Struct odbc_api::Environment

pub struct Environment { /* fields omitted */ }

An ODBC 3.8 environment.

Associated with an Environment is any information that is global in nature, such as:

• The Environment’s state
• The current environment-level diagnostics
• The handles of connections currently allocated on the environment
• The current stetting of each environment attribute

Creating the environment is the first applications do, then interacting with an ODBC driver manager. There must only be one environment in the entire process.

Implementations

impl Environment

pub unsafe fn new() -> Result<Self, Error>

Entry point into this API. Allocates a new ODBC Environment and declares to the driver manager that the Application wants to use ODBC version 3.8.

Safety

There may only be one ODBC environment in any process at any time. Take care using this function in unit tests, as these run in parallel by default in Rust. Also no library should probably wrap the creation of an odbc environment into a safe function call. This is because using two of these “safe” libraries at the same time in different parts of your program may lead to race condition thus violating Rust’s safety guarantees.

Creating one environment in your binary is safe however.

pub fn connect(
    &self,
    data_source_name: &str,
    user: &str,
    pwd: &str
) -> Result<Connection<'_>, Error>

Allocates a connection handle and establishes connections to a driver and a data source.

• See Connecting with SQLConnect
• See SQLConnectFunction

Arguments

• data_source_name - Data source name. The data might be located on the same computer as the program, or on another computer somewhere on a network.
• user - User identifier.
• pwd - Authentication string (typically the password).

Example

use odbc_api::Environment;

// I herby solemnly swear that this is the only ODBC environment in the entire process, thus
// making this call safe.
let env = unsafe {
    Environment::new()?
};

let mut conn = env.connect("YourDatabase", "SA", "<YourStrong@Passw0rd>")?;

pub fn connect_utf16(
    &self,
    data_source_name: &U16Str,
    user: &U16Str,
    pwd: &U16Str
) -> Result<Connection<'_>, Error>

Allocates a connection handle and establishes connections to a driver and a data source.

• See Connecting with SQLConnect
• See SQLConnectFunction

Arguments

• data_source_name - Data source name. The data might be located on the same computer as the program, or on another computer somewhere on a network.
• user - User identifier.
• pwd - Authentication string (typically the password).

pub fn connect_with_connection_string(
    &self,
    connection_string: &str
) -> Result<Connection<'_>, Error>

Allocates a connection handle and establishes connections to a driver and a data source.

An alternative to connect. It supports data sources that require more connection information than the three arguments in connect and data sources that are not defined in the system information.

To find out your connection string try: https://www.connectionstrings.com/

Example

use odbc_api::Environment;

// I herby solemnly swear that this is the only ODBC environment in the entire process, thus
// making this call safe.
let env = unsafe {
    Environment::new()?
};

let connection_string = "
    Driver={ODBC Driver 17 for SQL Server};\
    Server=localhost;\
    UID=SA;\
    PWD=<YourStrong@Passw0rd>;\
";

let mut conn = env.connect_with_connection_string(connection_string)?;

pub fn connect_with_connection_string_utf16(
    &self,
    connection_string: &U16Str
) -> Result<Connection<'_>, Error>

Allocates a connection handle and establishes connections to a driver and a data source.

An alternative to connect. It supports data sources that require more connection information than the three arguments in connect and data sources that are not defined in the system information.

To find out your connection string try: https://www.connectionstrings.com/

pub fn driver_connect(
    &self,
    connection_string: &str,
    completed_connection_string: Option<&mut OutputStringBuffer>,
    driver_completion: DriverCompleteOption<'_>
) -> Result<Connection<'_>, Error>

Allocates a connection handle and establishes connections to a driver and a data source.

An alternative to connect and connect_with_connection_string. This method can be provided with an incomplete or even empty connection string. If any additional information is required, the driver manager/driver will attempt to create a prompt to allow the user to provide the additional information.

If the connection is successful, the complete connection string (including any information provided by the user through a prompt) is returned.

Parameters

• connection_string: Connection string.
• completed_connection_string: Output buffer with the complete connection string. It is recommended to choose a buffer with at least 1024 bytes length.
• driver_completion: Specifies how and if the driver manager uses a prompt to complete the provided connection string.

Examples

In the first example, we intentionally provide a blank connection string so the user will be prompted to select a data source to use. Note that this functionality is only available on windows.

use odbc_api::{Environment, handles::OutputStringBuffer, DriverCompleteOption};

// I hereby solemnly swear that this is the only ODBC environment in the entire process,
// thus making this call safe.
let env = unsafe {
    Environment::new()?
};

let mut output_buffer = OutputStringBuffer::with_buffer_size(1024);
let connection = env.driver_connect(
    "",
    Some(&mut output_buffer),
    DriverCompleteOption::Prompt(&parent_window),
)?;

// Check that the output buffer has been large enough to hold the entire connection string.
assert!(!output_buffer.is_truncated());

// Now `connection_string` will contain the data source selected by the user.
let connection_string = output_buffer.to_utf8();

In the following examples we specify a DSN that requires login credentials, but the DSN does not provide those credentials. Instead, the user will be prompted for a UID and PWD. The returned connection_string will contain the UID and PWD provided by the user. Note that this functionality is currently only available on windows targets.

let without_uid_or_pwd = "DSN=SomeSharedDatabase;";
let connection = env.driver_connect(
    &without_uid_or_pwd,
    Some(&mut output_buffer),
    DriverCompleteOption::Complete(&parent_window),
)?;
let connection_string = output_buffer.to_utf8();

// Now `connection_string` might be something like
// `DSN=SomeSharedDatabase;UID=SA;PWD=<YourStrong@Passw0rd>;`

In this case, we use a DSN that is already sufficient and does not require a prompt. Because a prompt is not needed, window is also not required. The returned connection_string will be mostly the same as already_sufficient but the driver may append some extra attributes.

let already_sufficient = "DSN=MicrosoftAccessFile;";
let connection = env.driver_connect(
   &already_sufficient,
   Some(&mut output_buffer),
   DriverCompleteOption::NoPrompt,
)?;
let connection_string = output_buffer.to_utf8();

// Now `connection_string` might be something like
// `DSN=MicrosoftAccessFile;DBQ=C:\Db\Example.accdb;DriverId=25;FIL=MS Access;MaxBufferSize=2048;`

pub fn drivers(&self) -> Result<Vec<DriverInfo>, Error>

Get information about available drivers. Only 32 or 64 Bit drivers will be listed, depending on wether you are building a 32 Bit or 64 Bit application.

Example

use odbc_api::Environment;

let env = unsafe { Environment::new () }?;
for driver_info in env.drivers()? {
    println!("{:#?}", driver_info);
}

pub fn data_sources(&self) -> Result<Vec<DataSourceInfo>, Error>

User and system data sources

Example

use odbc_api::Environment;

let env = unsafe { Environment::new () }?;
for data_source in env.data_sources()? {
    println!("{:#?}", data_source);
}

pub fn system_data_sources(&self) -> Result<Vec<DataSourceInfo>, Error>

Only system data sources

Example

use odbc_api::Environment;

let env = unsafe { Environment::new () }?;
for data_source in env.system_data_sources()? {
    println!("{:#?}", data_source);
}

pub fn user_data_sources(&self) -> Result<Vec<DataSourceInfo>, Error>

Only user data sources

Example

use odbc_api::Environment;

let mut env = unsafe { Environment::new () }?;
for data_source in env.user_data_sources()? {
    println!("{:#?}", data_source);
}