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

     1  // Copyright 2021 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_OBJECT([key, val[, key, val] ...])
    26  // https://dev.mysql.com/doc/refman/8.0/en/json-creation-functions.html#function_json-object
    27  
    28  // JSONObject Evaluates a (possibly empty) list of key-value pairs and returns a JSON object containing those pairs. An
    29  // error occurs if any key name is NULL or the number of arguments is odd.
    30  type JSONObject struct {
    31  	keyValPairs []sql.Expression
    32  }
    33  
    34  var _ sql.FunctionExpression = JSONObject{}
    35  var _ sql.CollationCoercible = JSONObject{}
    36  
    37  // NewJSONObject creates a new JSONObject function.
    38  func NewJSONObject(exprs ...sql.Expression) (sql.Expression, error) {
    39  	if len(exprs)%2 != 0 {
    40  		return nil, sql.ErrInvalidArgumentNumber.New("JSON_OBJECT", "an even number of", len(exprs))
    41  	}
    42  
    43  	return JSONObject{keyValPairs: exprs}, nil
    44  }
    45  
    46  // FunctionName implements sql.FunctionExpression
    47  func (j JSONObject) FunctionName() string {
    48  	return "json_object"
    49  }
    50  
    51  // Description implements sql.FunctionExpression
    52  func (j JSONObject) Description() string {
    53  	return "creates JSON object."
    54  }
    55  
    56  // IsUnsupported implements sql.UnsupportedFunctionStub
    57  func (j JSONObject) IsUnsupported() bool {
    58  	return false
    59  }
    60  
    61  func (j JSONObject) Resolved() bool {
    62  	for _, child := range j.Children() {
    63  		if child != nil && !child.Resolved() {
    64  			return false
    65  		}
    66  	}
    67  
    68  	return true
    69  }
    70  
    71  func (j JSONObject) String() string {
    72  	children := j.Children()
    73  	var parts = make([]string, len(children))
    74  
    75  	for i, c := range children {
    76  		parts[i] = c.String()
    77  	}
    78  
    79  	return fmt.Sprintf("%s(%s)", j.FunctionName(), strings.Join(parts, ","))
    80  }
    81  
    82  func (j JSONObject) Type() sql.Type {
    83  	return types.JSON
    84  }
    85  
    86  // CollationCoercibility implements the interface sql.CollationCoercible.
    87  func (JSONObject) CollationCoercibility(ctx *sql.Context) (collation sql.CollationID, coercibility byte) {
    88  	return ctx.GetCharacterSet().BinaryCollation(), 2
    89  }
    90  
    91  func (j JSONObject) IsNullable() bool {
    92  	return false
    93  }
    94  
    95  func (j JSONObject) Eval(ctx *sql.Context, row sql.Row) (interface{}, error) {
    96  	obj := make(map[string]interface{}, len(j.keyValPairs)/2)
    97  
    98  	var key string
    99  	for i, expr := range j.keyValPairs {
   100  		val, err := expr.Eval(ctx, row)
   101  		if err != nil {
   102  			return nil, err
   103  		}
   104  		if i%2 == 0 {
   105  			val, _, err := types.LongText.Convert(val)
   106  			if err != nil {
   107  				return nil, err
   108  			}
   109  			key = val.(string)
   110  		} else {
   111  			if json, ok := val.(sql.JSONWrapper); ok {
   112  				val = json.ToInterface()
   113  			}
   114  			obj[key] = val
   115  		}
   116  	}
   117  
   118  	return types.JSONDocument{Val: obj}, nil
   119  }
   120  
   121  func (j JSONObject) Children() []sql.Expression {
   122  	return j.keyValPairs
   123  }
   124  
   125  func (j JSONObject) WithChildren(children ...sql.Expression) (sql.Expression, error) {
   126  	if len(j.Children()) != len(children) {
   127  		return nil, fmt.Errorf("json_object did not receive the correct amount of args")
   128  	}
   129  
   130  	return NewJSONObject(children...)
   131  }