Couchbase Playground

CB Lite C - Query Documents

Developers using Couchbase Lite for C can provide SQL++ query strings using the SQL++ Query API. This API uses query statements of the form shown in the example. The structure and semantics of the query format are based on that of Couchbase Server's SQL++ query language.

This example parses the individual properties of the documents in the result.

See more at the CB Lite C SDK documentation on Querying.

To run this example, click the button in the top right corner of the code editor.

Code Editor

#include <cbl/CouchbaseLite.h>
#include <time.h>
#include <inttypes.h>
#include <unistd.h>

int main(int argc, char** argv) {

  // Get the database (and create it if it doesn't exist)
  CBLError err;
  CBLDatabase* database = CBLDatabase_Open(FLSTR("mydb"), NULL, &err);
  if(!database) {
      // Error handling.  For brevity, this is truncated in the rest of the snippet
      // and omitted in other doc code snippets
      fprintf(stderr, "Error opening database (%d / %d)\n", err.domain, err.code);
      FLSliceResult msg = CBLError_Message(&err);
      fprintf(stderr, "%.*s\n", (int)msg.size, (const char *)msg.buf);
      FLSliceResult_Release(msg);
      return 1;
  }

  // Create new documents (i.e. a record) in the database
  CBLDocument* mutableDoc1 = CBLDocument_Create();

  FLMutableDict properties1 = CBLDocument_MutableProperties(mutableDoc1);
  FLMutableDict_SetFloat(properties1, FLSTR("version"), 3.0f);
  FLMutableDict_SetString(properties1, FLSTR("type"), FLSTR("SDK"));
  FLMutableDict_SetString(properties1, FLSTR("language"), FLSTR("C"));

  CBLDocument* mutableDoc2 = CBLDocument_Create();

  FLMutableDict properties2 = CBLDocument_MutableProperties(mutableDoc2);
  FLMutableDict_SetFloat(properties2, FLSTR("version"), 2.0f);
  FLMutableDict_SetString(properties2, FLSTR("type"), FLSTR("SDK"));
  FLMutableDict_SetString(properties2, FLSTR("language"), FLSTR("Java"));

  // Save it to the database
  if(!CBLDatabase_SaveDocument(database, mutableDoc1, &err)) {
      // Failed to save, do error handling as above
      return 1;
  }

  if(!CBLDatabase_SaveDocument(database, mutableDoc2, &err)) {
      // Failed to save, do error handling as above
      return 1;
  }
  CBLDocument_Release(mutableDoc1);
  CBLDocument_Release(mutableDoc2);

  int errorPos;
  CBLQuery* query = CBLDatabase_CreateQuery(database, kCBLN1QLLanguage, FLSTR("SELECT * FROM mydb WHERE type = \"SDK\""), &errorPos, &err);
  if(!query) {
      // Failed to create query, do error handling as above
      // Note that errorPos will contain the position in the N1QL string
      // that the parse failed, if applicable
      return 1;
  }

  CBLResultSet* results = CBLQuery_Execute(query, &err);
  if(!results) {
      // Failed to run query, do error handling as above
      return 1;
  }
  
printf("Query Results\n");
while(CBLResultSet_Next(results)) {
      printf("-----\n");
      FLDict dict = FLValue_AsDict(CBLResultSet_ValueForKey(results, FLSTR("mydb")));

      FLString type = FLValue_AsString(FLDict_Get(dict, FLSTR("type")));
      FLString language = FLValue_AsString(FLDict_Get(dict, FLSTR("language")));
      float version = FLValue_AsFloat(FLDict_Get(dict, FLSTR("version")));

      printf("Type = %.*s\n", (int)type.size, (const char *)type.buf);
      printf("Language = %.*s\n", (int)language.size, (const char *)language.buf);
      printf("Version = %f\n", version);
  }
  CBLResultSet_Release(results);

  // Close database. No error handling for brevity
  CBLDatabase_Close(database, &err);
  
  // Release resources
  CBLQuery_Release(query);
  CBLDatabase_Release(database);

  return 0;

}

CB Lite C - Query Documents

Code Editor

Output