3fefc2b284
When loading a derivation from a JSON, malformed input would trigger
cryptic "assertion failed" errors. Simply replacing calls to `operator []`
with calls to `.at()` was not enough, as this would cause json.execptions
to be printed verbatim.
Display nice error messages instead and give some indication where the
error happened.
*Before:*
```
$ echo 4 | nix derivation add
error: [json.exception.type_error.305] cannot use operator[] with a string argument with number
$ nix derivation show nixpkgs#hello | nix derivation add
Assertion failed: (it != m_value.object->end()), function operator[], file /nix/store/8h9pxgq1776ns6qi5arx08ifgnhmgl22-nlohmann_json-3.11.2/include/nlohmann/json.hpp, line 2135.
$ nix derivation show nixpkgs#hello | jq '.[] | .name = 5' | nix derivation add
error: [json.exception.type_error.302] type must be string, but is object
$ nix derivation show nixpkgs#hello | jq '.[] | .outputs = { out: "/nix/store/8j3f8j-hello" }' | nix derivation add
error: [json.exception.type_error.302] type must be object, but is string
```
*After:*
```
$ echo 4 | nix derivation add
error: Expected JSON of derivation to be of type 'object', but it is of type 'number'
$ nix derivation show nixpkgs#hello | nix derivation add
error: Expected JSON object to contain key 'name' but it doesn't
$ nix derivation show nixpkgs#hello | jq '.[] | .name = 5' | nix derivation add
error: Expected JSON value to be of type 'string' but it is of type 'number'
$ nix derivation show nixpkgs#hello | jq '.[] | .outputs = { out: "/nix/store/8j3f8j-hello" }' | nix derivation add
error:
… while reading key 'outputs'
error: Expected JSON value to be of type 'object' but it is of type 'string'
```
44 lines
988 B
C++
44 lines
988 B
C++
#include "json-utils.hh"
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#include "error.hh"
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namespace nix {
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const nlohmann::json * get(const nlohmann::json & map, const std::string & key)
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{
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auto i = map.find(key);
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if (i == map.end()) return nullptr;
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return &*i;
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}
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nlohmann::json * get(nlohmann::json & map, const std::string & key)
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{
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auto i = map.find(key);
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if (i == map.end()) return nullptr;
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return &*i;
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}
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const nlohmann::json & valueAt(
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const nlohmann::json & map,
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const std::string & key)
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{
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if (!map.contains(key))
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throw Error("Expected JSON object to contain key '%s' but it doesn't", key);
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return map[key];
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}
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const nlohmann::json & ensureType(
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const nlohmann::json & value,
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nlohmann::json::value_type expectedType
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)
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{
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if (value.type() != expectedType)
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throw Error(
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"Expected JSON value to be of type '%s' but it is of type '%s'",
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nlohmann::json(expectedType).type_name(),
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value.type_name());
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return value;
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}
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}
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