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#2213 Refactor getConvertToStringSql* using a clearly defined interface
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The converstion itself was also slightly modified:
* Use an unbounded VARCHAR by default instead of setting the limit to
  255 chars, which has no clear basis.
* Optimise for Integers by limiting the VARCHAR length to 10 chars.
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@homedirectory
homedirectory committed Apr 10, 2024
1 parent e9c8823 commit 5945557
Showing 1 changed file with 121 additions and 72 deletions.
193 changes: 121 additions & 72 deletions ...rc/main/java/ua/com/fielden/platform/eql/stage3/operands/functions/AbstractFunction3.java
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Original file line number Diff line number Diff line change
@@ -1,16 +1,16 @@
package ua.com.fielden.platform.eql.stage3.operands.functions;

import static java.lang.String.format;

import java.util.Date;

import ua.com.fielden.platform.entity.query.DbVersion;
import ua.com.fielden.platform.eql.exceptions.EqlStage3ProcessingException;
import ua.com.fielden.platform.eql.meta.EqlDomainMetadata;
import ua.com.fielden.platform.eql.meta.PropType;
import ua.com.fielden.platform.eql.stage3.operands.AbstractSingleOperand3;
import ua.com.fielden.platform.eql.stage3.operands.ISingleOperand3;

import java.util.Date;

import static java.lang.String.format;

public abstract class AbstractFunction3 extends AbstractSingleOperand3 {

public AbstractFunction3(PropType type) {
Expand All @@ -23,83 +23,132 @@ public String sql(final EqlDomainMetadata metadata) {
}

protected String getConvertToStringSql(final EqlDomainMetadata metadata, final ISingleOperand3 operand) {
switch (metadata.dbVersion) {
case H2:
return getConvertToStringSqlForH2(metadata, operand);
case MSSQL:
return getConvertToStringSqlForMsSql2005(metadata, operand);
case POSTGRESQL:
return getConvertToStringSqlForPostgresql(metadata, operand);
case ORACLE:
return getConvertToStringSqlForOracle(metadata, operand);
default:
throw new EqlStage3ProcessingException("Function of converting value to string [" + getClass().getSimpleName() + "] is not yet implemented for RDBMS [" + metadata + "]!");
}
final IToStringConvertor converter = switch (metadata.dbVersion) {
case H2 -> ToStringConvertor.H2;
case MSSQL -> ToStringConvertor.MSSQL;
case POSTGRESQL -> ToStringConvertor.POSTGRESQL;
case ORACLE -> ToStringConvertor.ORACLE;
default -> throw new EqlStage3ProcessingException("Function of converting value to string [" + getClass().getSimpleName() + "] is not yet implemented for RDBMS [" + metadata + "]!");
};

return converter.convert(metadata, operand);
}

private String getConvertToStringSqlForOracle(final EqlDomainMetadata metadata, final ISingleOperand3 operand) {
if (Date.class.equals(operand.type().javaType())) {
return "TO_CHAR(" + operand.sql(metadata) + ", 'YYYY-MM-dd hh24:mm:ss')";
} else if (String.class.equals(operand.type().javaType())) {
return operand.sql(metadata);
} else {
return "CAST(" + operand.sql(metadata) + " AS VARCHAR2(255))";
/**
* A contract for converting an operand to an SQL expression of a string type.
*/
private interface IToStringConvertor {

/**
* Returns the DB version supported by this implementation.
*/
DbVersion dbVersion();

default String convert(final EqlDomainMetadata metadata, final ISingleOperand3 operand) {
if (operand.type().javaType() == String.class) {
return operand.sql(metadata);
} else if (operand.type().javaType() == Integer.class) {
return fromInteger(metadata, operand);
} else if (operand.type().javaType() == Date.class) {
return fromDate(metadata, operand);
} else {
return fromAny(metadata, operand);
}
}
}

private String getConvertToStringSqlForH2(final EqlDomainMetadata metadata, final ISingleOperand3 operand) {
if (Date.class.equals(operand.type().javaType())) {
return "FORMATDATETIME(" + operand.sql(metadata) + ", 'YYYY-MM-dd hh:mm:ss')";
} else if (String.class.equals(operand.type().javaType())) {
return operand.sql(metadata);
} else {
return "CAST(" + operand.sql(metadata) + " AS VARCHAR(255))";
default String fromInteger(final EqlDomainMetadata metadata, final ISingleOperand3 operand) {
// optimisation for integers: max integer value length is 10 chars
return dbVersion().castSql(operand.sql(metadata), "VARCHAR(10)");
}

default String fromDate(final EqlDomainMetadata metadata, final ISingleOperand3 operand) {
return fromAny(metadata, operand);
}
}

public static String getConvertToStringSqlForMsSql2005(final EqlDomainMetadata metadata, final ISingleOperand3 operand) {
if (Date.class.equals(operand.type().javaType())) {
// TODO The date/time format should be read from IDates, once this contract is extended to support domain-specific data formats.
// However, there needs to be a database-specific translation between formats.
final var opSql = operand.sql(metadata);
final var expression = "case " +
// TODO dd/MM/yyyy should really only be used for the case of @DateOnly or LocalDate once supported
"when DATEPART(hour, %s) = 0 and DATEPART(minute, %s) = 0 and DATEPART(second, %s) = 0 and DATEPART(millisecond, %s) = 0 then FORMAT(%s, 'dd/MM/yyyy') " +
"when DATEPART(second, %s) = 0 and DATEPART(millisecond, %s) = 0 then FORMAT(%s, 'dd/MM/yyyy HH:mm') " +
"when DATEPART(millisecond, %s) > 0 then FORMAT(%s, 'dd/MM/yyyy HH:mm:ss.fff') " +
"else FORMAT(%s, 'dd/MM/yyyy HH:mm:ss') end";
return expression.formatted(
opSql, opSql, opSql, opSql, opSql,
opSql, opSql, opSql,
opSql, opSql,
opSql);
} else if (String.class.equals(operand.type().javaType())) {
return operand.sql(metadata);
} else {
return "CAST(" + operand.sql(metadata) + " AS VARCHAR(255))";
default String fromAny(final EqlDomainMetadata metadata, final ISingleOperand3 operand) {
return dbVersion().castSql(operand.sql(metadata), "VARCHAR");
}

}

public static String getConvertToStringSqlForPostgresql(final EqlDomainMetadata metadata, final ISingleOperand3 operand) {
if (Date.class.equals(operand.type().javaType())) {
// TODO The date/time format should be read from IDates, once this contract is extended to support domain-specific data formats.
// However, there needs to be a database-specific translation between formats.
final var opSql = operand.sql(metadata);
final var expression = "case " +
// TODO DD/MM/YYYY should really only be used for the case of @DateOnly or LocalDate once supported
"when extract(milliseconds from %s \\:\\:timestamp) = 0 and extract(minutes from %s \\:\\:timestamp) = 0 and extract(hours from %s \\:\\:timestamp) = 0 then to_char(%s \\:\\:timestamp , 'DD/MM/YYYY') " +
"when extract(milliseconds from %s \\:\\:timestamp) = 0 then to_char(%s \\:\\:timestamp, 'DD/MM/YYYY HH24:MI') " +
"when cast(floor(extract(milliseconds from %s \\:\\:timestamp)) as integer) - 1000 * cast(floor(extract(seconds from %s \\:\\:timestamp)) as integer) > 0 then to_char(%s \\:\\:timestamp, 'DD/MM/YYYY HH24:MI:SS.MS') " +
"else to_char(%s \\:\\:timestamp, 'DD/MM/YYYY HH24:MI:SS') end";
return expression.formatted(
opSql, opSql, opSql, opSql,
opSql, opSql,
opSql, opSql, opSql,
opSql);
} else if (String.class.equals(operand.type().javaType())) {
return operand.sql(metadata);
} else {
return "CAST(" + operand.sql(metadata) + " AS VARCHAR(255))";
private enum ToStringConvertor implements IToStringConvertor {
H2 {
@Override
public DbVersion dbVersion() {
return DbVersion.H2;
}

@Override
public String fromDate(final EqlDomainMetadata metadata, final ISingleOperand3 operand) {
return "FORMATDATETIME(" + operand.sql(metadata) + ", 'YYYY-MM-dd hh:mm:ss')";
}
},

MSSQL {
@Override
public DbVersion dbVersion() {
return DbVersion.MSSQL;
}

@Override
public String fromDate(final EqlDomainMetadata metadata, final ISingleOperand3 operand) {
// TODO The date/time format should be read from IDates, once this contract is extended to support domain-specific data formats.
// However, there needs to be a database-specific translation between formats.
final var opSql = operand.sql(metadata);
final var expression = "case " +
// TODO dd/MM/yyyy should really only be used for the case of @DateOnly or LocalDate once supported
"when DATEPART(hour, %s) = 0 and DATEPART(minute, %s) = 0 and DATEPART(second, %s) = 0 and DATEPART(millisecond, %s) = 0 then FORMAT(%s, 'dd/MM/yyyy') " +
"when DATEPART(second, %s) = 0 and DATEPART(millisecond, %s) = 0 then FORMAT(%s, 'dd/MM/yyyy HH:mm') " +
"when DATEPART(millisecond, %s) > 0 then FORMAT(%s, 'dd/MM/yyyy HH:mm:ss.fff') " +
"else FORMAT(%s, 'dd/MM/yyyy HH:mm:ss') end";
return expression.formatted(
opSql, opSql, opSql, opSql, opSql,
opSql, opSql, opSql,
opSql, opSql,
opSql);
}
},

POSTGRESQL {
@Override
public DbVersion dbVersion() {
return DbVersion.POSTGRESQL;
}

@Override
public String fromDate(final EqlDomainMetadata metadata, final ISingleOperand3 operand) {
// TODO The date/time format should be read from IDates, once this contract is extended to support domain-specific data formats.
// However, there needs to be a database-specific translation between formats.
final var opSql = operand.sql(metadata);
final var expression = "case " +
// TODO DD/MM/YYYY should really only be used for the case of @DateOnly or LocalDate once supported
"when extract(milliseconds from %s \\:\\:timestamp) = 0 and extract(minutes from %s \\:\\:timestamp) = 0 and extract(hours from %s \\:\\:timestamp) = 0 then to_char(%s \\:\\:timestamp , 'DD/MM/YYYY') " +
"when extract(milliseconds from %s \\:\\:timestamp) = 0 then to_char(%s \\:\\:timestamp, 'DD/MM/YYYY HH24:MI') " +
"when cast(floor(extract(milliseconds from %s \\:\\:timestamp)) as integer) - 1000 * cast(floor(extract(seconds from %s \\:\\:timestamp)) as integer) > 0 then to_char(%s \\:\\:timestamp, 'DD/MM/YYYY HH24:MI:SS.MS') " +
"else to_char(%s \\:\\:timestamp, 'DD/MM/YYYY HH24:MI:SS') end";
return expression.formatted(
opSql, opSql, opSql, opSql,
opSql, opSql,
opSql, opSql, opSql,
opSql);
}
},

ORACLE {
@Override
public DbVersion dbVersion() {
return DbVersion.ORACLE;
}

@Override
public String fromDate(final EqlDomainMetadata metadata, final ISingleOperand3 operand) {
return "TO_CHAR(" + operand.sql(metadata) + ", 'YYYY-MM-dd hh24:mm:ss')";
}

@Override
public String fromAny(final EqlDomainMetadata metadata, final ISingleOperand3 operand) {
return DbVersion.ORACLE.castSql(operand.sql(metadata), "VARCHAR2");
}
}
}

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