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(C) Check if Integer Exists at JSON PathDemonstrates how to get an integer value at a JSON path, and how to check to see if it exists.
#include <C_CkJsonObject.h> void ChilkatSample(void) { HCkJsonObject json; BOOL success; const char *path; int val; BOOL wasFound; json = CkJsonObject_Create(); // First build simple JSON.. CkJsonObject_UpdateInt(json,"test.abc",100); CkJsonObject_putEmitCompact(json,FALSE); printf("%s\n",CkJsonObject_emit(json)); // This is our JSON: // { // "test": { // "abc": 100, // } // } path = "test.notHere"; // The call to IntOf will return 0, because it's not present. // But how do we know if it really was present, and the value was truly 0? val = CkJsonObject_IntOf(json,path); printf("val = %d\n",val); // We cannot use LastMethodSuccess because LastMethodSuccess only applies // to methods that: // - return a string // - return a new Chilkat object, binary bytes, or a date/time. // - returns a boolean status where TRUE = success and FALSE = failed. // - returns an integer where failure is defined by a return value less than zero. // The IntOf method fits none of these requirements, and therefore the LastMethodSuccess // is not a valid indicator.. wasFound = CkJsonObject_getLastMethodSuccess(json); printf("wasFound = %d (not a valid indicator)\n",wasFound); // Instead, if the returned value is 0, we can double-check to see if the member was truly there.. if (val == 0) { wasFound = CkJsonObject_HasMember(json,path); printf("wasFound = %d\n",wasFound); if (wasFound == TRUE) { printf("The value was present and is 0.\n"); } else { printf("no member is present at test.notHere\n"); } } else { printf("val = %d\n",val); } // Alternatively, you could check to see if the member exists beforehand.. if (CkJsonObject_HasMember(json,path) == TRUE) { printf("val = %d\n",CkJsonObject_IntOf(json,path)); } else { printf("no member at %s\n",path); } CkJsonObject_Dispose(json); } |
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