| // Copyright 2012 The Chromium Authors |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef SQL_STATEMENT_H_ |
| #define SQL_STATEMENT_H_ |
| |
| #include <stdint.h> |
| |
| #include <string> |
| #include <vector> |
| |
| #include "base/component_export.h" |
| #include "base/containers/span.h" |
| #include "base/dcheck_is_on.h" |
| #include "base/memory/ref_counted.h" |
| #include "base/sequence_checker.h" |
| #include "base/strings/string_piece_forward.h" |
| #include "base/thread_annotations.h" |
| #include "base/time/time.h" |
| #include "sql/database.h" |
| |
| namespace sql { |
| |
| enum class SqliteResultCode : int; |
| |
| // Possible return values from ColumnType in a statement. These should match |
| // the values in sqlite3.h. |
| enum class ColumnType { |
| kInteger = 1, |
| kFloat = 2, |
| kText = 3, |
| kBlob = 4, |
| kNull = 5, |
| }; |
| |
| // Compiles and executes SQL statements. |
| // |
| // This class is not thread-safe. An instance must be accessed from a single |
| // sequence. This is enforced in DCHECK-enabled builds. |
| // |
| // Normal usage: |
| // sql::Statement s(connection_.GetUniqueStatement(...)); |
| // s.BindInt(0, a); |
| // if (s.Step()) |
| // return s.ColumnString(0); |
| // |
| // If there are errors getting the statement, the statement will be inert; no |
| // mutating or database-access methods will work. If you need to check for |
| // validity, use: |
| // if (!s.is_valid()) |
| // return false; |
| // |
| // Step() and Run() just return true to signal success. If you want to handle |
| // specific errors such as database corruption, install an error handler in |
| // in the connection object using set_error_delegate(). |
| class COMPONENT_EXPORT(SQL) Statement { |
| public: |
| // Creates an uninitialized statement. The statement will be invalid until |
| // you initialize it via Assign. |
| Statement(); |
| |
| explicit Statement(scoped_refptr<Database::StatementRef> ref); |
| |
| Statement(const Statement&) = delete; |
| Statement& operator=(const Statement&) = delete; |
| |
| Statement(Statement&&) = delete; |
| Statement& operator=(Statement&&) = delete; |
| |
| ~Statement(); |
| |
| // Initializes this object with the given statement, which may or may not |
| // be valid. Use is_valid() to check if it's OK. |
| void Assign(scoped_refptr<Database::StatementRef> ref); |
| |
| // Resets the statement to an uninitialized state corresponding to |
| // the default constructor, releasing the StatementRef. |
| void Clear(); |
| |
| // Returns true if the statement can be executed. All functions can still |
| // be used if the statement is invalid, but they will return failure or some |
| // default value. This is because the statement can become invalid in the |
| // middle of executing a command if there is a serious error and the database |
| // has to be reset. |
| bool is_valid() const { |
| DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_); |
| |
| return ref_->is_valid(); |
| } |
| |
| // Running ------------------------------------------------------------------- |
| |
| // Executes the statement, returning true on success. This is like Step but |
| // for when there is no output, like an INSERT statement. |
| bool Run(); |
| |
| // Executes the statement, returning true if there is a row of data returned. |
| // You can keep calling Step() until it returns false to iterate through all |
| // the rows in your result set. |
| // |
| // When Step returns false, the result is either that there is no more data |
| // or there is an error. This makes it most convenient for loop usage. If you |
| // need to disambiguate these cases, use Succeeded(). |
| // |
| // Typical example: |
| // while (s.Step()) { |
| // ... |
| // } |
| // return s.Succeeded(); |
| bool Step(); |
| |
| // Resets the statement to its initial condition. This includes any current |
| // result row, and also the bound variables if the |clear_bound_vars| is true. |
| void Reset(bool clear_bound_vars); |
| |
| // Returns true if the last executed thing in this statement succeeded. If |
| // there was no last executed thing or the statement is invalid, this will |
| // return false. |
| bool Succeeded() const; |
| |
| // Binding ------------------------------------------------------------------- |
| |
| // These all take a 0-based parameter index and return true on success. |
| // strings there may be out of memory. |
| void BindNull(int param_index); |
| void BindBool(int param_index, bool val); |
| void BindInt(int param_index, int val); |
| void BindInt(int param_index, |
| int64_t val) = delete; // Call BindInt64() instead. |
| void BindInt64(int param_index, int64_t val); |
| void BindDouble(int param_index, double val); |
| void BindCString(int param_index, const char* val); |
| void BindString(int param_index, base::StringPiece val); |
| |
| // If you need to store (potentially invalid) UTF-16 strings losslessly, |
| // store them as BLOBs instead. `BindBlob()` has an overload for this purpose. |
| void BindString16(int param_index, base::StringPiece16 value); |
| void BindBlob(int param_index, base::span<const uint8_t> value); |
| |
| // Overload that makes it easy to pass in std::string values. |
| void BindBlob(int param_index, base::span<const char> value) { |
| BindBlob(param_index, base::as_bytes(base::make_span(value))); |
| } |
| |
| // Overload that makes it easy to pass in std::u16string values. |
| void BindBlob(int param_index, base::span<const char16_t> value) { |
| BindBlob(param_index, base::as_bytes(base::make_span(value))); |
| } |
| |
| // Conforms with base::Time serialization recommendations. |
| // |
| // This is equivalent to the following snippets, which should be replaced. |
| // * BindInt64(col, val.ToInternalValue()) |
| // * BindInt64(col, val.ToDeltaSinceWindowsEpoch().InMicroseconds()) |
| // |
| // Features that serialize base::Time in other ways, such as ToTimeT() or |
| // ToJavaTime(), will require a database migration to be converted to this |
| // (recommended) serialization method. |
| // |
| // TODO(crbug.com/1195962): Migrate all time serialization to this method, and |
| // then remove the migration details above. |
| void BindTime(int param_index, base::Time time); |
| |
| // Conforms with base::TimeDelta serialization recommendations. |
| // |
| // This is equivalent to the following snippets, which should be replaced. |
| // * BindInt64(col, delta.ToInternalValue()) |
| // * BindInt64(col, delta.InMicroseconds()) |
| // |
| // TODO(crbug.com/1402777): Migrate all TimeDelta serialization to this method |
| // and remove the migration details above. |
| void BindTimeDelta(int param_index, base::TimeDelta delta); |
| |
| // Retrieving ---------------------------------------------------------------- |
| |
| // Returns the number of output columns in the result. |
| int ColumnCount() const; |
| |
| // Returns the type associated with the given column. |
| // |
| // Watch out: the type may be undefined if you've done something to cause a |
| // "type conversion." This means requesting the value of a column of a type |
| // where that type is not the native type. For safety, call ColumnType only |
| // on a column before getting the value out in any way. |
| ColumnType GetColumnType(int col); |
| |
| // These all take a 0-based argument index. |
| bool ColumnBool(int column_index); |
| int ColumnInt(int column_index); |
| int64_t ColumnInt64(int column_index); |
| double ColumnDouble(int column_index); |
| std::string ColumnString(int column_index); |
| |
| // If you need to store and retrieve (potentially invalid) UTF-16 strings |
| // losslessly, store them as BLOBs instead. They may be retrieved with |
| // `ColumnBlobAsString16()`. |
| std::u16string ColumnString16(int column_index); |
| |
| // Conforms with base::Time serialization recommendations. |
| // |
| // This is equivalent to the following snippets, which should be replaced. |
| // * base::Time::FromInternalValue(ColumnInt64(col)) |
| // * base::Time::FromDeltaSinceWindowsEpoch( |
| // base::Microseconds(ColumnInt64(col))) |
| // |
| // TODO(crbug.com/1195962): Migrate all time serialization to this method, and |
| // then remove the migration details above. |
| base::Time ColumnTime(int column_index); |
| |
| // Conforms with base::TimeDelta deserialization recommendations. |
| // |
| // This is equivalent to the following snippets, which should be replaced. |
| // * base::TimeDelta::FromInternalValue(ColumnInt64(column_index)) |
| // |
| // TODO(crbug.com/1402777): Migrate all TimeDelta serialization to this method |
| // and remove the migration details above. |
| base::TimeDelta ColumnTimeDelta(int column_index); |
| |
| // Returns a span pointing to a buffer containing the blob data. |
| // |
| // The span's contents should be copied to a caller-owned buffer immediately. |
| // Any method call on the Statement may invalidate the span. |
| // |
| // The span will be empty (and may have a null data) if the underlying blob is |
| // empty. Code that needs to distinguish between empty blobs and NULL should |
| // call GetColumnType() before calling ColumnBlob(). |
| base::span<const uint8_t> ColumnBlob(int column_index); |
| |
| bool ColumnBlobAsString(int column_index, std::string* result); |
| bool ColumnBlobAsString16(int column_index, std::u16string* result); |
| bool ColumnBlobAsVector(int column_index, std::vector<char>* result); |
| bool ColumnBlobAsVector(int column_index, std::vector<uint8_t>* result); |
| |
| // Diagnostics -------------------------------------------------------------- |
| |
| // Returns the original text of a SQL statement WITHOUT any bound values. |
| // Intended for logging in case of failures. Note that DOES NOT return any |
| // bound values, because that would cause a privacy / PII issue for logging. |
| std::string GetSQLStatement(); |
| |
| private: |
| friend class Database; |
| |
| // Checks SQLite result codes and handles any errors. |
| // |
| // Returns `sqlite_result_code`. This gives callers the convenience of writing |
| // "return CheckSqliteResultCode(sqlite_result_code)" and gives the compiler |
| // the opportunity of doing tail call optimization (TCO) on the code above. |
| // |
| // This method reports error codes to the associated Database, and updates |
| // internal state to reflect whether the statement succeeded or not. |
| SqliteResultCode CheckSqliteResultCode(SqliteResultCode sqlite_result_code); |
| |
| // Should be called by all mutating methods to check that the statement is |
| // valid. Returns true if the statement is valid. DCHECKS and returns false |
| // if it is not. |
| // The reason for this is to handle two specific cases in which a Statement |
| // may be invalid. The first case is that the programmer made an SQL error. |
| // Those cases need to be DCHECKed so that we are guaranteed to find them |
| // before release. The second case is that the computer has an error (probably |
| // out of disk space) which is prohibiting the correct operation of the |
| // database. Our testing apparatus should not exhibit this defect, but release |
| // situations may. Therefore, the code is handling disjoint situations in |
| // release and test. In test, we're ensuring correct SQL. In release, we're |
| // ensuring that contracts are honored in error edge cases. |
| bool CheckValid() const; |
| |
| // Helper for Run() and Step(), calls sqlite3_step() and returns the checked |
| // value from it. |
| SqliteResultCode StepInternal(); |
| |
| // The actual sqlite statement. This may be unique to us, or it may be cached |
| // by the Database, which is why it's ref-counted. This pointer is |
| // guaranteed non-null. |
| scoped_refptr<Database::StatementRef> ref_ |
| GUARDED_BY_CONTEXT(sequence_checker_); |
| |
| // See Succeeded() for what this holds. |
| bool succeeded_ GUARDED_BY_CONTEXT(sequence_checker_) = false; |
| |
| #if DCHECK_IS_ON() |
| // Used to DCHECK() that Bind*() is called before Step() or Run() are called. |
| bool step_called_ GUARDED_BY_CONTEXT(sequence_checker_) = false; |
| bool run_called_ GUARDED_BY_CONTEXT(sequence_checker_) = false; |
| #endif // DCHECK_IS_ON() |
| |
| SEQUENCE_CHECKER(sequence_checker_); |
| }; |
| |
| } // namespace sql |
| |
| #endif // SQL_STATEMENT_H_ |