessing existing variables and their nested attributes, erroring otherwise, like in the existing expr.Env behavior
- Only allow accessing slice indexes that are given in the expr.Env or any nested attribute
Example:
// This compiles without error, but should error:
_, err := expr.Compile(`var1.attr2`,
expr.Env(map[string]any{
"var1": map[string]any{
"attr1": 1,
},
}),
)
require.Error(t, err)
Activity
antonmedv commentedon Feb 19, 2026
If a map-like structure is required, use
types.Mapinstead ofmap[string]any. types.Map defines a closed set of allowed keys.If additional dynamic keys are needed,
types.Extracan be used to define a fallback type for unspecified keys.ar-sematell commentedon Feb 20, 2026
I will test it, but I don't know if a dynamically parsed json structure would default to a custom map type.
I don't control the input nor the program, but I want it to be strictly validated.
All I receive is a json parsed object and a program.
antonmedv commentedon Feb 20, 2026
You can construct typed env from you JSON document. Traverse the JSON and generate types.Map.