github.com/dolthub/go-mysql-server@v0.18.0/sql/expression/function/json/json_array.go (about)

     1  // Copyright 2022 Dolthub, Inc.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package json
    16  
    17  import (
    18  	"fmt"
    19  	"strings"
    20  
    21  	"github.com/dolthub/go-mysql-server/sql"
    22  	"github.com/dolthub/go-mysql-server/sql/types"
    23  )
    24  
    25  // JSON_ARRAY([val[, val] ...])
    26  //
    27  // JSONArray Evaluates a (possibly empty) list of values and returns a JSON array containing those values.
    28  //
    29  // https://dev.mysql.com/doc/refman/8.0/en/json-creation-functions.html#function_json-array
    30  
    31  type JSONArray struct {
    32  	vals []sql.Expression
    33  }
    34  
    35  var _ sql.FunctionExpression = (*JSONArray)(nil)
    36  var _ sql.CollationCoercible = (*JSONArray)(nil)
    37  
    38  // NewJSONArray creates a new JSONArray function.
    39  func NewJSONArray(args ...sql.Expression) (sql.Expression, error) {
    40  	return &JSONArray{vals: args}, nil
    41  }
    42  
    43  // FunctionName implements sql.FunctionExpression
    44  func (j JSONArray) FunctionName() string {
    45  	return "json_array"
    46  }
    47  
    48  // Description implements sql.FunctionExpression
    49  func (j JSONArray) Description() string {
    50  	return "creates JSON array."
    51  }
    52  
    53  // IsUnsupported implements sql.UnsupportedFunctionStub
    54  func (j JSONArray) IsUnsupported() bool {
    55  	return false
    56  }
    57  
    58  // Resolved implements the Expression interface.
    59  func (j *JSONArray) Resolved() bool {
    60  	for _, d := range j.vals {
    61  		if !d.Resolved() {
    62  			return false
    63  		}
    64  	}
    65  	return true
    66  }
    67  
    68  // String implements the Expression interface.
    69  func (j *JSONArray) String() string {
    70  	children := j.Children()
    71  	var parts = make([]string, len(children))
    72  
    73  	for i, c := range children {
    74  		parts[i] = c.String()
    75  	}
    76  
    77  	return fmt.Sprintf("%s(%s)", j.FunctionName(), strings.Join(parts, ","))
    78  }
    79  
    80  // Type implements the Expression interface.
    81  func (j *JSONArray) Type() sql.Type {
    82  	return types.JSON
    83  }
    84  
    85  // CollationCoercibility implements the interface sql.CollationCoercible.
    86  func (JSONArray) CollationCoercibility(ctx *sql.Context) (collation sql.CollationID, coercibility byte) {
    87  	return ctx.GetCharacterSet().BinaryCollation(), 2
    88  }
    89  
    90  // IsNullable implements the Expression interface.
    91  func (j *JSONArray) IsNullable() bool {
    92  	for _, d := range j.vals {
    93  		if d.IsNullable() {
    94  			return true
    95  		}
    96  	}
    97  	return false
    98  }
    99  
   100  // Eval implements the Expression interface.
   101  func (j *JSONArray) Eval(ctx *sql.Context, row sql.Row) (interface{}, error) {
   102  	if len(j.vals) == 0 {
   103  		return types.JSONDocument{Val: make([]interface{}, 0)}, nil
   104  	}
   105  
   106  	var resultArray = make([]interface{}, len(j.vals))
   107  
   108  	for i, vs := range j.vals {
   109  		val, err := vs.Eval(ctx, row)
   110  		if err != nil {
   111  			return nil, err
   112  		}
   113  
   114  		switch v := val.(type) {
   115  		case sql.JSONWrapper:
   116  			val = v.ToInterface()
   117  		case []byte:
   118  			val = string(v)
   119  		}
   120  
   121  		resultArray[i] = val
   122  	}
   123  
   124  	return types.JSONDocument{Val: resultArray}, nil
   125  }
   126  
   127  // Children implements the Expression interface.
   128  func (j *JSONArray) Children() []sql.Expression {
   129  	return j.vals
   130  }
   131  
   132  // WithChildren implements the Expression interface.
   133  func (j *JSONArray) WithChildren(children ...sql.Expression) (sql.Expression, error) {
   134  	if len(j.Children()) != len(children) {
   135  		return nil, fmt.Errorf("json_array did not receive the correct amount of args")
   136  	}
   137  
   138  	return NewJSONArray(children...)
   139  }