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(Unicode C) Using Pre-defined JSON TemplatesDemonstrates how to predefine a JSON template, and then use it to emit JSON with variable substitutions. Note: This example requires Chilkat v9.5.0.67 or greater.
#include <C_CkJsonObjectW.h> #include <C_CkHashtableW.h> void ChilkatSample(void) { HCkJsonObjectW json; HCkJsonObjectW jsonTemplate; HCkJsonObjectW jsonDonut; HCkHashtableW donutValues; BOOL omitEmpty; // One way to create JSON is to do it in a straightforward manner: json = CkJsonObjectW_Create(); CkJsonObjectW_putEmitCompact(json,FALSE); CkJsonObjectW_UpdateString(json,L"id",L"0001"); CkJsonObjectW_UpdateString(json,L"type",L"donut"); CkJsonObjectW_UpdateString(json,L"name",L"Cake"); CkJsonObjectW_UpdateString(json,L"image.url",L"images/0001.jpg"); CkJsonObjectW_UpdateInt(json,L"image.width",200); CkJsonObjectW_UpdateInt(json,L"image.height",200); CkJsonObjectW_UpdateString(json,L"thumbnail.url",L"images/thumbnails/0001.jpg"); CkJsonObjectW_UpdateInt(json,L"thumbnail.width",32); CkJsonObjectW_UpdateInt(json,L"thumbnail.height",32); wprintf(L"%s\n",CkJsonObjectW_emit(json)); // The JSON created by the above code: // { // "id": "0001", // "type": "donut", // "name": "Cake", // "image": { // "url": "images/0001.jpg", // "width": 200, // "height": 200 // }, // "thumbnail": { // "url": "images/thumbnails/0001.jpg", // "width": 32, // "height": 32 // } // } // An alternative is to predefine a template, and then use it to emit with variable substitutions. // For example: jsonTemplate = CkJsonObjectW_Create(); CkJsonObjectW_UpdateString(jsonTemplate,L"id",L"{$id}"); CkJsonObjectW_UpdateString(jsonTemplate,L"type",L"donut"); CkJsonObjectW_UpdateString(jsonTemplate,L"name",L"{$name}"); CkJsonObjectW_UpdateString(jsonTemplate,L"image.url",L"{$imageUrl}"); // The "i." indicates that it's an integer variable. CkJsonObjectW_UpdateString(jsonTemplate,L"image.width",L"{$i.imageWidth}"); CkJsonObjectW_UpdateString(jsonTemplate,L"image.height",L"{$i.imageHeight}"); CkJsonObjectW_UpdateString(jsonTemplate,L"thumbnail.url",L"{$thumbUrl}"); CkJsonObjectW_UpdateString(jsonTemplate,L"thumbnail.width",L"{$i.thumbWidth}"); CkJsonObjectW_UpdateString(jsonTemplate,L"thumbnail.height",L"{$i.thumbHeight}"); // Give this template a name. CkJsonObjectW_Predefine(jsonTemplate,L"donut"); // -------------------------------------------------------------------------- // OK, the template is defined. Defining a template can be done once // at the start of your program, and you can discard the jsonTemplate object (it // doesn't need to stick around..) // Now we can create instances of the JSON object by name: jsonDonut = CkJsonObjectW_Create(); CkJsonObjectW_putEmitCompact(jsonDonut,FALSE); CkJsonObjectW_LoadPredefined(jsonDonut,L"donut"); wprintf(L"%s\n",CkJsonObjectW_emit(jsonDonut)); // The output is this: // { // "id": "{$id}", // "type": "donut", // "name": "{$name}", // "image": { // "url": "{$imageUrl}", // "width": "{$i.imageWidth}", // "height": "{$i.imageHeight}" // }, // "thumbnail": { // "url": "{$thumbUrl}", // "width": "{$i.thumbWidth}", // "height": "{$i.thumbHeight}" // } // } // Finally, we can substitute variables like this: donutValues = CkHashtableW_Create(); CkHashtableW_AddStr(donutValues,L"id",L"0001"); CkHashtableW_AddStr(donutValues,L"name",L"Cake"); CkHashtableW_AddStr(donutValues,L"imageUrl",L"images/0001.jpg"); CkHashtableW_AddInt(donutValues,L"imageWidth",200); CkHashtableW_AddInt(donutValues,L"imageHeight",200); CkHashtableW_AddStr(donutValues,L"thumbUrl",L"images/thumbnails/0001.jpg"); CkHashtableW_AddInt(donutValues,L"thumbWidth",32); CkHashtableW_AddInt(donutValues,L"thumbHeight",32); // Emit with variable substitutions: omitEmpty = TRUE; wprintf(L"%s\n",CkJsonObjectW_emitWithSubs(jsonDonut,donutValues,omitEmpty)); // Output: // { // "id": "0001", // "type": "donut", // "name": "Cake", // "image": { // "url": "images/0001.jpg", // "width": 200, // "height": 200 // }, // "thumbnail": { // "url": "images/thumbnails/0001.jpg", // "width": 32, // "height": 32 // } // } // Change some of the values: CkHashtableW_AddStr(donutValues,L"id",L"0002"); CkHashtableW_AddStr(donutValues,L"imageUrl",L"images/0002.jpg"); CkHashtableW_AddStr(donutValues,L"thumbUrl",L"images/thumbnails/0002.jpg"); wprintf(L"%s\n",CkJsonObjectW_emitWithSubs(jsonDonut,donutValues,omitEmpty)); // Output: // { // "id": "0002", // "type": "donut", // "name": "Cake", // "image": { // "url": "images/0002.jpg", // "width": 200, // "height": 200 // }, // "thumbnail": { // "url": "images/thumbnails/0002.jpg", // "width": 32, // "height": 32 // } // } CkJsonObjectW_Dispose(json); CkJsonObjectW_Dispose(jsonTemplate); CkJsonObjectW_Dispose(jsonDonut); CkHashtableW_Dispose(donutValues); } |
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