396 lines
10 KiB
Go
396 lines
10 KiB
Go
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package gorqlite
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import "errors"
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import "fmt"
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import "encoding/json"
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/* *****************************************************************
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method: Connection.Query()
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This is the JSON we get back:
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{
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"results": [
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{
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"columns": [
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"id",
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"name"
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],
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"types": [
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"integer",
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"text"
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],
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"values": [
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[
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1,
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"fiona"
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],
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[
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2,
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"sinead"
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]
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],
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"time": 0.0150043
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}
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],
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"time": 0.0220043
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}
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or
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{
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"results": [
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{
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"columns": [
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"id",
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"name"
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],
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"types": [
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"number",
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"text"
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],
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"values": [
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[
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null,
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"Hulk"
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]
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],
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"time": 4.8958e-05
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},
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{
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"columns": [
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"id",
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"name"
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],
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"types": [
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"number",
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"text"
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],
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"time": 1.8460000000000003e-05
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}
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],
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"time": 0.000134776
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}
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or
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{
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"results": [
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{
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"error": "near \"nonsense\": syntax error"
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}
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],
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"time": 2.478862
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}
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* *****************************************************************/
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/*
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QueryOne() is a convenience method that wraps Query() into a single-statement
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method.
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*/
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func (conn *Connection) QueryOne(sqlStatement string) (qr QueryResult, err error) {
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if conn.hasBeenClosed {
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qr.Err = errClosed
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return qr, errClosed
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}
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sqlStatements := make([]string, 0)
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sqlStatements = append(sqlStatements, sqlStatement)
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qra, err := conn.Query(sqlStatements)
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return qra[0], err
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}
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/*
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Query() is used to perform SELECT operations in the database.
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It takes an array of SQL statements and executes them in a single transaction, returning an array of QueryResult vars.
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*/
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func (conn *Connection) Query(sqlStatements []string) (results []QueryResult, err error) {
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results = make([]QueryResult, 0)
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if conn.hasBeenClosed {
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var errResult QueryResult
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errResult.Err = errClosed
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results = append(results, errResult)
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return results, errClosed
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}
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trace("%s: Query() for %d statements", conn.ID, len(sqlStatements))
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// if we get an error POSTing, that's a showstopper
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response, err := conn.rqliteApiPost(api_QUERY, sqlStatements)
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if err != nil {
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trace("%s: rqliteApiCall() ERROR: %s", conn.ID, err.Error())
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var errResult QueryResult
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errResult.Err = err
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results = append(results, errResult)
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return results, err
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}
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trace("%s: rqliteApiCall() OK", conn.ID)
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// if we get an error Unmarshaling, that's a showstopper
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var sections map[string]interface{}
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err = json.Unmarshal(response, §ions)
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if err != nil {
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trace("%s: json.Unmarshal() ERROR: %s", conn.ID, err.Error())
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var errResult QueryResult
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errResult.Err = err
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results = append(results, errResult)
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return results, err
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}
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/*
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at this point, we have a "results" section and
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a "time" section. we can igore the latter.
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*/
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resultsArray := sections["results"].([]interface{})
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trace("%s: I have %d result(s) to parse", conn.ID, len(resultsArray))
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numStatementErrors := 0
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for n, r := range resultsArray {
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trace("%s: parsing result %d", conn.ID, n)
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var thisQR QueryResult
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thisQR.conn = conn
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// r is a hash with columns, types, values, and time
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thisResult := r.(map[string]interface{})
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// did we get an error?
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_, ok := thisResult["error"]
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if ok {
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trace("%s: have an error on this result: %s", conn.ID, thisResult["error"].(string))
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thisQR.Err = errors.New(thisResult["error"].(string))
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results = append(results, thisQR)
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numStatementErrors++
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continue
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}
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// time is a float64
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thisQR.Timing = thisResult["time"].(float64)
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// column & type are an array of strings
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c := thisResult["columns"].([]interface{})
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t := thisResult["types"].([]interface{})
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for i := 0; i < len(c); i++ {
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thisQR.columns = append(thisQR.columns, c[i].(string))
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thisQR.types = append(thisQR.types, t[i].(string))
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}
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// and values are an array of arrays
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if thisResult["values"] != nil {
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thisQR.values = thisResult["values"].([]interface{})
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} else {
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trace("%s: fyi, no values this query", conn.ID)
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}
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thisQR.rowNumber = -1
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trace("%s: this result (#col,time) %d %f", conn.ID, len(thisQR.columns), thisQR.Timing)
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results = append(results, thisQR)
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}
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trace("%s: finished parsing, returning %d results", conn.ID, len(results))
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if numStatementErrors > 0 {
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return results, errors.New(fmt.Sprintf("there were %d statement errors", numStatementErrors))
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} else {
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return results, nil
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}
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}
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/* *****************************************************************
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type: QueryResult
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* *****************************************************************/
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/*
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A QueryResult type holds the results of a call to Query(). You could think of it as a rowset.
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So if you were to query:
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SELECT id, name FROM some_table;
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then a QueryResult would hold any errors from that query, a list of columns and types, and the actual row values.
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Query() returns an array of QueryResult vars, while QueryOne() returns a single variable.
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*/
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type QueryResult struct {
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conn *Connection
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Err error
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columns []string
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types []string
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Timing float64
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values []interface{}
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rowNumber int64
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}
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// these are done as getters rather than as public
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// variables to prevent monkey business by the user
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// that would put us in an inconsistent state
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/* *****************************************************************
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method: QueryResult.Columns()
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* *****************************************************************/
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/*
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Columns returns a list of the column names for this QueryResult.
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*/
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func (qr *QueryResult) Columns() []string {
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return qr.columns
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}
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/* *****************************************************************
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method: QueryResult.Map()
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* *****************************************************************/
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/*
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Map() returns the current row (as advanced by Next()) as a map[string]interface{}
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The key is a string corresponding to a column name.
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The value is the corresponding column.
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Note that only json values are supported, so you will need to type the interface{} accordingly.
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*/
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func (qr *QueryResult) Map() (map[string]interface{}, error) {
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trace("%s: Map() called for row %d", qr.conn.ID, qr.rowNumber)
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ans := make(map[string]interface{})
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if qr.rowNumber == -1 {
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return ans, errors.New("you need to Next() before you Map(), sorry, it's complicated")
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}
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thisRowValues := qr.values[qr.rowNumber].([]interface{})
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for i := 0; i < len(qr.columns); i++ {
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ans[qr.columns[i]] = thisRowValues[i]
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}
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return ans, nil
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}
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/* *****************************************************************
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method: QueryResult.Next()
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* *****************************************************************/
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/*
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Next() positions the QueryResult result pointer so that Scan() or Map() is ready.
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You should call Next() first, but gorqlite will fix it if you call Map() or Scan() before
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the initial Next().
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A common idiom:
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rows := conn.Write(something)
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for rows.Next() {
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// your Scan/Map and processing here.
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}
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*/
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func (qr *QueryResult) Next() bool {
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if qr.rowNumber >= int64(len(qr.values)-1) {
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return false
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}
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qr.rowNumber += 1
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return true
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}
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/* *****************************************************************
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method: QueryResult.NumRows()
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* *****************************************************************/
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/*
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NumRows() returns the number of rows returned by the query.
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*/
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func (qr *QueryResult) NumRows() int64 {
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return int64(len(qr.values))
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}
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/* *****************************************************************
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method: QueryResult.RowNumber()
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* *****************************************************************/
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/*
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RowNumber() returns the current row number as Next() iterates through the result's rows.
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*/
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func (qr *QueryResult) RowNumber() int64 {
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return qr.rowNumber
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}
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/* *****************************************************************
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method: QueryResult.Scan()
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* *****************************************************************/
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/*
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Scan() takes a list of pointers and then updates them to reflect he current row's data.
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Note that only the following data types are used, and they
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are a subset of the types JSON uses:
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string, for JSON strings
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float64, for JSON numbers
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int64, as a convenient extension
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nil for JSON null
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booleans, JSON arrays, and JSON objects are not supported,
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since sqlite does not support them.
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*/
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func (qr *QueryResult) Scan(dest ...interface{}) error {
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trace("%s: Scan() called for %d vars", qr.conn.ID, len(dest))
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if qr.rowNumber == -1 {
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return errors.New("you need to Next() before you Scan(), sorry, it's complicated")
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}
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if len(dest) != len(qr.columns) {
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return errors.New(fmt.Sprintf("expected %d columns but got %d vars\n", len(qr.columns), len(dest)))
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}
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thisRowValues := qr.values[qr.rowNumber].([]interface{})
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for n, d := range dest {
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switch d.(type) {
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case *int64:
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f := int64(thisRowValues[n].(float64))
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*d.(*int64) = f
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case *float64:
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f := float64(thisRowValues[n].(float64))
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*d.(*float64) = f
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case *string:
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s := string(thisRowValues[n].(string))
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*d.(*string) = s
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default:
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return errors.New(fmt.Sprintf("unknown destination type to scan into in variable #%d", n))
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}
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}
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return nil
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}
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/* *****************************************************************
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method: QueryResult.Types()
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* *****************************************************************/
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/*
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Types() returns an array of the column's types.
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Note that sqlite will repeat the type you tell it, but in many cases, it's ignored. So you can initialize a column as CHAR(3) but it's really TEXT. See https://www.sqlite.org/datatype3.html
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This info may additionally conflict with the reality that your data is being JSON encoded/decoded.
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*/
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func (qr *QueryResult) Types() []string {
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return qr.types
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}
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