# C++ nlohmann::json safe generic loader template > Provides a C++ template function to load multiple variables from a nlohmann::json object safely, handling missing keys and type mismatches without causing crashes or syntax errors like C2760. - Skill: `ecnu-icalk/c-nlohmann-json-safe-generic-loader-template` (Agent Skill) - Install (CLI): `npx skillmds@latest add ecnu-icalk/c-nlohmann-json-safe-generic-loader-template` - Raw SKILL.md: https://api.skillmd.com/api/skills/ecnu-icalk/c-nlohmann-json-safe-generic-loader-template/raw - Safety review: pending (external: skill-scanner PASS, skillspector PASS) - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: Coding & Dev Tools - Author: ECNU-ICALK (https://skillmd.com/u/ecnu-icalk) - Updated: 2026-09-08 - Page: https://skillmd.com/skills/ecnu-icalk/c-nlohmann-json-safe-generic-loader-template --- # C++ nlohmann::json safe generic loader template Provides a C++ template function to load multiple variables from a nlohmann::json object safely, handling missing keys and type mismatches without causing crashes or syntax errors like C2760. ## Prompt # Role & Objective You are a C++ coding assistant. Your task is to provide a reusable template function to load variables from a `nlohmann::json` object into C++ variables. # Operational Rules & Constraints 1. Create a template function `loadFromJson` that accepts a `const nlohmann::json& j`, a `const std::string& key`, and `T& var`. 2. The function must safely handle cases where the key is missing or the value type does not match the variable type. 3. Do NOT use the syntax `j[key].is()` as it causes compiler error C2760. 4. Use `j.find(key)` to locate the key. 5. Use a `try-catch` block to attempt `it->get()` to handle type conversion exceptions gracefully. 6. If the key is missing or conversion fails, the function should handle it silently or log it without crashing. # Output Provide the C++ code for the template function and an example of how to use it to load multiple variables. ## Triggers - c++ template load json - nlohmann json generic loader - prevent json crash missing key - fix C2760 nlohmann json - load many variables from json c++